Archive of Our Own ^beta

Chapter Text

Post Core Conception: 3 Years

Gaster sighed as he dragged himself along the high walkways of Hotland, his arms hanging limply by his sides. His skull felt foggy and weighed down with leftover calculations and theories from the day’s work. His feet felt like they were encased in concrete blocks as he moved along towards his home.

It had probably been a week or so since he’d been home, always getting distracted by some new problem at the lab and having little self-restraint when faced with such problems. But after a while his body's lack of rest would catch up to him, making it more of a hindrance than a benefit to have him working there. And he did not want to be a bother to his subordinates, no matter how little he interacted with them.

Gaster’s purple eye lights peered up through the glasses barely staying taped on his head, and wavered for a bit in confusion. There his house was, separated from the rest of the Capital and Hotland to give him the privacy he thrived in. But from the window, a skull was visible, rested on a hand that leant up against the window sill, big eye sockets stared blankly at him. Gaster stopped moving for a moment, feeling guilt creep up on him without really recalling why he should be guilty.

There was something about the way Sans would stare at people when they'd done something that just made them know that someone had seen, and wasn't forgetting anytime soon. Thankfully enough after a moment of meeting Sans’ empty stare, the other skeleton seemed to soften at Gaster’s exhausted state and relent. He left the window, only to reappear at the front door to open it for the scientist who now felt safe enough to at least enter his own house.

There was a long silence as the front door closed. Gaster set down his suitcase and began working his fingers through the fabric of his necktie, trying to pull the knot out. He was so tired, and not looking forward to this conversation. He wouldn't avoid it though, Sans didn't deserve that.

Without turning back to meet Sans’ face however, he spoke his fingers still tugging at the knot around his neck. “So uh...did I miss an Anniversary?”, he tried with a nervous chuckle. He relaxed just a fraction when he heard Sans huff out a laugh in response.

“y’know i don’t care about that stuff dings...”, Sans’ voice wasn't hollow at least. It was tired, but as sad as it made Gaster, that was nothing new. The scientist flinched when a lax hand rested on his shoulder to convince him to turn around. He did so without protest.  Sans’ eye lights were present in the depths of his sockets, but faded.

Gaster hesitantly lifted his head to allow Sans access to his necktie, “What's going on Sans...?” The fabric pulled away frustratingly easily without Gaster’s efforts and Sans pulled the tie over the scientist’s head.

Sans laughed dryly for a second before making his way to the couch and collapsing down into it, “it’s uh...it’s pap.” He stared at Gaster for a moment longer before explaining, “he knows. i don’t know when but he...he saw us making out one time in the house.”

The magic that kept the royal scientist and all that he was together ran cold, “H-he what?” The exhaustion in his bones was soon forgotten and he was pacing back and forth across the living room floor. “But... But we were so careful! Oh shit, ohhhh fuck...”, Gaster let loose a few more explicatives before turning to Sans, “What did you tell him?:

Sans shrugged, “nothing, i had no idea what to do, no idea what to even say...” He looked down at his feet and watched his toes clench, “Dad.”

Gaster froze and turned away, “No, no do not call me that Sans!” His soul shivered in self-disgust. He did not want to hear this.

Sans stood up abruptly, “no i have to, in front of everyone but you when it’s just us! ‘cause despite what we feel for each other, how we should feel according to the entire fucking underground has more precedence in pap’s life!” His voice bordered on hysterics, not really sure who or what he was angry at.

Gaster shrunk more in on himself with every word, not in any state of mind to hear it, not ready to deal with this now or ever really. Sans recoiled as he quickly approached his father to place a hand on his back as purple tears began to fall down his face.

“dings? shit, fuck fuck i’m so...sorry.”, Sans sighed out as he wrapped his arms around the taller skeleton. “i’m sorry i yelled, you didn't deserve that. i’m sorry baby.”, he muttered comforting words into the side of the scientist’s head where his ears might have been had he had them to begin with.

Gaster stifled a sob as he wiped his face, only succeeding in knocking his glasses to the floor while his tears kept falling. “I...I don’t want to l-lose you two! I-I th-thought we'd been careful, I thought-!” He couldn’t stifle the sob again and whimpered as Sans stroked the back of his head and hushed him gently.

“okay okay. i...i know dings, i don’t want you to...shit...to go to jail either.”, Sans said quietly not even wanting to think of that happening. His father was not a sexual predator. It was Sans’ own advancements on his father while they were both hammered drunk that started the relationship, and therefore led to the situation they were in now. They hadn’t even slept together the eight months their relationship had carried on. If his father had to rot away in a dungeon for the rest of his long life, Sans would never be able to forgive himself.

Sans sighed deeply and held on to Gaster’s shoulders tightly, “okay dings, listen for a second okay?” The scientist’s sobs subsided for a moment as his eye lights flickered in lucidity. Sans nodded to him, “this only happened a few hours ago so for right now, in the morning i’ll just tell paps that what he saw is a secret that he can’t tell anyone. i’ll make him promise, he takes those seriously y’know right?”

Gaster opened his mouth to protest but then closed it, “Nn. That should work...for a little while.”

Sans nodded in response, “and...if it doesn’t...” They’d have to stop. Sans didn’t want to say it and Gaster certainly didn’t want to hear it. They understood they were putting their future and the future of their less than ethical relationship, in the hands of a ten year old keeping a secret.

Sans lifted Gaster’s limp head and clicked their teeth together in a lasting kiss, “i love you.”

Gaster nodded looking a little south of hopeless as he let Sans kiss him without reciprocating, now too physically and emotionally drained to do put much effort into anything. “I love you too Sans.”, he whispered in response. Sans leaned back to look at him and wiped away the remaining tears staining his father’s porcelain face.

With a sigh, Sans teleported to the shower upstairs with Gaster in his arms. There was no way he’d be able to care for himself the way he was now.

-

Two months after this scare the two skeletons felt like they could finally breathe again, if even a little bit. Papyrus had apparently kept his secret according to the people around him. When Sans and Gaster would pick him up from school there were no strange looks received from Papyrus’ teachers or classmates, and when Gaster would have to report any findings to the king, he was treated the same as always.

Though they would not push their luck. The only time they would ever kiss or even touch anymore, would be in the privacy of Gaster’s home in Hotland, or his office where there wasn’t a camera.

They still hadn’t slept together, but they had talked some things through just in case it just happened one day, and how they could both make sure not to make one another uncomfortable.

“so you...really don’t like it when i do that? not even a little bit?”, Sans asked with a slight blush on his face, “i kinda thought you secretly liked it...when i called you dad or daddy...”

Gaster’s face however was completely purple and hidden in his hands, “No! I really don’t! It makes me...feel guilty.”

“remind me who got behind who in whose bed and started dry humping them like a dog in heat while they were completely smashed?”, Sans retorted in slight annoyance at this confession.

“Remind me who let it happen! Sans, I liked what you were doing but I should have stopped you!”, Gaster shot back throwing his hands down in frustration.

Sans frowned and took one of the thrown hands in his own and kissed the long delicate fingers gently, “hey...hey dings... it’s okay. remember we’re not playing the blame game here. i just want to know what you want so i don’t hurt you...”

Gaster looked up hesitantly, watching Sans continuously giving his hand kisses along his phalanges. His soul skipped as he glanced away. Sans waited patiently not stopping in his loving attention to the flustered scientist’s hands.

“Mmf...I...your eye...”, Gaster started. Sans listened attentively waiting for him to finish his thought. Gaster’s eye lights refused to meet Sans’ as his free hand covered his mouth in embarrassment. “The magic in your eye lights up...when you’re being possessive... I, uh... I like when you’re like that, like a lot.”

When Gaster met Sans’ gaze again he flinched as only one blazing blue and yellow eye light met his pale two and Sans’ smile was stretched to a devilish smirk, “you’re asking me to be possessive while i fuck you? sweetheart, that’s just me. but if it’ll make you squirm...” A blue tongue emerged from his mouth to glide up one of Gaster’s fingers and into the hole punched straight through his hand. On contact Gaster had to fight to keep quiet as a moan escaped his teeth and he felt more coming right behind it. “i’ll dial it up, just for y o u.”, Sans finished with a deep chuckle that nearly made Gaster whimper.

He was glad there was a table blocking Sans’ view of his lap lest he see the problem he caused, glowing dimly between his clenched legs. Gods, why was this skeleton so good at that?

-

A few weeks later Sans burst through Gaster’s bedroom door, skull flushed blue with his phone clenched in his hand. He went still at the sight he saw before him. Sitting on the bed with his hands in his lap and wearing a very short transparent blue nightgown, a blue ribbon choker, with purple magic visibly glowing from his ribcage and pelvis, was Gaster.

Sans felt his soul flutter and his own magic stir, but found himself speechless as his gaze raked over the form before him again and again.

Gaster’s already purple face, became darker as he gauged Sans’ reaction. “I...I know we already celebrated but, my gift wasn’t uh...done.” He gave a smile pushing through his embarrassment, “Happy 21st, Sans.”

Said skeleton blinked in surprise as he now realized what was going on, he had turned twenty-one last week and...when Gaster said the rest of his gift was coming soon, this was not what he had anticipated.

Sans grinned dumbly as he approached, “y-you...you are...just absolute perfection sweetheart.” As he came closer to Gaster the elder ducked his head to the side shyly.

Sans didn't need to think long to understand the sudden shyness on his father’s part. Yes Sans had seen Gaster naked before, but that had been many years ago, when he could barely use his magic and Papyrus hadn’t even been thought of yet, and the reason why was inarguably innocent and objective as opposed to now.

Gaster hadn’t been under the gaze of anyone he thought that would remember it, and now? He was bearing himself to his lover and just hoping all of his flaws wouldn’t stand out to him. The War had left physical traces all over him. His bones weren’t the pristine white they’d been in his adolescent years, and there were countless chips and scrapes along them, too old to ever heal properly. Gaster limited his wardrobe to long sleeves and long pants for a reason, this was the most anyone had seen of him in this way, ever.

Sans’ hands came to cup Gaster’s face and bring it to face him, Gaster’s eye lights however, hesitated to follow. Sans nuzzled Gaster’s face with his own mumbling to him lowly, “y’know you look gorgeous don’tcha? you know you always look gorgeous don’tcha?” Gaster gave a noncommittal sound out of his closed mouth in response, his eye lights glued to the floor his face burning in embarrassment. Sans gave a soft chuckle his mouth clicking against Gaster’s cheek and the side of his mouth, “i know you probably don’t believe me, not much i can do to change that.”

Gaster then jolted in surprise when one of Sans’ hands left his face to rest on his spine through the thin fabric of his nightgown and squeezed. “doesn’t mean i won’t try.”, Sans stated lowly. Gaster’s mouth opened in a gasp from the shock of pleasure and Sans, taking full advantage, shoved his tongue inside Gaster’s mouth. The scientist’s hand left his lap to hold Sans’ shoulders as he allowed the sudden kiss and went along with it. Their teeth clicked together at every turn of their heads their tongues swirling around, tasting each other, exploring each other's mouth.

Gaster moaned softly as Sans’ hands moved down to rest on his hips, feeling the bones through blue fabric. He could feel one of the hands start to push the transparent fabric upwards, exposing more of his bones to the cold air of the room. Gaster barely kept back a whine when Sans pulled away from their open mouthed kiss. “Haaa...S-Sans.”, he breathed wondering why he’d ended it so abruptly.

Sans shushed him as he leaned back but didn’t remove his hands from his hips, “Ah fuck...you’re too good to me babe. Are you sure about this though?” Gaster blinked absently for a moment, taking Sans’ serious expression and change in tone into mind. He was giving him an out. Gaster had initiated this and Sans was giving him an out. Gaster smiled a little, how sweet, he thought.

But no, he wanted to do this, he wanted to make Sans feel good, he wanted Sans to fuck him, make love to him and everything in between.

Gaster moved forward a little further to wrap his arms around Sans’ neck and used his lilac tongue to trace a trail from his shoulder blade to his collarbone, Sans shuddered in response. He then murmured into his neck, “Please fuck me Sans.”

Not even a second later and Gaster was pushed back onto the bed, bouncing with the mattress. Sans was on him in seconds, poised more like an animal over its prey than anything else. Now that he was close enough, Sans could smell Gaster. Not just his natural scent, but the scent of his magic barely concealed behind the blue fabric of the nightgown he wore. Unformed but begging for direct stimulation with how fast it was shifting around in Gaster’s pelvis.

Sans groaned and leaned down to bite into Gaster’s neck under the choker. He cried out in surprise and arousal, his spine arcing and pushing his hips towards Sans’. But Sans’ hands held the taller but thinner monster’s bones down with ease. “you look so pretty all dressed up for me, where’d you get the clothes babe?”, Sans murmured into Gaster’s neck as his loving bites went into his collarbone.

Gaster let out a shaky breath as he felt Sans speaking, hot magic spilling out of his mouth in a fog, over Gaster’s bones and then into the air. “M-m-made them. Fabric from theEAH!”, his voice shot up in volume as Sans now dipped his tongue into the collar of the nightgown to reach the sternum hidden beneath. His tongue ran over patches of smooth and coarse bones, giving the entire area his loving attention.

Sans gave a chuckle as he paused, giving Gaster a glance from his position, head nestled into his shoulder. “come on, finish your report dings, before i get too impatient and have to ruin all your hard work.”, the sharp canines usually hidden behind his huge teeth peered out of hiding for a moment.

Gaster whined as a shiver coursed through him, shifting as Sans continued his attentions to parts of his body that weren’t used to being touched, usually covered by some form of heavy clothing. “Haaa...the-the fabric from t-the du-AH! The dump! U-used a colleague’s s-sewing machine! Nnaah! Sans!”, the entire time he tried to speak to Sans, said skeleton’s attentions had spread out across his body.

His wayward hands had been taken delicately in one of Sans’ while his other worked it’s way over Gaster’s now exposed pelvis, paying special attention to the hip bones while avoiding the purple magic floating tense in wait. Meanwhile the bites had been focused on the collar of his nightgown that he'd spent hours on, the first bite only gripping the fabric loosely, only implying Sans’ intentions if Gaster didn't hurry.

“W-wait hhh, I don't k-know what else you w-w-want me to say! Hn!”, Gaster whined as he felt the bites to his gown become more aggressive and hungry.

Sans paused for a moment, and chuckled lightly. “how’d you prepare yourself? your delicious pussy is practically formed already, did you play with yourself? or perhaps...”, a bite strong enough to nearly draw marrow was given to his collarbone making Gaster whimper, “did you watch someone else? did you watch someone fucking their bitch and imagine they were fucking you...? get yourself all nice and horny before i came over?” His voice was deepened to a growl that poorly hid it's possessive tone.

The bites to his bones and gown resumed tenfold and the hold on Gaster’s hip became fierce. He cried out a moan, “N-no I didn’t! I-I would never w-want to be f-fucked by a-AHA! Anyone but you! Sans!” He moaned out everything he knew Sans wanted to hear and more, “I'm yours Sans, yours! I-ah! I played w-with my soul thinking of you! Only you! I-I wanted you to be here, touching me, kissing me, f-fucking me! I wanted to be your bitch, not anyone else’s!

Sans chuckled darkly and finally pulled away from Gaster’s neck and shoulder area, lovingly looking over the damage he’d left behind. He then looked at Gaster’s face, tears of pleasure had started to gather in the corners of his eye sockets, Sans leaned down to lick them away making Gaster look at him once more. Their eye lights connected for a long moment before Sans laughed, “sorry i’ll have to disappoint then babe. you’re not my bitch, as beautiful as you are? i'm lucky to be able to fuck perfection like you...”, as he spoke his hand that had been holding Gaster’s hip moved.  His fingers pinched the hem of the nightgown to move it to the base of Gaster’s ribcage for easier access, then he gripped the now visible spine.

With quick but gentle movements Sans started spine-jerking Gaster and watched his body react wondrously. The hands still held by the monster on top of him struggled to find purchase as the waves of pleasure rolled in on him. His legs were more successful in this, being able to grip and pull at the sheets under him. The rest of his body arced away and towards the attention all at once, the only force keeping him from bucking clean into the air, being the hand moving along his spine.

Gaster tried his hardest not to let his voice get too loud, but oh fuck he’d never felt something like this all at once. “Ah, ah! HAHHH!”, a whine broke out of his mouth soon after. Too good, it was too good. And Sans was staring at his face too attentively, Gaster could feel his soul beating away in embarrassment as he couldn’t bring his gaze to meet Sans’ directly. “S-Sans! ST-stop st-aring!”, he attempted through the pleasure to stop the source of his embarrassment.

“can’t do that sweetheart, sorry, you’re so...fucking gorgeous i can’t.”, Sans replied enraptured by the sight below him. Gaster whined weakly in protest, unhappy, but not seeing any way to stop him. Sans smiled deciding to have a little pity on the elder monster, “alright alright, only because looking at you for this next bit would be painful.”

Gaster huffed out a whine of confusion but stopped as Sans stopped jerking his spine, “Sans?” He felt his hands being moved from over his head to his lower spine, but were still held securely in Sans’. The other hand of his lover again held his hip with a little bit of pressure, hot magic was breathed on his still unformed magic. Oh. “S-Sans?”, he uttered now realizing what was happening but still wanting to get some reassurance.

“uh huh? what’s up dings?”, Sans answered with a tone that allowed some kindness in it as he stopped moving. Another out.

Gaster shifted a bit with a whine, “I uh...I'm already c-close.” He wouldn’t take it, he wanted this, now more than ever. Sans laughed against his magic, making him and the particles of arousal shiver.

“then this’ll be perfect. i’ll make you cum in my mouth, then you’ll cum on my cock, then i’ll cum in you.”, Sans stated calmly before leaning forward tongue already sticking out.

Gaster didn’t get much time to sputter at Sans’ lewdness before his fog magic was breached by Sans’ tongue, it sparked and formed into a more than eager entrance sitting in Gaster’s pelvis. “HN-! S-Sans!”, Gaster near shrieked his hips jolting. Sans didn’t wait to chase it, wanting to hear more noises like that as soon as possible, he immediately licked a long stripe up to Gaster’s clit. The hold on Gaster’s hip kept him from bucking down onto Sans’ tongue, but his moans spoke for him. “HaaaH! Ggh! Sans! S-snnn! Sa-ANS! M-morre! Please, pl-hhhease! More!”

Sans wasn’t about to ignore such an enticing request, and so put his tongue to work. With every pass made on Gaster’s clit, the scientist near screamed and the force of his bucks would triple all at once. He was moaning, whimpering, and Sans wished he could see the expression he was making when his tongue pushed inside the magic cavity.

He could feel how close Gaster was throughout his whole body, his hands were cramping up from clenching at nothing, his hips were trembling, his legs that had automatically clamped around Sans’ head the moment he began tongue-fucking his father were tightening their grip sporadically, the pussy his tongue was buried in and eating out of was desperately pulling him deeper inside with walls fluttering. “GGH! NNnh! HaH!”, Gaster’s moans were slowly becoming drunken in pleasure. Sans diligently sucked and licked the inside of his father’s pussy, chasing what he knew was right there. Gaster shrieked unrestrained, “NNAH S-Sa-SANS! SANS!” He squirted hard into Sans’ mouth which worked him through his climax, lapping up and drinking the liquids that seemingly endlessly leaked out of the trembling hole.

When Gaster found his body going lax after a while, Sans was able to free himself from the tangle of his father’s long legs to look at Gaster’s face.

“oh fuck...”, Sans breathed out at the stunning sight.

Gaster’s face had traces of more tears from the pleasure, his mouth still parted to breathe shallow breaths that pushed out hot magic in their wake, his bones were glowing softly and his expression was one of complete ecstasy with eye sockets half-lidded and eye lights slightly staticy. “Hhhaaaa...”, the soft whine came out in between his breaths.

Sans swallowed, his nonexistent throat going dry, “uh d-dings? y-you still with me?” He moved a hand to wipe Gaster’s face clean once again.

Gaster’s eye lights sluggishly responded, flickering as they roamed the depths of his sockets, but finally solidifying as they found Sans. “Hnn... S-Sans.”, he muttered as his lucidity returned, “Was so good...too good. Sans...”

Sans chuckled as he brought himself up to Gaster’s face again letting go of his hands, “glad to hear. could say the same about this pussy of yours, tastes so fucking good. in fact, here. have a sampler.” With that he kissed Gaster again, the other skeleton responding by placing his free hands on the back of Sans’ head as he let Sans take control.

Soft moans were heard in between the lewd noises their tongues made as they slid along each other, saliva, and Gaster’s own cum being mixed throughout. Though it only took a bit for Gaster to realize that soon he was the only one moaning anymore, after Sans had started grunting softly his hips keeping incredibly still above him. The glow of blue magic was blatantly obvious through Sans’ shorts and Gaster felt himself smirking, did he think he didn’t notice?

Gaster moved one of his hands to reach under Sans’ shorts where his magic hid, and was amused when it reacted immediately with a louder grunt from above him, forming into a cock he could already feel was semi-hard. Before he could do anything, Sans had his hand over his own and he broke the kiss.

Their eye lights flashed as they met one another. “you don’t have to do that. we can stop if you’re tired.”, Sans offered yet another out. And this time Gaster found himself getting a little irritated.

“You don’t have to keep giving me chances to not continue. I said from the beginning that I want this Sans, I want you to fuck me.”, he assured without any embarrassment or hesitation. He loved that Sans was making sure and he understood, but he wanted to be heard and listened to.

Sans nodded hesitantly, “y-yeah i know but-” Gaster didn’t let him finish.

He decided he would...reiterate his needs. “I want you inside me. Want your cock in me, inside my pussy. Fucking me, making love to me! Filling me up with your cum! Please fuck me Sans?”, he shamelessly begged Sans to fuck him until the flustered monster let go of his hand still gripping his cock with a groan.

Gaster smirked satisfied with himself as he moved his hand along the length peeking out of the waistband of Sans’ shorts, now fully hard. His pussy throbbed in need the more attentively he observed it but then a soft groan caught his attention and he looked up. Shit.

Sans’ skull was illuminated sharply by the blue magic flaring in his left eye, staring straight into Gaster as his hips bucked into his hand. Not making anything of his sins crawl on his back, but rather, he could feel Sans’ own sinful thoughts being sent straight through his soul. He knew indulging in his lover’s possessive nature was very likely massively unhealthy, but there was a large part of him that didn’t care. That liked the thought of someone caring for him so strongly that they’d do anything for them, and do anything to make sure they'd keep him to their self. He squirmed trying to keep back a moan.

Sans pulled away from Gaster’s hand to catch his breath and restrain himself so he wouldn’t cum too early, Gaster could do multiple rounds apparently, Sans however was less confident in his stamina. Sans’ next groan bordered on a growl, one of his hands going to Gaster’s still sensitive pussy. “you're so fucking hot babe, begging for my cock like that, you want it inside that bad?”, he groaned as he played with his father’s clit making him squirm even harder.

“Mmm! Yes, yes S-Ssans!”, Gaster moaned. Sans groaned as he gathered up the liquids still leaking out of Gaster’s pussy and spread it along his dick, stroking himself with it. Gaster was already soaked inside, but Sans wasn’t about to take any chances with his father’s comfort.

Sans pushed his member up against Gaster’s pussy and leaned down to the side of his head, “you’re so fucking gorgeous dings...” And like that he began pushing inside, Gaster yelped and his hands shot up to hold on to Sans’ jacket. Sans shushed him and used the hand not holding him up to stroke Gaster’s spine calmingly. Gaster’s cum still in his cunt had been enough for Sans to push inside, but this was his first time like this, and Sans did not want to hurt him. As Gaster’s breathing calmed and he was able to relax, the rest of Sans’ cock was pushed inside his tight cunt.

“Hnnm... Oh fuck, S-Sans!”, he breathed out as he held fast to Sans’ jacket that was barely hanging on his shoulders. Sans nuzzled Gaster’s collarbone lovingly as he forced himself to stay still for both their sakes, not wanting to hurt Gaster and not wanting to cum so soon.

He recalled their conversation a few weeks ago to distract himself, while Gaster definitely did not like when Sans called him dad in any setting. Sans...Sans did.

He had the biggest daddy kink and it was killing him not to be indulging in it in the most pressing situation. Actually fucking, his actual father. But his need for Gaster to be comfortable was taking precedence. If things had been different, he’d be calling Gaster dad, daddy, father and nothing else. He’d be groaning into the scientist’s mouth how they were so dirty, a son fucking his father, kissing him, filling him to the brim with his cum.

At this moment all he wanted to say was, ‘how does my cock feel daddy? too big? hitting all your insides perfectly? your pussy feels so tight and hot daddy, i'll make sure to fuck you properly ok?’

But he stayed quiet, gods he made himself stay quiet. The minutes of waiting were brought to a stop by Gaster moaning as he rolled his hips down on Sans’ cock, “S-Sans...Sans please. Move, you can move now!”

Sans complied, more than willing to move for his father, his hips moving slowly but powerfully to start. Gaster’s soft pants and groans, paired with the clenching of his pussy around Sans were amazing to experience, but he needed to feel more.

Gaster’s legs wrapped around his back as Sans began thrusting his hips faster, his moans becoming instantly louder. His hands were scrambling for purchase on Sans’ jacket but they kept slipping so instead he gripped at his back, trying to ground himself through the overwhelming pleasure. “F-fu-FUA-FUCK SA-AANS!”, he cried as Sans’ thrusts increased in speed and strength once again. Gaster didn’t even think that was possible five seconds before. His eye sockets were filling with tears of overstimulation as his body rocked with the force of Sans’ hips against his, his dick inside Gaster’s now spasming cunt.

“you're soooo-fucking good! fucking amazing amazing, a-amazing... so cute, ad-adorable and mine...mine m-mmhhh...mine all mine! shit gaster!”, Sans babbled as his thrusts started to lose rhythm and became erratic. Gaster meanwhile seemed to lose all form of speech as he screamed and moaned into Sans’ jacket, completely drowned in the pleasure.

Sans groaned more into Gaster’s neck as he felt his body tensing up, “oh fuck, y-you gonna cum dings? i can feel your pussy-oh fuck! ti-iiiight! tightening around me! shit! shit shit, cum for me! c-cum on my cock, cum on my cock daddy!” Sans growled as Gaster’s cunt clenched around him and he felt cum soak his dick and some leak out onto the mattress. Neither seemed to notice Sans’ freudian slip as Gaster melted into the bed waiting for Sans to finish and still coming down from his climax.

Sans felt his hips stuttering in movement seconds later and wordlessly moaned into the pillow under Gaster’s head as he filled him up. Gaster whined absently at the sensation, more cum spilling out in between his cunt and Sans’s cock and gathering on the mattress below them.

Sans groaned weakly as he reluctantly pulled himself out of Gaster to observe his work, fuck Gaster was overflowing, that’d be a mess later. He leaned down to gather the overflow on his tongue, to which Gaster jolted and moaned. Sans then pulled the mixture of cum into his mouth, before leaning over Gaster’s face. He clicked their teeth together and Gaster opened his mouth, their tongues swirled together, tasting each others cum in their mouths.

Sans rolled to his left to collapse next to Gaster, finally feeling himself come down from his high.

Gaster found himself able to move before Sans was and adjusted the shorter skeleton to be the little spoon as he held him in the now messy bed. “Did you like your present?”

Sans nodded contentedly as he allowed himself to be spooned, the other monster was taller so it made sense. “mmph... mm hmm. you were so good for me dings... it was the best.”, he responded lying his hand on Gaster’s that rested on his hip.

Gaster smiled softly, “I'm glad.” He gave himself a critical once over, “My gown is ruined.”

Sans chuckled tiredly, “dings, if you want more, hell, i'll make ‘em for you. you can wear the next one on giftmas.”

“What? No, no you don’t need to...”, Gaster began.

“i want to. sorry to say i didn’t spend much time committing to memory, was uh, heh, distracted.”, Sans admitted with a smirk. Gaster didn’t see any way to dispute  that and so, dropped the matter. If Sans wanted to do something, he couldn’t very well stop him.

He smiled softly, “I love you.”

“i love you too dings.”

Chapter Text

Post Core Conception: 1 Year

Gaster’s tired eye lights glowed dimly, following command after command as they scrolled across his computer screen. Letters, numbers and other assortments of characters had long since merged together to read as nothing more but incoherent blobs before him.

One of his hands held up his head, while the other numbly squeezed a stress ball with a frustratingly jovial face drawn on it, a last ditch effort to keep himself awake that was not working in the slightest. In fact Gaster was convinced the mind-numbing repeated squeezing, was making him more tired than anything.

Coming to this realization promptly woke Gaster up for a moment. His irritation spiked and he threw the stress ball straight at the computer screen. “Goddamn it.”, he muttered to himself as he watched the ball bounce back and come to a stop next to his elbow.

He stared at it for a good few seconds before swatting it to the floor, very much like a scorned cat, out of spite for the inanimate object.

That didn't help him feel better... Maybe if he punched the computer...no that'd hurt. But pain would surely wake him up at least? Gaster juggled the options up and down in his mind for a bit, and before his rationality could hold his hand, he punched straight through the computer monitor.

The pain hit him like cold water in the face. Regret. Mistake. Stupid! All of the rage in his soul looking at his own rashness came out at once, “FUCK A-! FUCK!” Well he was certainly awake now.

“dad?”, a deep voice from behind caused Gaster to drop his face into his free hand.

He felt embarrassment creep up on him, but had no time to wallow in it before his son came to his side to survey the damage Gaster had done to himself. He flinched sharply as Sans gently took the arm stuck in the monitor and began to pull, “Hello Sans. What are you-ow OW-doing here?”

Sans gave a bemused chuckle tugging a bit harder on his dad's arm, “checking up on you, just finished my shift, we’re the only ones left... now, i’ve heard of punching in numbers, but i don't think that's synonymous with punching your computer?”

Gaster grit his teeth as he felt sharp plastic digging into his bones and scraping him as Sans was able to separate the computer and his hand from each other. The trashed monitor crashed to the floor in front of the cluttered desk Gaster had been using. His eye lights rolled in his sockets at Sans’ jokes, before bringing his arm up to observe the damage for himself. Not too bad actually, easily treatable. Felt a lot worse than it looked at least.

“Ha bloody ha, very clever. But I, don't need to punch in numbers for any calculation. My mental math is flawless.”, Gaster stated only half-joking in a prideful manner. He then stood from his chair with a simple nod in thanks to Sans.

His son snorted at this, but it didn’t take long for his eye sockets to narrow slightly in worry. He stuffed his hands into his jacket pockets with a sigh, “dad, you shouldn't be stressing this much over something, that yes could be improved, but at it's most core function, works.”

Gaster sighed as he was tailed on his way over to the emergency wash station, pulling his ruined lab coat sleeve up to his elbow. “ ‘Works’ is a relative term. It functions poorly and half the underground get shorts in electricity that last for days at a time.”, he turned the water on and shoved his bare arm under the water flow. He avoided Sans’ stare as he came up next to him, and lifted his other hand to hover over his wound, a purple glow emanated from his fingers and travelled into the water running over his arm.

Neither of the skeleton monsters said a word as they watched the scrapes and gashes that leaked marrow, slowly become nothing more than a dull ache only Gaster could feel, where the wounds used to be. Gaster sighed as he let his magic flow fade away and still feeling his son’s concerned gaze on him, tried to calm his nerves.

“I apologize Sans. I know I'm worrying you, sometimes I can't help but look at a problem and... want to solve it as soon as I can. I don't take care with my health, and I should.”, he apologized without making eye contact with his son, pat-drying his arm dry.

Sans didn't say anything for a moment and then shook his head, “nah, i do the same thing sometimes. i get it...worried pap whenever i overdo it, so i get how you feel now too.” His son gave a tired chuckle before holding out a roll of bandages for Gaster, god only knew where he got it, but the doctor wasn't complaining.

Gaster thanked him as he accepted the roll of bandages and pulled out the edge with his teeth. “Now that’s curious. What has you working overtime?”

Sans shrugged giving a noncommittal hum, “just a theoretical project, nothing too involved. i'm staying up doing calculations mostly, figuring out some stuff.” His eye lights watched Gaster out the corner of his eye socket as the scientist wrapped his injured arm, “it doesn't have much to do with the core really so no worries, i don't work on it here.”

Gaster glanced down at him interest sparking in his eye lights, “What does it have to do with the core?”

Sans blinked and looked up at his father's face, intrigued but professional, and in a way...so open. Sans shook his head giving a confused grin, “uh... it doesn't have-.”

“You said it doesn't have ‘much’ to do with the core.”, Gaster pointed out before turning his attention back to his task, “Which implies it does have something to do with the core. Go ahead, tell me, it might give me a spark of inspiration.”

His son gave an embarrassed grin looking off to the side, and Gaster could tell that Sans wasn’t sure about talking. It stung for a moment to realize that Sans wouldn’t put confidence in him concerning his work, but he shrugged it off as he secured the bandages around his arm and let his arm drop to his side. “Alright I won’t push it, if you’re this secretive about it, it must be something good.”, Gaster said with a smile.

Sans looked up to him shaking his head, “nah that’s not it. there’s really clever things, then there’s super stupid things. don’t wanna waste your time.”

Gaster gave a frown as he looked down at Sans, multiple different times he’d heard his peers at the lab and Sans speaking in passing, and when his son wasn’t joking around, they spoke about their work. Sans worked in the lab assisting with the core with his theoretic work in a different wing from where Gaster was stationed, nearer to the Core. But often Gaster would have to convene with the staff of that wing, to collaborate on how to improve and stabilize the powerhouse of the Underground.

Whenever Sans’ own theories or ideas would come up in conversation, they were often shot down or demeaned, but by no one but Sans himself. Which Gaster would have understood the his input been unhelpful, but it was just the opposite. Sans had so much potential but he rarely ever believed in himself, and Gaster was tired of trying to reassure Sans and not being taken seriously. Everytime he would praise his son’s intellect he’d be brushed off with a grin or a laugh. And he figured it was high time that he figured out a different approach to getting through to Sans.

With that thought in mind, Gaster pulled off his ruined lab coat and threw it down on the floor, Sans flinched and grinned uncomfortably. “uh, are you gonna punch something again?”, he trailed off as he noticed his father smiling, “dad?”

Gaster’s smile just widened, “Let’s go.” He walked past Sans ushering him towards the exit by the shoulder, disregarding his confused protests. “And call a sitter for Paps.”, he grabbed his trench coat off the hook by the lab door.

Sans just looked up at him puzzled but not protesting anymore, “where are we even going?”

“We’re getting drunk.”

“...seriously?”

-

Any other protests in Sans’ mind were gone from the moment he knocked back his first shot of whiskey. Alcohol after a long day of work sounded like a nice way to wind down, and his father was buying so why not? He thought it a little strange that he’d been dragged to a bar only after he’d opted out of talking about his at home project, but he appreciated the time away from work. Even when he was home, he worked and took care of Papyrus, so this was an appreciated respite.

Though he was wondering something as he looked to his father sitting in the booth next to him, how well could his father hold his liquor? He’d seen his father drunk maybe twice in his nineteen years, but he’d never seen him while actually drinking before. He still seemed sober after two shots, but Sans couldn’t really tell. His father’s neutral expression spanned across many of his emotions and states of being, drunkenness could also have been one of them. Gaster looked at him, “Something wrong?”

Sans then realized he was staring and shook his head looking back at his empty shot glass, contemplating it before holding it out again. Gaster poured him another shot from the bottle he’d ordered, “Sans. Why don’t you think your theoretic work isn’t brilliant?”

Sans glanced up at his father before smirking and knocking back his shot glass once more, the magic in his soul stung and buzzed for a moment before subsiding. He chuckled, “and the true reason for our spontaneous trip, emerges! could’a waited till i was a little more drunk y’know.”

Gaster scoffed pouring them each another glass, “You would’ve noticed no matter how drunk you got Sans. I won’t insult your intelligence.” He knocked back his drink and concentrated on the buzzing sensation it gave his soul and senses, he stared at the table in front of them. “I’m worried about you. Can’t you talk to me?”, he asked delicately.

Sans huffed out a laugh giving his father a pat on his shoulder as he finished off his own shot, “i appreciate the concern dad, really i do it’s just...” He placed his glass down a bit loudly, motioning for another drink. Gaster was unsure already having noted slowed movement and slurring speech in his son’s behavior, but poured once more now that they were actually talking. Sans looked miserable as he finished off the drink seconds after Gaster finished pouring it, “i just...i trust ya’ dad but i can’t... there ain’t no way i could ever be as ‘brilliant’ as you.”

Gaster blinked taken aback by this statement, never had he thought that, he himself were the reason for his son’s lack in self-confidence. That made this more difficult of a situation, but at least Sans had opened up a little bit. But even he was surprised when Sans continued to speak to him.

“i mean, everything ya’ do is huge, and awesome! i dunno if i could ever even...you astound me dings and i...pfft! can’t believe i never asked but we’re getting drunk and, well what better time right?”, Sans glanced up as his father as his head rested in his crossed arms on the table, “why are you in science anyway? did gramps convince ya’ to or...” Sans trailed off in his question as he watched Gaster’s expression darken, he glanced at the bottle now sitting in between them at the table. They were here to talk about him, Sans understood that but...he was ashamed to admit that he’d never asked much about any family Gaster had before him and Papyrus. Gaster had always been enough, he still was. But Sans just didn’t understand why Gaster did what he did, and how he could still be doing it so passionately after years and years of it. Something had to be the cause, no one just had drive like the Royal Scientist did.

So Sans reached for the bottle before being stopped by Gaster who gave him a look, Sans grinned. “it’s not for me dad.” The statement was enough to convince Gaster to remove his hand, allowing Sans to pour him a drink. He knew what was happening, but he didn’t mind. He was doing the same thing to his son, might as well be fair and open up about himself as well.

He lifted his shot glass, “When I was around five or six, I lived in a small village of monsterkind. With my mother, my father, and my older sister.” He didn’t look to see Sans’ expression as he explained, and rather paid attention to his drink as he downed it. He felt the burn and honed on it, imagining it was stronger to distract his mind from delving into emotions, and focus on sharing his story. “My mother left the village on a supply run one day with a group of other monsters, and none of them were ever seen again. My mother, was a loving woman, dedicated but headstrong. So we knew long before they found her dust months later, that she had been killed... My father was all we had left, and Sans?”, Gaster finally looked to his son’s face taking in his somber expression. “He was awesome.”, Gaster admitted finally allowing himself to feel something at a somewhat happy memory he had from his childhood.

Gaster went on for an hour, sharing how being raised by his father and sister, both having been more aggressive souls than him, pushed him to use his mind more than his strength. And while his family did not frown upon his adequacy in brains over brawn, they were not similarly skilled, so they got Gaster all the books they could find. Concerning mythology, astrology, and eventually engineering and chemistry. He took all of it in stride, and eventually Gaster admitted with a sad smile, “Science was all I ever had Sans. I was one of three children in our entire village, including my sister, and even back then I was...socially...just bad... I didn’t make friends easily y’know?”

It was at that point that Gaster realized that both he and Sans had downed the bottle down to a fourth of whiskey without Gaster stopping them, he sighed. Whatever, but there was a hell of a hangover in their near future. What time was it?

Gaster shook his head feeling like there was a heavy fog that wouldn’t dissipate inside his skull, “So I, stick with science, ‘cause that’s all I am. Wingding Gaster, The Science Master!” The joke title he’d received back when he’d first begun working in the King’s scientific staff left nothing but a bitter taste in his mouth and he rested his head on the table.

“So that’s me, sticking with one thing, too scared to move off stable ground and plummet. But I’ve reached the peak of my capabilities and now I’m stuck, and...there’s nothing left but breaking the barrier...”, Gaster’s voice softened as he began muttering losing his train of thought as his eye sockets burned, “We’re trapped underground with shit supplies, monsters falling down left and right, birth rates already climbing, and I finally figure out a way for us to not have to rely on fucking glow worms, candles, torches and rechargeable batteries for light and all everyone wants is the barrier gone! The barrier the barrier! ‘Haven’t ya’ figured out the barrier yet?’ ‘When are ya’ gonna focus on the barrier?’ ‘Shouldn’t ya’ be working on the goddamn barrier?’ Well gee whiz ya’ know what, I’ll get right on that Jerry-OH WAIT! I can’t fucking see my miracle solution button ‘cause it’s TOO. DARK!” With that he slammed his open palms on the table, drawing the attention of the barkeep that gave the skeletons an annoyed look, before recognizing Gaster and decided to let the slight disruption slide for the Royal Scientist.

The silence after Gaster had finished his tangent was tense, Sans just stared in shock at his father, wondering how he’d never seen evidence of all the stress he’d been under all this time. He placed a careful hand on Gaster’s shaking back, feeling guilt press down on his soul. He pretended not to notice the tears he saw falling and instead turned his attention to the nearly empty bottle of alcohol in front of them. “i uh...i guess i didn’t think about that... bein’ at the top is, a lotta pressure on ya’. ‘m sorry.”

Gaster let out a soft laugh, before shaking his head. He wiped at his eye sockets and gave Sans a tired smile, “It felt nice to tell ya’. We rarely talk, we should go drinking more of’en.” Sans truly smiled at that, liking the idea. With how Gaster was looking at him, so trustingly, so openly... He looked so cute, of course Sans would-... Wait what?

Sans paused for a moment as he thought over what he’d just thought, cute? I mean, yeah, his dad had always been adorable to him in ways a father shouldn't be to his son. It wasn’t right and Sans knew that, but he couldn’t help but think it every time he saw him! But no, Sans had to stop thinking about it as soon as possible, what if he said something he wouldn’t be able to take back? Fuck, this was getting dicey.

Sans made to stand and suggest that they leave before he saw Gaster do the unthinkable as he poured Sans another shot, emptying the bottle with a clearly drunk and warm smile, as he ordered another bottle for the table.

Sans let out a nervous laugh, “uh dad? are you sure we-?” Gaster wouldn't hear it.

“Uh uh, I!”, Gaster motioned to himself and thanked the barkeep as they delivered the fresh bottle to the table before continuing, “Just spilled my metaphorical guts Sans. Til’ you speak, we ain't leaving. Don't care how drunk we need to get alrigh’?”

Sans rubbed the back of his skull and opened his mouth to speak before he was yanked down by his arm to sit back down in the booth. He would have yelled had a drink not been shoved into his face and Gaster not leant down right behind it, staticy eye lights glowing lilac as they met Sans’. This was innocent on his father’s part, it was innocent, completely normal. He was being a concerned parent, this was not meant to be seductive, not hot at all. Not hot? Oh it was hot, but Sans couldn’t see it that way, not here, not in front of Gaster. Fuck he had to get out of-“Drink.”, Gaster ordered with a kind smile.

Sans found himself obeying in seconds, downing his drink in record time before he could think of teleporting away. Fuck he was weak. Gaster nodded in assent, satisfied with himself as he continued pouring them more drinks through the next hour. Sans felt bolted in place until he was too inebriated to remember why he was so anxious, and relaxed.

After Sans had finally relented, too drunk to hold back anymore, the Royal Scientist had allowed them to stop their binge and go home. Which was what preceded Sans now having his arms wrapped around Gaster’s shoulders as his father piggybacked him to the scientist's home. It took over twenty-five minutes for the drunken skeletons to reach their destination that was only ten minutes away from the bar they drank at. Sans was half-unconscious, mumbling into the back of Gaster’s head and neck.

Gaster paid it no mind, though his drunken mind found it funny and wanted to know who Sans thought Gaster was. It was halfway into their second bottle that Sans had started looking and talking to Gaster as if he were his lover, complimenting him, fawning over him. In fact the only reason he was carrying Sans like this - besides not trusting his son’s balance - was so his hands wouldn’t start to wander anywhere uncomfortable again.

When he had tried carrying Sans bridal style, he felt fingers pushing at his ribs and spine through the fabric of his sweater, and the fireman carry was no better as he felt his hip bones being touched and the band of his pants nearly being breached. Even now with Sans half-asleep and fully drunk, there were brushes along his collarbones, and pressure being put on his sternum.

Gaster shook his head as they finally reached home, dismissing his discomfort, and looked forward to the moment he could plop Sans on the guest bed and head to bed himself. He wouldn’t bring this up the next day, it’d be much too awkward. He’d be kind, and pretend that nothing had happened at all, and Sans would never remember anyways so, why bother?

In the back of his mind Gaster thought over what Sans had admitted to him in his drunken state.

“i mean, it's harrrd. er’body looks at me like i shoul’ be sum sorta progidy or sum shit ‘cause ur my dad. annnn? i’m not! surprise evr’yone! i’m a piece o’ trash that can’t think good lik my dad! a-a-an i jus’...”, he remembered Sans’ eye sockets welling with blue tears and his soul burned just remembering it, “i jus’ feel like i let evr’yone down dad, so it's better ta’ let ya’ take charge. so no one’ll pay attention to me an’ jus’ be let down...”

Gaster opened the front door to his home and walked in before leaning back against it to shut it closed. He sighed, “We're home now Sans...”

His son only mumbled in reply only a few words coming out English, “Hnm...Gast...daddy...” Gaster gave a tired smile, it'd been years since he heard Sans call him that. Papyrus still did, but in a few years, “daddy” would become “dad”. And he was alright with that, but hopefully Papyrus wouldn’t also call him “Dings” like his oldest sometimes did as a joke, though he doubted that would happen.

He made his way over to the base of the stairs that let to the second floor bedrooms and considered them for a moment, then he grabbed the banister and pulled his way up to the second floor.

Gaster had to quite literally pry Sans off of him once he’d laid him down, he was like a clingy sloth, refusing to release his neck even in the grasps of sleep. It surprised the man to realize how strong Sans could be if he really didn’t want to let go of something. Once he was free, Gaster tucked Sans in under the light blankets of the bed and left to go to his own room.

He didn't take much time to throw his shoes to the floor and collapse face first into the comfort of his bed, not needing the layer of warmth his covers would provide to start to doze off.

His mind began to wander as darkness enveloped his already sluggish senses, maybe he’d ask Sans to join him in his personal lab tomorrow. Just as a temporary station. He imagined it’d be good for Sans to work away from the rest of the staff so there'd be less pressure on him, and Gaster would be able to coach him without his son worrying about any expectations. The only thing Gaster expected of Sans, was that he tried his best, and he'd make that clear in the morning. But for now, he'd sleep.

-

An hour later Gaster found himself groaning in his sleep, he felt strange, like there was tingling in his pelvis...

‘Oh.’, he thought, ‘Haven't had one of these dreams in years.’ He chuckled softly and relaxed as he allowed the tingling to form into something solid, letting his dream take the wheel as pleasure began travelling through his body.

He wasn't worried about Sans finding out, his son slept like a rock and never woke up until midday. And Gaster was grateful for that, what he automatically formed when experiencing pleasure, was quite unbecoming in his opinion. But he had always enjoyed the feeling that a vaginal entrance gave his body more than a dick, and when pleasuring himself, would always form the former.

He let out a quiet moan as he felt something solid push up against him and he found himself frustrated that he couldn't feel the contact directly. He’d fallen asleep with his pants on, of course. Nevertheless he spread his legs to allow the opposing pressure easier access and revelled in the sensation of his lips being parted by the solid mass.

“Haaa...”, he heard himself moan and blushed embarrassed though no one had heard. This was amazing! The first wet dream he’d had in forever, and his dream was not failing to live up to its namesake. The pressure pushing against him moved, the mass grinding his pussy through his clothes beginning to become hotter.

A hot breath ladled with magic brushed the back of Gaster’s head.

He opened his eyes, and strangely enough found that the pressure and sensations hadn't ended along with his sleep. Gaster’s soul ran cold, realizing the only one who could be actually doing these things to him was...

Gaster sluggishly turned his head, weighed down by his drunkenness and the now very real weight on top of him. A blue and yellow eye light blazed in the darkness of the room, hazily looking straight ahead at a wall. Gaster’s own eye lights became pin pricked in shock.

His son was on top of him, wasted, but vigorously humping his formed magic with his own. Layers of fabric be damned, Gaster had to stop this.

“Sans! S-Sans stop it! What are you doing? Sans I'm your father, please stop!”, he tried to yell but his voice still slurred and came out as no more than a mumble. Seeing that Sans hadn’t heard him he tried to move, only to realize with a spike of fear that Sans had his hands on top of his, effectively pinning Gaster to the bed as he continued rutting.

“why ya’ gotta be my dad dings...? i love ya’ so much, can’t even tell ya’ how beautiful ya’ are... fuck, an’ i wanna fuck ya’, but ur my daddy so it ain’t allowed... daddy. daddy, daddy, daddy!”, Sans trailed off accentuating every other word with another thrust against his father’s clothed pussy. As Gaster looked up at him, he could tell that Sans wasn’t all there as he was doing this, even as he spoke he sounded far away. Gaster found himself strangely relieved at that, but that didn’t help the fact that he was still being humped and could do nothing about it.

Gaster felt wrong, his whole soul felt wrong. Sans was doing all of this, calling him what he’d called him when he was just five, learning bone magic for the first time. No, no, no, no! He had to get Sans’ attention quickly, make him realize what he was doing. Gaster’s entire soul was screaming for this to end, but at the same time he felt a thought bearing down on his panic. ‘He won’t hurt you. He’s Sans. Sans would never hurt you, just let it happen.’, god why was he thinking like that? This was insane!

Sans’ hot breath was constantly breathing down his neck as his son began kissing it from behind. Gaster just trembled in place, trying to find his voice or enough strength to shout or move at all, but his body felt like lead. He felt an unguarded groan slip out of his mouth and wished he could hold back the ones that followed afterwards. While Sans rutting against him disgusted his soul, it was still pleasuring his body. His groans turned into moans as he realized in muted horror, it still felt good. The part of him that wanted him to stop panicking and just lie back and allow his son to practically fuck him, was overwhelming his senses and winning. Even the disgust in his soul was soon wrangled in by the pleasure and desire that lurked in his mind. “Nnaah!”, he moaned out pitifully.

Sans humped him groaning out all kinds of sinful thoughts out above him that made him blush and want to hide. How Sans wanted to fuck him in his office bent over his calculations, how he wanted to make love to him in front of the entire Underground, how he wanted to eat Gaster out for breakfast lunch and dinner, how he wanted to fill Gaster up with his cum until he bore his young. Gaster groaned out weakly, knowing that even though his son was not lucid, that everything he said was still a part of his subconscious. No one just came up with these things on the spot, his son loved him, in all ways that he shouldn’t, but he did.

He gasped let out a quiet whine as his pussy throbbed, he was so close. He laid there, helpless as Sans’ thrusts brought him to the edge without him moving at all. “Hah! Ah, haaa... Sans!”, he keened as his orgasm hit his entire being like a wave. And it was amazing, his mind buzzed as he rode his high. He didn't have much time to think of anything else before Sans sped up again. He just moaned as Sans’ thrusts against him sped up, and sped up, and sped up, and he felt a spurt of wetness through his now soaked pants. “Gaster...”, Sans whispered his head collapsing next to Gaster’s in exhaustion.

Gaster then felt all of his energy put into staying awake, leave his body as Sans stopped and his consciousness faded into nothing, passing out on the spot. Sans wasn't awake for much longer, feeling suddenly exhausted for some reason, and passed out next to his father.

-

Sans woke up the next day with a pounding headache and an aching body and groaned out loud, okay. Drinking with his father, okay. Drinking himself stupid, dumb. Fuck, why had he let Gaster order that second bottle?

He knew why in his mind, it was near impossible for him to refuse his father, even more so when he looked at him like that. Though that was the first time he’d seen that particular look on his face, so he’d had no time to even think about refusing.

Sans slowly opened his eye sockets and was glad to note that the room was dark, for he would have cursed had even the tiniest light been on. He was squinting as he stared across the room, trying to remember if the guest bedroom in his father’s home had ever had such an ornate wallpaper in it.

No...no it hadn’t...

A sharp intake of breath and sudden movement right next to him shocked Sans into an upright position, scrambling to see...

Gaster, looking like a mirror of his position at the moment, shocked, confused, wary...but unlike him, scared. Why was Sans in his father’s room? He remembered being dropped off in the guest bedroom late last night, so why?

Sans blinked slowly as he started to observe his father and himself a bit more closely, shaking away his groggy state of mind and disregarding the pounding in his head. Oh fuck, he began to sweat as he found he had new questions the more he looked. Why were his pants sticky? Why did Gaster’s pants seem damp in the same area as Sans’? And why was Gaster looking at him like...? Like he had done something horrible?

His soul felt heavy and he clenched his hands as he backed off of the bed, keeping eye light contact with Gaster as he raised his hands and backed away till his back hit the corner of the room. He had no idea what was going on, but...he felt sick to his soul as he had a pretty clear idea from what he’d gathered. Gathering his strength he spoke, “i...i don’t know what happened last night dad... but if it’s... if i hurt you, i’m so fucking sorry! i...i don’t even-!” Gaster stopped him.

“You weren’t lucid.”, he stated simply as he seemed to try and compose himself not moving from off the bed. “You can come back, I know you won’t do anything Sans.”

Sans didn’t move for a moment before hesitantly coming back to stand by the bed, not feeling comfortable enough to sit. He looked to the bed sheets, “so i did hurt you...”

“No...you didn’t hurt me.”, Gaster said resolutely before his voice became quiet again, “I think you were sleepwalking Sans, you had no idea-.”

“that doesn’t make it okay! don’t talk like it’s okay what i did to you dings!”, Sans shouted tears surfacing in his eye sockets. “i fucking walked in here, lucid or not and...fucking raped you, it’s not-!”, Sans suddenly lost his voice as Gaster reached out to him and placed a gentle hand on his cheek.

Gaster’s eye lights were tired but determined as they stared into Sans’, “You did not rape me Sans. Regardless, no matter what you did, I know it will not happen again. Because as I discovered last night, you love me in ways...I never thought you did.”

Sans glanced off to the side clicking his teeth, “doing what i did doesn’t equate to love.”

“I agree, but you talked while you slept. You told me...”, Gaster blushed as he finally looked away from Sans, “Of all the things you loved about me, and wanted to do with me...”

Sans sputtered as this news hit him, “i, i what? fuck, dings i’m so sorry!” Gaster just shook his head slowly and Sans frowned, “how are you so calm right now?”

His father shrugged sighing, “I honestly don’t know...I think...” He thought back to last night’s occurrences, going to his last coherent memory before his blush darkened. He had started to like what Sans had been doing to him near the end, but he shouldn’t tell Sans that. This had to be put behind them. He shook away his blush, “I think I still trust you, even after...”

Sans’ eye lights studied Gaster’s face for a moment before dilating as he finally came closer, “you still trust me...?” Gaster nodded. Sans then sat on the bed, “you trust me to be near you?” His father nodded again and Sans moved closer to hover by his side, watching his face closely. “you trust me even to touch you?” Another nod before Gaster felt Sans’ hands come up to hold his face and gently turn it to face him, he felt his soul flutter in fear and excitement as Sans’ eye lights filled with potent magic bore into him.

“you trust me, even if i still love you more than i should? even if my love extends to lust, even if my love might be more than you can bear?”, Sans’ voice became haunted and his expression empty tinged only with desire for the monster in front of him, “ ‘cause i’m gonna warn ya’ now, i don’t care if we start doing this or not, i ain’t gonna force you. but i don’t like sharing gaster, you understand that?”

The look in Sans’ eye lights was wild but calm, reserved but in a way unhinged, and Gaster felt a shudder travel through his entire being in excitement as his soul throbbed in desire. He didn’t truly understand why seeing Sans like this made him want him, but he wrangled in the sensation and he nodded. “I...I don’t want to do this Sans, you’re my son. But I understand, and I still trust you.”

Sans’ expression mellowed out in moments and he released Gaster’s face backing away again, “so...stupid question, but are we good?”

Gaster nodded stiffly, “Yeah. You should go home for the day. I need to rest, and you need to make sure Papyrus got to school okay.”

Sans nodded and sat in place for a moment before teleporting out of the room. Gaster’s head was spinning, “Fuck.” He hadn’t been lying, he didn’t hold anything against Sans, but still... “Fuck.”, he said again. What a mess.

Chapter Text

Post Core Conception: 1 Years 1 Month

Gaster was perplexed.

It had been a month after what he referred to in his mind as “The Incident”, and he didn’t know why he was feeling this way. Not fearful or angry, but something he couldn’t quite define. Gaster himself never held anything against his son for what happened, but there existed a pressure Gaster could practically feel whenever Sans had to be in a room with him alone. Which was quite a lot now.

Gaster was a genius. But Gaster was also an idiot, having no idea why he’d gone through with the plan he’d come up with a month prior, relocating Sans’ workstation to the lab he worked in. He thought that removing any outside pressure would help Sans to thrive before the incident, and didn’t see how the incident would change that fact. It only made interactions and coaching unbearably strained. Everything that happened between them was strained now, and Gaster hated it.

He wanted to be able to coach his son without feeling this pressure to say more than he was. And when the pressure would lift after hours of silence between the two, they would say a passing comment, or walk behind one another to reach another station in the lab, and the pressure would bear down again like it'd never alleviated at all.

He wanted things to stay the same as they were before the incident, which is why he was grateful to his son. Sans never brought up the incident, and never did anything he hadn’t done before. He still made jokes, he was still laid back when he worked, and these things brought some peace to Gaster’s mind.

Yet he still had questions.

So many questions plagued his mind that he wanted to ask his son, and sometimes his curiosity would override his desire to forget the entire debacle. The two would be sitting in silence next to each other, watching readings from the core on their computer screens.

And Gaster wouldn’t be able to keep his mouth shut for long, and there was only so much he could do before he’d have to sit down and actually do his work. “What...”, he started without taking his attention away from the screens, “What did you mean by...you ‘don’t like sharing’?”

Sans didn’t react for a minute before shrugging, “i meant what i said, i don’t want you with anyone else dings...” Since the incident, whenever they were at work Sans would call Gaster the nickname he’d given him instead of “dad”. Perhaps it was to make Gaster more comfortable, but Gaster didn’t know if it made things easier, or just made him sad.

Gaster nodded at Sans’ answer, but still couldn’t put the thought to rest. Thinking back to it... Sans kneeling over him, holding his head in his hands, the way he looked at him when he’d said those words... Looking back at it from an outsider perspective, the statement seemed more like a threat than anything, and if he had been threatened he didn’t know what he’d do. If Gaster was in a situation where his safety was on the line, he’d either have to have Sans locked up for both their protection, or live under the thumb of his son for the rest of their lives. Neither solutions seemed viable to Gaster, but he had to get to the bottom of his worries. Steeling himself he spoke again, “What would you do if I did start dating someone...?”

Sans’s head swiveled over to stare at Gaster intensely, his father visibly shuddered at the coldness that radiated from his son’s eyes. Sans’ eye sockets slimmed only very slightly, “theoretically.” It wasn’t a question.

Gaster nodded and spoke quietly, “Theoretically.”

“I’d kill them.”, there was no hesitation or wavering in his son’s voice. Just rigid cold and determination. Gaster’s magic ran cold, but he had no opportunity to say anything more before his son stood and approached him.

Only sitting five feet away, Gaster had no time to stand and retreat before Sans placed a hand over his own with a tenderness that didn’t suit his following confession, making him freeze. He’d gone through war, he’d gone through loss, he’d seen families torn asunder, and heard more violent statements than the one he’d just heard from his son, soaked in grief, vengeance, and a thirst for blood. But it was this, his son flatly stating that he’d kill anyone he dated, tear out their souls, and leave not even their dust left, all into the side of the trembling scientist’s head, that left his soul feeling frozen over and his body tingling in excitement.

A click of bone snapped him out of his frozen state and he opened his eye sockets, not realizing he’d closed them at all. Sans’ teeth were pushed against his cheek in a sweet kiss, and Gaster found himself surprised that it didn’t feel wrong, he didn’t even feel compelled to push Sans away. After a moment Sans pulled back slightly and Gaster saw life in his son again as he brought his other hand up to cup the side of his skull, resolutely meeting Gaster’s eye lights. “i’d kill anyone who ever dared to love you the same way i do... but I would never hurt you dings. ever. i’d rather dust.”

And with that, Sans left his side to sit back in his chair, and begin going over calculations that went across the screen. It was unprecedented to Gaster, having never before heard of such possessiveness as this. His talents were in engineering and chemistry, not psychology. He had no idea anyone could feel this way about him, and he had no inner understanding about why it excited him so much, why it thrilled him in ways he never thought possible. And it was wrong. Gaster knew it was wrong, but as he turned to his own screen again, he blushed and felt a wide smile creep on to his face as his soul felt utterly uplifted.

How did he have the audacity to be flattered by that, to be embarrassed, to find it sweet? He didn’t know how, but he did. And he realized, when Sans had told him he didn’t like sharing, it wasn’t a threat directed at Gaster. It was a warning for him. And while the rational part of him named it sick, his desire skipped naming what it was all together and was okay with it.

After this particular instance, things changed over the following three months. The questions Gaster would throw at Sans would increase in amount, and decrease in time in between each one. It had come to a point where Gaster had to seriously consider if he even wanted to forget about the incident anymore. He was asking questions every week now. He was asking small questions, big questions, wanting to hear more about why Sans wanted him, and sometimes even how. And nearly every time, Sans would answer him without a fight.

When Gaster dared to ask Sans intimate questions, the room would always seem to become smaller and more intimate when Sans chose to answer, those being the only questions he would sometimes dodge. When he did answer and when he finished speaking, either he or Gaster would have to leave for ten minutes to clear their heads or “take care of something”.

Another thing that had changed, Gaster’s mind. Gaster was seriously considering looking into the existence of hidden mind control magic, because at nights when he’d get needy. It wasn’t a nameless face pleasuring him like it would always be before the incident, it was Sans. He’d imagine the skeleton doing all the things his answers in the lab entailed, hell sometimes he’d even think back to the incident. He’d imagine that Sans would keep going further than he did, full on fuck him into the bed, grunting by his head with each thrust while he laid there helplessly moaning into the bed sheets like the whore he-. “HAAAh! Nnnn!”, Gaster’s moans filled his bedroom as he trembled from the orgasm racking his body that had yet to subside. He pumped his fingers inside a few more times, revelling in the lewd sensations with a few desperate whines.

Gaster panted softly into his bed and removed his fingers from his entrance, blushing hard before rolling on to his side, and tried to hold back his tears. He wanted Sans...but he hated that he did.

It was to be expected, Gaster had become addicted with the thought of being desired. The feeling of belonging to someone was intoxicating, he could not deny. But... “Aaaaaagh!”, he screamed only for his voice to trail off into sobs. Sans was his son. In his mind he’d stopped calling him as such as soon as he’d decided he wanted him, but he couldn’t have him, could he? He didn’t even know if what he felt for Sans was just lust and the natural parental love he’d already had for him, or actual romantic love.

He wanted to be near Sans, he wanted to kiss him, he wanted to hear all of his stupid jokes, he wanted Sans to hold him close... Gaster cried himself to sleep, just wanting someone to tell him what was going on inside his head. He cried into the abyss.

But nobody came.

-

A few knocks on the front door called the attention of the monster sitting inside the house. Having been working he placed down his pencil and went to the door to open it.

“DADDY!”, Papyrus shouted happy to see his father this early in the morning. He launched himself at the much taller skeleton standing there and hugged him.

Gaster smiled and grunted at the force the small skeleton had hugged him with, laughing he hugged the eight year-old with just as much strength before letting go again. “Heya Paps. Is your brother up yet?” Papyrus shook his head before letting go of his father’s waist to step back and allow him in the house. Gaster closed the door behind him, taking in the living room. A coloring book was placed in front of the tv unopened, while a lined notebook sat next to it, its pages filled with pencil drawings of strange contraptions that Gaster was sure not even he could build. He smiled, walking over to look down at the book.

He gave Papyrus a wide smile, “What’s all this?”

The little boy ran over to grab the notebook and shut it closed, trying to hide his work. Gaster snickered at the sudden burst of speed, had he ever moved so quickly? Papyrus stood on top of the notebook, making sure it stayed closed. “THEY’RE MY BLUEPRINTS! YOU CAN’T LOOK. NOT UNTIL I CAN BUILD THEM!”, the little skeleton declared proudly but sternly.

Gaster nodded in understanding, “I completely understand. But when you get to the building, you’re going to need help Papyrus. You know who’s really good with engineering?”

Papyrus shook his head vigorously, “NO NO NO! I KNOW YOU AND SANS ARE GOOD AT IT, BUT I WANNA BE GOOD AT IT TOO! SO I NEED TO DO IT MYSELF.”

Gaster kneeled down placing a hand on Papyrus’ shoulder, “Even your brother and I need help sometimes. When I first built something, I had to get help or else I never would have finished it. I needed help, and for years after that needed help with everything I did. It’s only rarely that I ever build something by myself Pap.”

His son nodded his lower jaw clipping over his top teeth in what Gaster recognized as a pout, before he looked up at him again. “WELL, CAN YOU HELP SANS THEN?”

Gaster tilted his head at that, before remembering. Before everything that had happened between he and Sans, he had mentioned a personal project. Gaster sighed and nodded, “I will Papyrus, he doesn’t sleep much does he?”

Papyrus just shook his head. A voice called from the second floor landing in a teasing voice, “my ears are burning.”

Both Papyrus and Gaster looked up to see Sans slowly making his way from his room to the stairs, yawning into his hand. Gaster stood and Papyrus stomped his foot declaring loudly, “SKELETONS DO NOT HAVE EARS!”

Sans closed his mouth as his yawn faded, keeping his eye lights on Papyrus as he came down the stairs and towards them. “oh? oh right, sorry paps. i’m such a bonehead in the morning, heh.”

“NO!”

“aw pap am i gettin’ under your skin with my awesome jokes?”

“NOOO!”

“man pap, if i keep going on like this i’m gonna run bone dry here!”

“UGH! DADDY MAKE HIM STOP!”, Papyrus finally broke turning to his father for help. Gaster covered his mouth with his hand for a moment in thought before reaching out with two fingers to poke Sans’ skull, lightly pushing it back.

“Knock it off.”, he said with a smile. Sans gave him a surprised look before smiling widely. That was the first time Gaster had touched him since the morning after of the incident...

“welp, can’t argue with that.”, he shrugged.

“BUT YOU CAN ARGUE WITH ME...”, Papyrus deadpanned in ire.

“yup.”

It took all of two seconds for the brothers to start up again before Gaster smartly decided to retreat to the kitchen and get started on breakfast. He was the only one of the three that knew how to cook yet and he sincerely doubted that Sans would ever take it up. He’d have to give Papyrus lessons later on when he was a little older. As he got together ingredients from the fridge and cabinets, he listened to the bickering from the other room and smiled.

In a perfect world, Gaster would have been a social hermit. He did not like leaving his house, and he did not like talking with as many people as he had to, but there existed overrides for his natural want to stay home. One was his family, the two skeletons bickering back and forth in the other room. And one was his work, and often the lab would become much like his home, too attractive to leave and face the outside world.

And in between both, was his private home. He stayed there often and every other week or so he’d come to see his sons. He just hoped that Papyrus wouldn’t grow up thinking that he didn’t love them. After all, last time Gaster had stayed with them for an extended period of time, he could feel himself about to snap. Every little thing would nearly set him off, and he became scared that if he didn’t find some place of his own, he’d end up shouting at his only family just for turning on the tv with him in the room. So a private home it was.

Sometimes Papyrus would sleep over his house for a week, which Gaster considered a safe duration and did not want to push to see if he could go longer. He’d rather be safe than sorry.

With a sigh, Gaster peeked out of the kitchen a half an hour later. “Breakfast is ready. Sans, let go of your brother.”, he scolded seeing his oldest holding Papyrus’ screaming head in his arm as he noogied him.

With an amused grin, Sans complied and walked into the kitchen. “okay fun police.”

Papyrus groaned and charged right after and Gaster stopped him simply holding his head before he could advance, “BUT DAD!”

Gaster chuckled, “No more fighting, you two shouldn’t fight alright?” Papyrus pouted and stomped his way into the kitchen muttering his reluctant agreement. Gaster then turned to look at Sans already sitting at the table, “Alright Sans?”

The skeleton glanced his way before shrugging and popping a piece of pancake into his mouth, “kay dings.” He grinned at Papyrus as he sat next to him and laughed when Papyrus stuck out a magic tongue at him in response.

Gaster watched them for a moment before he moved to sit and eat sitting opposite his sons at the table, dreading what he knew was coming later, and savoring the peace he felt right now.

-

Papyrus hugged his father as he got ready to leave the house, his backpack fastened to his back and wearing a red jacket that covered his casual clothes underneath. Sans stood by the door waiting patiently as the two spoke, hands stuffed inside his pockets. He knew once he’d dropped Papyrus off and came back home, Gaster had something to say to him. There hadn’t been anything especially telling of this fact outside of Gaster’s micro expressions that Sans had noticed. There hadn’t been any special or secretive looks they exchanged, Sans just knew.

He was never really an open book and neither was his father, but Sans was attentive. Attentive is what he called it, though if others knew, they’d refer to his talent as obsessive.

He could read his father perfectly, with his body language, elegant even when angry, with his stony expression that would change to sweet or somber in an instant, his eye lights filled with life even when exhausted. Sans knew everything there was to know about his father, just not how to express his true feelings towards him without fucking things up.

Papyrus bounded over to Sans’ side, “BROTHER! C’MON, SCHOOL TIME! SCHOOL SCHOOL SCHOOL!” His brother’s enthusiastic cheers brought a smile to his face and he placed a hand on his head to stop his hopping.

“alright alright bro, chill. c’mon gimme your hand.”, he held his hand out for Papyrus to take as he opened the front door. His little brother grabbed his hand and basically pulled him out the door, obviously not in a mood to tolerate his brother’s slow pace. The door hit the door frame but did not close completely.

Gaster watched distantly as the front door bounced open and allowed the cool Snowdin breeze in to hit his legs, he simply stared for a few minutes, before finally going to shut the door fully. A heavy sigh freed itself from Gaster’s mouth and he turned back to the now empty house behind him. “Okay...”, he spoke aloud trying to calm himself.

“okay.”, he jumped when a deep voice echoed him. He didn’t need to turn to know it was Sans as the shorter skeleton came up behind him with a sigh.

Gaster exhaled sharply and sighed, “I...I wanted to...” Gaster shook away his nervousness as best as he could, which wasn’t very effective, his soul stubbornly glowing nervously in his chest. He turned to slightly face Sans, “I wanted to speak, with you Sans.”

His son stared at him for a moment before nodding and making his way to the couch, wordlessly he waved to the rest of the couch, offering a seat to Gaster. He looked...not calm but, accepting. Like no matter what came of this conversation, that he’d be okay with it, no matter how shitty the outcome.

Gaster hesitantly sat on the opposite end of the couch, hyper aware of his every movement. His mouth felt dry as he tried to speak, everything he would try to say not sounding right, aggressive, not aggressive enough, too kind, too angry. He repeatedly closed his mouth almost immediately after opening it wringing his hands in his lap.

Sans watched in concerned silence as his father seemed to be scrambling to remember how to speak until he couldn’t take it anymore. “dings...”, Sans started delicately. His father looked at him for a long moment, and Sans watched in dread as his emotions build up all at once and burst.

“How are you in my head?”, Gaster finally yelled with tears building in his eye sockets. Sans, not expecting a question like that just blinked in response. Gaster didn’t wait for an answer far too upset to stop, “Every time I decide that I can handle it, ‘Now, now I can forget all about it’,  you somehow get right back in my head and suddenly you're all I can fucking think about! I shouldn't feel like this. You, shouldn’t feel like this! I can't even touch myself without thinking of you! Why can't I just fucking forget!”

By this point Gaster was crying, hitting the couch whenever his confusion, anger and sadness spiked. He whined as his hands came up to hold his head, “I don't even know if I love you the same way. We won't be able to do anything unless we hide. It's all pointless so why, why, why can't I stop wanting you? What do you want? You act like nothing happened just fine, then you look at me like you did that night... I don't even know what I want anymore. You're so...so goddamn confusing!” He trailed off feeling all of his emotions he’d bottled up over the past months come down on him in one moment, sobbing with his breath hitching.

Sans felt his soul burning seeing Gaster cry, feeling upset knowing this was his fault. He frowned and stood to go to Gaster’s side and hesitantly wrap his arms around his crying father. “i...i’m sorry dings, for everything. i never knew you were feeling like i was toying with you or anything. and i dunno what you mean about me being in your head, honest.”, Sans started lowly before blinking in surprise and tensing up, feeling Gaster wrap his arms around him and cry into his jacket. Sans’ soul fluttered as his mind scrambled searching for the right response to the sudden display so he would comfort his father and not cause the opposite effect to occur.

Sans settled with patting his father’s back slowly for a minute before continuing, “i know i shouldn’t feel the way that i do for you gaster, believe me when i realized for the first time i...i tried to reason with myself for months on a hundred reasons why i shouldn’t. but no matter how much i ignored it, every time i saw you, all i could think was... ‘he’s the most beautiful person i’ve ever seen’ and all rationality was cast aside, just to love you. and after that night...i wanted to help you forget it, i felt like if we could pretend long enough you’d forget about my feelings too and everything would go back to normal. but you moved me to your work station, you kept bringing up how i felt for ya’ what i’d do to ya’ if we could be together...” Sans shook his head with a sigh meeting Gaster’s eye lights as they looked up at him and smiled sadly, “and...to be honest i dunno if what i feel for you is genuine romantic love either, ‘cause i know i’m fucked in the head dad. what i said about keeping you to myself? i meant it, i knew i was probably scarin’ you with what i was saying, but that sick part of me really wanted to scare ya’, just so you wouldn’t...anyways. i figured if i felt strongly enough for you to want to kill any fucker that put their hands on you, it must be love. maybe not, but i like to think so.”

Gaster had stopped crying at this point, and just let himself be held, he felt Sans’ hand on top of his skull, gently petting him. His mind felt lighter now, not so clouded with emotions and confusion. But his soul still ached, “I'm not...as smart as I say I am sometimes. I...did want to forget, but moving you to my work station was a dumb idea. Having you that close in a place no one could interrupt, pushed me to ask you about everything. And knowing everything made me want you... I never considered how you felt, putting you in that position, it must have been Hell. Sans, I'm-.” Sans interrupted.

“don't. gaster do not apologize to me. after what i did to you...”, Sans looked off to the side.

Gaster frowned and pulled back from Sans’ embrace enough to look at him face to face, “You don't even remember what happened Sans. And I forgave you the morning after remember?” That didn't seem to dissipate the guilty look on the other skeleton's face, Gaster sighed. ‘No time like now to tell him’, he thought. “Besides, I...I kinda liked it after a bit...”, Gaster’s eye lights darted away from Sans’ face as soon as realization hit it.

“what.”, Sans stated.

Gaster felt his skull become hot, he nodded. “I...You were humping me in my bed and...o-our magic was formed--but our clothes were on so there wasn't direct contact! And...f-feeling you, even through my pants...st-st-started to t-t-t-turn me on... S-so I liked it! It may have been scary at first, but I knew you wouldn't hurt me and my rationality, kinda shut off to f-feel you and the pleasure.”, by the end of his explanation Gaster was sure his skull was on fire. Flushed lilac and still being held in Sans’ arms, he was terrified to see Sans’ expression.

He started when he felt Sans’ arms tighten around him and he started to look back, maybe it wouldn't be that bad? But before Gaster could even see him, he was pulled forward as Sans pushed his head into his neck. And stayed there.

It took a bit for Gaster to realize that nothing was happening, and Sans was not letting go. “S-Sans? Are you...hiding?”, he asked not trying to move. He looked over to see what little he could of Sans’ skull, and blinked when he saw the faintest tinge of blue.

“give me a moment, dings?”, Sans muttered into his neck.

Gaster smiled at this feeling his own blush still burning, undoubtedly prominent on his pale face, “Gotcha.” He sat trying to will away the embarrassing things he’d just admitted into oblivion to no avail, but he was glad he wasn’t the only one left blushing from it.

After a few minutes Sans began to slowly pull away but before he could get very far, his eye lights happened to meet Gaster’s, and they both froze.

Their souls hummed silently as they stared into each other a silent question hanging in the air. Gaster felt Sans’ hands on his shoulders, shifting and feeling his bones through the fabric. Sans could see the magic in his father's eye lights glowing in unison with his soul, he could feel Gaster’s breaths on his face -- they were so close. Time seemed to have all but stopped right there.

Their souls’ magic reached out, asking for permission, asking to get just a bit closer and...

Gaster opened his eye sockets when he felt Sans’ fingers push against his teeth, stopping the attempt at a kiss before it happened. He blinked, dumbfounded, not having realized he’d even tried to, and hurt that Sans had stopped him. He pulled back with a frown, “...Sans?”

Sans sighed with a sad frown hand still out in front of him, “i want to. you gotta believe i do dings... i just...” He shook his head dropping his hand, seeming frustrated at himself more than anything before looking at Gaster seriously, “you said it and so did i...we don’t know what this is we’re feeling right now. and i...after what i did to ya’ - regardless of you liking it or not - i feel that i owe you the time to sort it all out. maybe i can use the time too. figure out what the hell’s happening in my head. but...” He frowned the magic in his eye flickering in distress, “i don’t wanna kiss you if you don’t truly love me and want it, i don’t wanna kiss you if it turns out i’m just crazy. and i don’t wanna kiss you, love it, and then one or both of us decide that this was a big mistake later. it’ll...it’ll hurt too much.”

Gaster listened to Sans’ words and took them into careful consideration, and he nodded. “I...I understand. I don’t want to wait, but I do not want to hurt you either. So we should both...take our time and, when we’re both sure what we’re feeling is true or not, we’ll talk again.”, he agreed.

Sans nodded and Gaster sighed and started to pull away, he gasped when he was pulled in close again. But unlike before there was no embarrassment in this sudden embrace, it was out of pure desperation. “S-Sans? I thought you, you just said-!”, he started pushing a bit before Sans’ hold tightened but not to a point of being uncomfortable.

Sans muttered his response softly, “this is what i meant gaster. once i do something with you, it's like it becomes impossible to live without it... i’m sorry, i know i just said...just a few more minutes like this. i want to feel you, breathe you... just a little longer, i promise...”

A little longer lasted a little longer than an hour like that, Gaster not complaining the entire time, and not commenting once Sans was able to let him go. Though he was impressed, that was the longest time he’d seen his son stand and not fall asleep. He guessed he had that effect on him, keeping his attention, therefore keeping him awake.

As soon as Gaster could no longer feel Sans’ hands on his form, he hesitantly looked to see his face. Sans’ trembling eye lights were glued to the far wall as he clenched and unclenched his hands a few times, trying to get used to the feeling of not holding Gaster in them. He breathed painfully slow, trying to restrain himself. “i-i...”, he started before screwing his eye sockets shut, “i’ll be back before dinner.” He disappeared without another word.

Gaster let his own hands fall back down into his lap and he took a shaky breath, drawing his knees up to his mouth to let a few tears fall silently. This was for the best, he assured himself.

They couldn’t rush into something as serious as a romantic relationship unless they were sure they wanted to cross this line, this was for the best.

But he missed being held...

“Fuck.”, he uttered into his legs as he shut his eye sockets.

-

For the remainder of the day Gaster restlessly wandered around the house, looking for anything to distract his busy mind. One minute he’d be rearranging the food in the fridge, the next he’d be vacuuming under the couch cushions and the next he’d be calling the lab asking for a plethora of completely unnecessary status reports. He was a walking maelstrom of stress, literally. Whenever he lost focus on any one random task, he would begin pacing back and forth in the living room or on the upstairs landing. In those moments, his thoughts would go at a mile a minute in his mind.

This was a good thing, he thought. Sans may have stopped him from doing the most idiotic things he would ever do. Kissing his son? He groaned in frustration feeling both upset that he hadn’t been able to, and disgusted that he was upset in the first place.

But there was one thing that was for sure, if they had kissed, it would have changed everything. Maybe in a few years they’d be able to look past the things that had been shared at the lab, put the whole question and answer sessions behind them. They were already past the incident that had begun all of this, Gaster hoped, at least. But if they had kissed...

Gaster stopped moving for a moment, his hand covering his mouth remembering how he’d felt for the short moment that his soul had resonated with Sans’. They’d wanted the same thing of each other, the one part of them that couldn’t lie wanted them to connect, wanted them to share one blessed little kiss. Gaster let out a shaky breath as his entire chest fluttered with excitement that was more suited to a teenager than himself. The disgust in his mind quickly bore down on him, but he surprised himself when he was able to immediately ignore it. It was still there, but it wasn’t as strong. He could really feel without feeling overwhelmingly guilty about it.

He smiled a little and in a whisper spoke to himself, “What the hell is going on with me...”

The house phone in the kitchen began ringing making the scientist jump and rush to answer it, he cleared his voice before speaking and just hoped whoever was calling couldn’t hear his blushing. “Yes, hello? Doctor Gaster speaking.”, he spoke a bit too quickly for his liking making him wince right after.

A female voice answered from the other end, kind and polite. “Oh hello doctor! It’s the school, Papyrus wants to be picked up. He says his brother Sans usually does, is he on the way? Aftercare is about to begin but Papyrus has made it, ahem, very clear that he doesn’t want to stay. Would you like for him to stay?”

Gaster went blank for a second before glancing at his watch, shit. He cleared his throat again, “No, no. I’m on the way right now, tell him to wait out front.”

-

“Sorry for the wait Papy. Got lost in something.”, Gaster apologized as he walked next to his youngest son on the way back home. “How was school today?”

Papyrus just smiled up at him, walking with a happy bounce in his step. “SCHOOL WAS FUN! I LEARNED SOME COOL THINGS!”, he answered brightly before frowning a bit looking down at his boots, “THOUGH YOU PROBABLY KNOW ABOUT THEM...”

Gaster frowned, again with this. He needed to pay more attention to how his profession affected those close to him. The royal scientist sighed and shook off the thought to give an encouraging smile, “Come on, you can tell me. There are things I don't know about Paps, you never know.”

Papyrus hesitantly looked up at his father and then smiled when he saw the patient smile his father was giving him, waiting for him to speak. “WELL WE WERE LEARNING ABOUT MONSTER FOOD TODAY, AND HOW IT'S GOT MAGIC IN IT TO HELP OUR SOULS AND BODIES.”

Gaster quirked an eyebrow in confusion at that, “You mean your class learned that right? Because I know I've explained that to you before.”

Papyrus nodded his head, “A LOT OF THE KIDS IN MY CLASS KNEW ABOUT IT FROM THEIR PARENTS TOO! SO WE DEMANDED MS GEEN TEACH US SOMETHING DIFFERENT INSTEAD!” Gaster chuckled openly at the thought of that classroom, undoubtedly descending into chaos from the children's collaborative outburst, and was glad that he had abandoned the school system long ago.

He stayed silent as Papyrus continued his story, “SO SHE STARTED TEACHING US ABOUT OUR SOULS!”

Gaster raised a brow curiously, now that was strange. Even he hadn't been taught about souls until his early teens when he first saw a human... He shook his head dismissing the thought to continue listening to his son.

“SHE TAUGHT US ABOUT SOUL TRAITS AND BOSS MONSTER SOULS! THEIR SOULS ARE SUPER DUPER STRONG!”

As Papyrus continued, Gaster listened. Yes, these were things he knew of course, but he couldn't let his son think he wasn't being heard when he spoke to him. About anything.

“AND DID YOU KNOW THAT MONSTERS CAN TRADE SOULS?”, that got Gaster’s attention. He looked down at the young skeleton, and shook his head honestly.

Souls had never been a big part of his studies or experiments, he knew just enough to be able to know what certain things indicated and looked like. He knew that a monster could remove their own soul for therapeutic reasons, and to survey any damage done to it by emotional stress or trauma. But trading? The idea seemed baffling to him. “Why would you trade your soul with someone? It's the culmination of your being, and you just trade it away?”, he asked in honest confusion.

Papyrus giggled at his father's expression, “THE OTHER PERSON DOESN'T KEEP IT! MS GEEN SAID SOMETHING LIKE...OH YEAH! IT'S FOR WHEN SOMEONE IS HURT OR REALLY UPSET, BUT THEY CAN'T TELL YOU WHAT'S WRONG FOR SOME REASON. YOU TRADE SOULS SO YOU CAN UNDERSTAND WHAT'S GOING ON WITHOUT EVEN TALKING! PRETTY COOL HUH?” Gaster stopped walking as they arrived back home, staring at Papyrus absently.

“Mmh, yeah...”, the doctor uttered before shaking his head and smiling at his son, “That is really cool Paps! Thanks for that, you're really a bright kid you know?” With that he patted the top of the little skeleton’s head which provoked a proud giggle.

“NYEH HEH HEH!” Gaster smiled a little before walking towards the house, asking Papyrus if he'd like to help with dinner for the night to change topic.

In the back of his mind he knew what needed to happen now. He wouldn't wait idly by, they wanted their answers, so why not ask the most truthful part of themselves?

-

“you want to what? dings, c’mon this is already hard on both of us!”, Sans protested as he stood from the couch in Gaster's home running his hands over his face in exhaustion.

“That's exactly why I just want this over with! Sans, this is the perfect solution for this whole situation!”, Gaster tried to convince him staying seated but adamant in his position.

Sans sighed giving Gaster an incredulous stare, Gaster held it until Sans groaned out in frustration and plopped back down on the couch. “why then?”, Sans started, “really, tell me how this will help anything. why is rushing into it blindly suddenly a good idea? huh?”

Gaster let out a slow breath, “Rushing -- as you call it -- is exactly what we're not doing Sans.”

The other skeleton gave Gaster a look of disbelief, “it's been a week!”

“And it's been five seconds since you asked me a question! Now if you'd just give me maybe thirty more to let me answer, then you wouldn't need to be such an asshole about this!”, Gaster rebuked sharply.

Sans frowned but kept his mouth shut, still annoyed but a little embarrassed too. As soon as Gaster was sure Sans wouldn't interrupt again, he took a deep breath, and spoke.

“I don't believe it's wise to leave this up to our minds to figure out what we should do here Sans. As much as it contradicts what I trust in, our minds lie to us all the time, to protect us or those we care about. Now that I know there's a way to use something else directly, I want to try it.”, without another word Gaster reached down to grab the hem of his sweater and pull it up.

Taken off guard, Sans choked and in a frantic scramble of him deciding if he should stare or not, turned his head and blocked his eye sockets. “d-dings! what the hell, give some warning or something!”, he sputtered embarrassed.

“Sans.”, the gentle call of his father brought him back down to earth and he looked back. Gaster's sweater was down, and one hand was illuminated in a glowing lilac light emanating from the purple soul that floated above it. Sans wasn't able to stop staring this time.

Now that it was closer, unrestricted by the form it belonged to, Sans could feel the pull of the soul almost physically, he nearly found his hand going to stroke the precious life force before Gaster called him.

He looked up and felt his soul stir, Gaster looked embarrassed, but a little coy as well? Sans let go of a nervous smile and lifted his own shirt.

A blue soul soon floated in Sans’ open hand, not touching anything, but hovering peacefully. It felt so strange to hold the culmination of all that you were, outside of yourself. It made him feel vulnerable and exposed. But as Gaster reached for his soul, and he for Gaster's, it felt like nothing could harm him, like being welcomed into an embrace that promised nothing but protection and love.

As soon as Gaster's soul was safely in his hand, he was fixated, he didn't want to hurt his father. Not again, not ever. So he cupped both hands under it, making sure it stayed near him.

A warm chuckle brought his attention back up. Gaster was smiling at him fondly, “You're so considerate, I know you won't hurt me Sans, don't worry. Let's...let's put our trust in these alright? It's the only part of us that can't lie.” Sans just stared dumbfounded for a moment before smiling nervously.

Gaster and Sans placed one another's souls in their rib cages where their own souls usually resided. And right away, they could feel everything.

Both of them breathed in sharply as emotions that weren't their own flooded them. And in a way, it hurt.

It hurt in a way that they never thought they could hurt. Why couldn't they communicate these feelings sooner? Why were they so afraid of letting these emotions out in the open? Did they not trust each other? No. Gaster had been right. These feelings were raw, unfiltered, incomprehensibly beautiful, and frighteningly straightforward. It made tears come to their eyes as they hugged themselves, trying to keep themselves together. Their minds had spent all this time, lying to hide and eradicate the existence of these emotions, of course they couldn't trust their minds with this.

Fear, apprehension, love, shame, lust, guilt forgiveness. Everything, over and over. There was such a feedback of just everything. Everything would go through Gaster and his reaction to the everything would go right through Sans, and so on and so forth for quite a few minutes.

They felt Sans’ lingering guilt over the incident be completely forgiven in a way Sans hadn't understood before. They felt Gaster's shame over his lust and want for Sans slowly being diminished, but not into nonexistence, by Sans. Not everything they felt could be completely solved by this, but it could thankfully be addressed.

They wanted to try something, both of them agreed with each other.

Sans with a weary groan shot across the couch to land on top of his father. Their eye lights connected, their teeth clicked together, mouths opened and they were kissing before they could get any words out. And words at this point, were unnecessary.

Their souls were speaking for them. Asking what was alright and what was acceptable in the otherwise hazy moment. Sans wanted to pull Gaster closer, Gaster eagerly gave him permission. Sans’ hands found a comfortable spot on his father's hips to hold in a firm, loving grip.

Gaster was a little frightened at how fast they were moving, Sans comforted him and slowed down a bit. He assured Gaster he wouldn't try to have sex with him right then, he just wanted to make him feel good and be close to him. Gaster felt better about it.

Sans felt like he was on cloud-nine, Gaster smiled and found that he too, felt like he was dreaming, for once free of the self-disgust that usually plagued his mind. The only tears they shed now, were from overwhelming joy of being understood and understanding each other.

Gaster whined out breathlessly as Sans kissed him again and again, his hands holding the collar of Sans’ shirt in a desperate attempt to keep him close. Sans’ hands moved over Gaster's lean hips, stroking them as his body jolted into Sans’ from the pleasure.

They wanted to go a bit further than this, and they dared to try.

Sans grabbed Gaster's belt buckle and deftly undid it, allowing Gaster's pants to slide off before being flippantly tossed somewhere. Sans lifted Gaster's legs up on to his shoulders. The doctor gave a few whines, anxious to know what this would feel like.

A passing thought reminded him to not agree to something so blindly, but as soon as he felt Sans’ breath hit his pelvis, that thought dissipated into nothingness.

A tongue swiped up the tip of his sacrum, he jolted and moaned, quickly biting down on one of his fingers while his is other hand shot down to grip into the couch cushions. Sans let out a sharp breath, now realizing that any pleasure Gaster felt, would course through his body as well. He rolled with it.

Both his and Gaster’s magic sparked and activated, and Sans set upon him without hesitation. Gaster nearly screamed into his hand, eye sockets going wide, eye lights becoming hazy. Oh gods that tongue...! Who knew that a tongue could ever feel so good inside him! And it was Sans’ tongue, fat and long, rich with sparking magic and hitting all the right- “AaahH-HAH! ShiiiIIT!”, he whined into his hand the first word he'd spoken in ten minutes. It felt so good! So sinfully lewd! He could hear his moans peaking and cutting off at all the new and different sensations he'd never felt before. “ShIT SHIT! Ffffuuu...fuck, aahha fuck, FUck, SHIT!”

Sans whined at the eruption of sensations, gods Gaster was sensitive! But he didn't dare stop, if this is what he was making his father feel.

The hand Gaster had been biting fell out as his entire body throbbed with need, his trenchcoat was disheveled, only half of Gaster's arms still in the sleeves. He wanted to rip his sweater off, his body was burning and he felt intoxicated by the heat. But at the same time the intoxicating feeling wasn't necessarily unpleasant either.

His head fell back, his hips twitching and rolling into the pleasure. “Haa! A-a-AHhaaA! S-San-! Sa-ANS!”, the speed and hunger in Sans’ roaming tongue inside him was bringing him close, and quickly. The hand that had been digging into the couch cushions then went to Sans’s head buried between his legs, pulling him closer, wanting more and more of that sinful tongue deeper inside him.

In response, Sans moaned into his pussy and altered his magic to accomplish just that, elongating his tongue to reach a spot inside Gaster that elicited such an animalistic keen from the man, that neither of them would ever be able to forget it.

Sans now was moaning loudly in between Gaster's legs, feeling his dick throbbing inside his pants and his whole body screaming in pleasure. He could barely keep his head in place, the temptation to throw his head back and scream becoming overwhelming, but thankfully Gaster's hold on his skull was unwavering with desperation. Instead, Sans redirected his pleasure into pushing his head further, opening his teeth wider to push his tongue deeper into his father. Oh gods he'd never heard Gaster's voice so loud before! His desperate, drunken moans and pleas were all he could hear outside of his own shallow breaths and lewd squishing noises his tongue was making in the trembling pussy in front of his face.

Gaster began breathing in short gasps in between the moans for more, nearly hyperventilating as he moaned wantonly. “NnnNM! HAAH AH! F-FUCK! FU-H FUCK! CUuuu-ah! I-I'm! CUMi-! C-CU-CUmmING! I'M-!”, he shrieked as he felt his soul cry out along with his body in complete pleasure and ecstasy. His bones shook audibly from the force of his orgasm, he whined as Sans’ tongue kept searching his sensitive hole.

Sans came right after Gaster, with a silent scream into his pussy that welcomed the squirts of cum from his father. His pants were soaked and sticky, his dick still pressing hard against where he had cum, but it soon calmed down as Sans removed his tongue from Gaster.

Both of them panted heavily, Gaster still whining as his head lolled back to rest on the arm of the couch, and Sans freeing himself from his father's now lax grip to sit up and take in the array of new, beautiful emotions to memorize on Gaster's face.

Sans kissed Gaster, their tongues swirled and tasted each other, Gaster could taste his own cum. Oh gods that aroused him more than he would ever vocally admit, but thanks to their souls Sans understood and just smiled into the kiss.

They soon parted, and their eye lights met. They didn't need to speak, but they decided to anyways. “well, you were right. that definitely decided that.”

Gaster smirked and laughed lightly, “Definitely.” He laughed some more and Sans smiled. Gaster understood the smile instantly, Sans hadn't seen him laugh in a long while, he was happy that he was happy. Their souls glowed and beat in unison, in fine tune with one another.

Gaster knew that they couldn't keep their souls like this, no matter how wonderful it felt, it would cause problems. But now since they were in tune with one another, understanding one another would be far easier than before. It would not be as if they could communicate as they were now, but if one of them spoke about their worries or feelings, the other would understand their words more deeply than before. 

They both smiled as they held each other, deciding they could wait at least until morning to switch their souls back. Gaster thought for a moment.

His son was his lover, he was his son's lover. This was fact now, their souls had spoken, and this was the result. He sighed, and accepted it along with the challenges they'd inevitably face. This would be one hell of a secret they'd have to keep.

Chapter Text

Post-Core Conception: 4 Years 9 Months

Papyrus watched as his family looked over some readings that’d just come in through the house phone. After making sure they’d transcribed all the data they’d heard correctly to paper, they hung up to look over what had happened. Papyrus sat back in silent annoyance, not understanding anything they were talking about.

Before the stupid phone had wrung, Sans had been helping him think of cool designs for a costume he wanted to wear for a school play he was going to be in. He’d be playing the part of a princess setting out on an adventure with her friend the bridge troll, to save her little brother from an evil warlock. He’d wanted the part so badly because how heroic the princess sounded in their read through of the play. He hadn’t really cared the part was made for a girl, and neither did his teacher after seeing his audition.

Now some of his classmates however... He shook his head, dismissing the teasing he’d heard when some kids found out about it. The part was cool, the princess was cool, and he was cool so naturally he’d be the only one for the part!

“dings you realize what this means right?”, Sans’ voice brought Papyrus back to the moment. His father was staring blankly at the paper with all the data from the lab, he didn’t respond to Sans.

Papyrus gave Sans a look, concerned for his father, and wondering if there was anything he could do to help him snap out of it. Sans just smiled, “dings, the core hasn’t caused any shorts or blackouts in over two years. man this is a milestone!”

Papyrus watched his father’s face, waiting for a reaction, when he saw tears start to well up in his wide eye sockets. “DADDY? ARE YOU OKAY!”, he got up out of his seat to go to his father’s side to tug on his sleeve.

Gaster blinked and started, “U-uh I...um...” He glanced from his sons, then to the numbers and dates in front of him on the kitchen table. Fifty years. He watched the numbers and the paper become blurry as tears began falling. Fifty hopeless years in the darkness, and finally, finally... “We...We did it.”, he stated numbly before covering his mouth to try and stop what felt like a cry but actually came out as a laugh. “We did it!”, he said again more assuredly laughing more freely now.

Papyrus was confused at the mix of emotions he thought couldn’t be possible until now, but Sans just smiled, watching their father break down in joy and disbelief.

“UM, IS DAD HAPPY OR SAD?”

Gaster let out a laugh and finally pulled his gaze away from the paper in front of him to smile at Papyrus. “Neither.”, he lifted Papyrus into his arms as he stood, “I'm absolutely thrilled!”

Papyrus, taken off guard but happy, let out a startled laugh as his father spun him around in his arms before holding him up. “NYEH HEH! DAD WHAT'S GOING ON?”

Gaster chuckled as he held Papyrus up in his arms and looked over his notes, “You know the core used to malfunction right? Power would cut out, and people couldn't see and make their way around the Underground. Today marked a big milestone in our work!”

His father went on and on but Papyrus was stumped, not understanding a word of it, but happy his father seemed so uplifted. Most days he was so stoic, and quiet. And Papyrus would wonder where he got his own energy from, but seeing his father passionately going into the details of how the core - his life's work - operated and functioned, answered his question in full.

His attention then drifted to his brother when he saw movement in the corner of his vision. Over his father's shoulder he saw Sans’ hand rest on his father's lower back.

Papyrus blinked, and redirected his gaze back to the data on the table. He could no longer hear his father's explanation. He felt something tangled and insidious creeping up in his mind, and he knew he was angry. At his father, at Sans, at his classmates. He was just angry.

But he held it in, at this moment, his father was so happy. And to bring him down with his own emotions? Papyrus wouldn't be able to bear that. So he wrangled his anger in, and packed it away in his soul. He couldn't do that to his dad, he loved him, after all.

“And the constant cooling the ice from Snowdin keeps the core from overheating, creating a perfect power generator for all of Monsterkind!”, Gaster continued explaining and opened his mouth to continue even more before Sans intervened.

“c'mon dings, you're gonna overload the kid if you keep on like that. why don't we go out to celebrate?”, he suggested with a pat to Gaster's back before returning his hands to his pockets. Sans could somewhat sense that Papyrus’ attention had drifted during Gaster's verbose explanation.

Gaster opened his mouth a few times more, as his face turned confused. But after assessing the look on Papyrus’ face, he could see that he had lost his son's attention a while ago. And this was a much needed reminder that not everyone was enraptured in science like he was. He gave a slightly embarrassed smile, realizing how long he had carried on. “Yes, you're right. How about it Pap? Want to go on a picnic?”

Papyrus gave his family a quick look, oh right. It was his turn to happily agree and smile like he normally would, and they'd go out, have fun, and act like a normal family. The little skeleton smiled brightly, “YEAH, LET'S GO NOW!”

That was how he was supposed to sound right? Enthusiastic, loud, impatient, cheerful. Yep, that was the Papyrus that his father and brother knew. So that's the one he'd be.

Not the one that saw right through them. The one that saw them exchange quick glances much too often, the one that saw his brother looking at their father in ways that seemed much too adoring and frankly creepy. Papyrus could never be that Papyrus in front of his father and his brother, he wouldn't allow himself to be.

-

Later that night, Papyrus opened his eye sockets after having laid down in silence for over an hour. Insomnia was haunting his attempts at sleep, and he was starting to wonder if he should just stay up and forgo sleep entirely. He had done it before and been completely fine, but it was only 12:36, he'd have to try again and see.

He reached over the side of his car bed to grab his backpack zipper and sluggishly pull it open. Sticking his hand inside he was able to grab his script and open it. He wasn't reading, it was dark in the room and he couldn't see well without his glasses anyways. He spoke his lines while turning pages, trying to get a feel for the timing as his finger guided him.

He heard voices from downstairs, he closed his play. He stood up from his bed and in an almost autopilot manner, walked to his bedroom door. He stood, and listened.

“i think the kids at school have been teasing him too. the little shits... if they knew what i'd-”

“Don't. Sans, do not, do anything.”

“...what? why? little fuckers deserve it for bullying pap!”

“Hush!” There was a pause, they were waiting to see if Papyrus had woken up. Said skeleton stood patiently waiting for them to continue. “You're too extreme Sans, I know. If it gets to a point where they actually lay a hand on Papyrus, I will handle it. Correctly. Right now, all you can and should do is encourage Pap to go through with it. It's the best retort he can give to them, doing it, and kicking ass on that stage.”

Papyrus felt his soul be uplifted by that statement and smiled softly, his eye sockets stung with unshed tears. It warmed his soul to hear his father so assured in his success, determined to help him achieve it. And despite how much he tried to brush it all off, the kids were getting to him, and he did care what people thought of him.

A few classmates that had claimed to be Papyrus’ “friends” had suddenly started avoiding him after he told them what part he wanted to be in the school play. Only two real friends stayed by his side and supported him, and to have support not only at school, but from home too... It filled Papyrus with more determination than ever.

The little skeleton felt a smile creep onto his face as he felt life enter his body, feeling more like his usual self in moments.

“Plus, if you or I go in there and start acting like personal bodyguards, Papyrus will never learn how to deal with bullies like them on his own. On top of that, people will think he needs protecting, and tease him even more. He needs to be independent, and self assured. We can't coddle him anymore Sans.”

After a bit of silence, Papyrus heard his brother sigh. “you're right...you're right i know. it's just...hard.”

“You're telling me! When I picked him up today, all I could think was ‘when did my little boy get so heavy’!”

“he's grown that's for sure, he's still your son though. that's never going to change.”

“Yeah.”

The couch squeaked and bone clicking against bone resounded through the house, and Papyrus felt a little of the life that had just come back to him, ebb away, leaving him cold. “love you dings.”

Gaster hummed, “I love you too... Ah I've gotta get home.”

“checking on the core just in case?”

“You know me well. Bye.”

“i can walk you home after. teleport you if you want.”

“If you come home with me, I don't think you'll let me actually sleep.”

“oh, i'll let ya’ sleep, trust me. might take a bit of effort but i can leave ya’ fucking exhausted if ya’ wanna sleep.”

“...I...If I don't wake up on time, you're working extra hours.”

“yes, s i r...”

There was a moment of silence through the house before there was a spark of magic, silent, but tangible in the air. They were gone. Papyrus took a deep breath, wiped his face, and exhaled.

Calm down.

The two were off to Gaster's house, likely to have sex. His brother would be home later than usual in the morning, but Papyrus had started to walk to school by himself anyways so he didn't care. Sans was always ecstatic after nights of sex with their father so it gave Papyrus ample opportunity to come up with ideas to throw that off.

He often thought of pranks where he'd ask Sans or his father how they enjoyed their night and watch their faces for the reaction. Or he'd ask them how two people had sex - a question he already knew the answer to - , and then when they'd answer, he'd ask them if they'd ever had sex. They could play off some of these things, but imagining that initial panic on their faces, is what made the little skeleton giggle. He'd likely never actually follow through with them, after all, he'd only get the reaction once. It was just fun to imagine.

Papyrus turned to get back into bed and pick up his play, he began reciting lines again, and planned to try his hand at sleeping again in a little while. The twelve year-old had a big day tomorrow, school, then rehearsal. And he'd kick ass in both.

-

“Hey faggot! Going to practice?”, a loud voice called down the hall at Papyrus’ retreating back.

The little skeleton tightened his arms around his binder and ignored the boy, continuing to walk. Annoyingly enough however, the boy shouting at him began to follow him and the kids around him started to either look on in pity, or laugh.

Papyrus believed in what his father had said last night, he did. Retaliate by doing his best and being the best princess he could be in the play. “Yo cock-sucker, you listening?”, the boy now walking in time next to him whispered far too close to his head. But man this asshole was annoying.

“Hanim!”, the principal’s voice called from further down the hall making both boys stop.

Papyrus glanced from his canine principal, to the monster next to him. A gelatinous humanoid monster, made of green slime with “hair” that covered one side of his face, making only one of his white eyes visible.

He’d been the one of the first kids to start bullying him about his play role, so his name was Hanim. Papyrus then decided to say something, with a sweet smile he turned to face the boy who looked at him in confusion and aversion. “WELL LIKE I WAS SAYING HANIM, THE SHOW WILL BE IN TWO MONTHS. THE 23rd, AT 6pm. HOPE TO SEE YOU THERE.”, and like that Papyrus left. Walking straight past the principal and to his next class, leaving Hanim dumbfounded, and the principal confused.

With a soft laugh to himself, he decided, he rather liked acting off-stage. He already had to do it around his family, and he enjoyed doing it on stage, why not see how far he could take it?

For the first time in a while, Papyrus was excited for the rest of the school day, as he imagined all the ways he could hone his acting talents using the people around him.

Chapter Text

Post-Core Conception: 6 Years 8 Months

Murmurs filled the school hallway as the gymnasium door burst open and two monsters tumbled out and onto the floor. Following them was the sound of clamoring as a few more monsters walked or ran out into the hall. One stood in the middle, scowling at the monsters on the floor with blood on his knuckles, from one or both of the other kids. The rest of the group seemed unmarred as they stood behind this unforgettable person who many kids recognized as the school’s “Queen Bee”.

He walked the halls with his head held high, large shoulder bag hanging by his side with school books and a script for whatever play he was in this time inside. He wore a white sweater with ornate red patterns that he had altered himself, it had one sleeve that reached over his fingertips on his left hand, while the other sleeve of the sweater was just gone, the hole where it once was was hemmed so it was a clean line. Simple black leggings and red lace up boots completed the outfit. It was a look, but one that surely only he could pull off.

And many questioned if, since he was a boy, he should be called a “Queen Bee” as he was. But they could find no better title for him, he was a queen in every way. Elegant, strong, popular, but most importantly he was kind. He did not support or stand for rumors, slander, or teasing.

He’d often leave his group of admirers and friends to go speak to someone he’d heard had been recently teased or bullied, and make sure they were okay. Many times he’d try to befriend them, knowing that many bullies did not want to be on his bad side.

As many were reminded of in this very moment, this queen bee was not a perfect student. It wasn’t unheard of that he’d be sent to the principal’s office for getting into fights with bullies.

“ Papyrus! ”, and it seemed the same would be happening today. The fourteen year-old skeleton turned to look at the principal, she hardly looked shocked, more exhausted than anything. This had been the fourth time this year, and they were nearing the end of the semester, she’d probably been hoping last time’s threat of suspension would be enough to prevent another fight.

Papyrus’ face was blank as he wordlessly walked over, waving back at his friends, and then the bullies with far too bright of a smile for it to be friendly. He then stood by the principal, not looking sorry at all.

She sighed, obviously suspension was the only option then. Expulsion wasn’t really possible, since they had no desire to get on the bad side of the Royal Scientist. And speaking of... “My office, now. I’m calling your father,” she ordered.

“YES MA’AM,” Papyrus left to go to the office but first stopped at the bathroom to wash his hands, they’d been filthy.

-

Gaster adjusted the collar of his button-up as he swiftly walked towards the principal’s office, he had been at work when the call from school came in, so he still had his lab coat on but thankfully he hadn’t been working with any dangerous substances. His eyes glowed strong with anger, he just didn’t understand. This had been the fourth time he’d been called this school year, the sixth time in general about something like this. What was Papyrus thinking?

He acted like normal at home, but then came to school and suddenly was looking for fights! Gaster understood that his son had been teased, and that would likely make him empathetic to kids that were also being teased, but damn it he didn’t need to fight anyone!

Gaster opened the door to the principal’s office and immediately saw his son sitting in a chair against the wall. He gave a sigh, Papyrus didn’t even look like he cared that he would get suspended. After such a multitude of incidents like this, Gaster had it firmly in his mind that Papyrus felt that as the son of the Royal Scientist, he could get away with whatever the hell he wanted. That thought pissed Gaster off, but it also got him thinking.

Gaster raised a hand as the principal opened her mouth to speak, he then leaned back on the door to close it, not moving to sit or go to Papyrus. “Please. I understand that Papyrus was warned, and he knows what he pulled today. I know he will be suspended and he’ll be expected to complete all homework regardless, but I have a request.”

The principal, pleasantly surprised that the doctor had taken charge of the conversation, and open to hear anything that the boy’s father thought would help the situation, nodded. “Go on?”

Gaster stood for a moment, staring at his son. “Papyrus?” he asked calmly, his eye lights glowing softly.

Papyrus didn’t respond, staring at the wallpaper across from him instead.

The scientist nodded once and spoke aloud, “Okay.” All in five seconds Gaster scooped up Papyrus’ bag that had been sitting in a chair next to him and unzipped it, his son’s eye lights darted to him, obviously confused. Gaster reached in and pulled out the script for that semester’s play and held on to it.

Papyrus’ hands gripped into his leggings as he watched his father take his script in both hands move to tear it in half...and then stop.

“Papyrus,” he looked up at his father whose eyelights were nowhere to be seen. Gaster put the unmarred script under his arm and crouched down to look Papyrus in the eye sockets, “Do you understand?” His own eye sockets were filled with nothing but dark.

Papyrus breathed in sharply, only now realizing he was nearly crying, and nodded. “U-uh huh...”

Gaster tilted his head slightly, not convinced. “Do you understand?” 

Papyrus nodded more vigorously, “I-I UNDERS-STAND!”

Gaster nodded and stood, “Apologize, and mean it.”

Papyrus quickly stood and turned to his principal, he apologized, only slightly meaning it. Gaster then turned to open the door, and nod towards the principal. “Papyrus will be back, and a model student, six weeks. If not, he’s not performing in, well, anything I suppose. Thank you Mrs. Teil. Papyrus, thank your principal for looking after you.”

Papyrus thanked the principal and then followed his father out of the room, his eye lights focused on the script under his father’s arm.

-

It took a bit for Gaster to calm down and his eye lights to reappear in the depths of his eye sockets, and at that point, he slowed his pace. He realized they were just a minute or so from the house his son and his lover shared, and with long legs and bad mood, he’d been walking quite a lot faster than Papyrus who was just now catching up to him. He felt bad for making his son nearly have to jog to catch up to him, but then again...

Gaster stopped walking as they reached the house, and just stood there.

Papyrus stood next to him, breathing a little heavily and still staring at the script under his father’s arm. Gaster frowned, were the damn plays all he cared about now? Did he not care that this was causing him stress? Did he not want an education anymore? Was he just...too entitled to care?

Gaster then knew what he had to do. He took his son’s shoulder bag which he’d also been carrying but his son didn’t seem nearly as interested in as opposed to his script, and held it out to Papyrus. The skeleton that now reached Gaster’s mid-spine in height, hesitantly took it and put it on with a murmured “thank you”.

“Papyrus. You’re not grounded.”, Gaster stated as he walked towards the house.

Papyrus looked after him in confusion, “I-...I’M NOT?”

Gaster nodded and looked back at him blankly, “Nope. But buddy, that does not mean these six weeks will be anything but a learning experience. You will not be having a good time.”

He turned just in time to see Papyrus’ face fall as he went inside to call Sans.

-

Papyrus stared at his lap, tears in his eye sockets as he heard rustling from upstairs. He wore a regular green sweater, black jeans that were too big on him, and his ugly old red rubber boots. As soon as Sans had gotten home, Gaster had given Papyrus some old clothes he’d forgotten he even had, and told him to change in his room.

As soon as that was done, Gaster made Papyrus sit on the couch while Sans watched him, and Gaster put all his nice clothes into boxes and lined them up outside his room. Papyrus was angry, this wasn’t fair, this was mean! Those were all his favorite clothes he’d have fun with, mixing and matching them to act as characters in his room. And worst of all, his script was sitting on the coffee table right in front of him. He’d been warned not to touch it, or he wouldn’t get to use the TV for the following six weeks either.

Like his father said, he wasn’t grounded, his game system hadn’t been taken away but he noticed the charger for it being packed away with his clothes. Papyrus then realized his father was encouraging him to go outside, but wearing these awful clothes! He wouldn’t do it! People couldn’t see him like this.

And Papyrus couldn’t believe his brother was just standing by and watching! Not arguing, not saying it was unfair, not doing anything! Papyrus then got angry realizing, it was because they fucked that Sans was fine with everything their father said and did. His brother really must not care about him at all then, Papyrus reasoned. This was so unfair...

“Sans, come teleport these boxes to my house please.”, Gaster called down the stairs.

“uh, ok, but uh... pap is crying again. can i uh, or?”

“Oh, I’ll talk to him. Sans, please, and take your time putting them away.”

“ok.”

Papyrus saw his father sit on the couch next to him, the young skeleton immediately moved to stand but Gaster grabbed his wrist and held it next to him, not holding with the intent to hurt, but with the knowledge that he was stronger than his son and any attempt to pull away would do nothing.

Thankfully, Gaster felt, Papyrus didn’t try to pull away and instead slumped back down and looked away. Swallowing a lump in his throat Gaster spoke, “You probably think I'm doing this because I'm angry with you...and I am angry, but that's not why you're being punished like this.”

Papyrus wiped at his tears and sniffed a bit, but said nothing. Gaster continued to explain, “These fights you've been in have made it clear to me that I've been negligent in disciplining you and making you aware of your social standing amongst your peers. For starters, the clothes you own, I bought for you without question when asked, despite you having quite enough nice clothes already. That mistake, I take responsibility for and am already in the process of rectifying.

“As for your standing with your peers, I'm sure you already know many of them regard you with respect, friendliness, and even fear because you are the youngest son of the Royal Scientist. It is only because of my status that it took this long for you to be suspended. You know this right?”

Papyrus clicked his teeth and nodded. Gaster frowned, “Papyrus. Look at me.” His son hesitantly followed directions to look his direction and then slowly looked at his face.

Gaster sighed heavily, “So you know that. But did you know that your standing is not permanent? I won't always be the Royal Scientist Pap. Someday I'll either step down, or be replaced by someone younger and smarter than me. And you will no longer be the son of the Royal Scientist.

“You'll be Papyrus and that's all. And if you spend all your time now as my son, getting into fights, acting, not following rules just because the consequences are less dire for you, that is all that will be left when you're on your own. And that's all people will remember of you, a kid who thought he was above the rules, and did whatever he wanted without being punished. Nothing is permanent, except how people who think they know you, perceive you and your worth.”

Papyrus felt tears reemerge in his eye sockets at his father's words, and looked back down to his lap. “You used to be so bright, cheerful and enthusiastic... I understand that kids change and that's unavoidable but...it's frustrating to not understand what's going on in your head. So I can maybe help you but...”, Gaster released Papyrus’ wrist with a sigh.

“Did something happen Papyrus? Will you tell me?”, Gaster tried even though he was sure nothing would come of it.

Papyrus nearly screamed out in frustration, he and his friends were bad-mouthed all the time, those bullies hurt innocent kids like him, his father and brother fucked behind his back and pretended everything was normal! Everything in his life was so fucked, and his father didn't even notice!

Papyrus’ teeth ground in anger a bit before he stopped himself muttering, “This is bullshit.”

Gaster frowned and looked at his son, “Hey, cut the cursing out, I know this feels unfair-.”

“IT IS UNFAIR!” Papyrus cried in anger, “TH-THOSE BULLIES WERE CALLING MY FRIENDS F-FAGGOTS AND CU-CUNTS A-A-AND-!”

“And that was wrong of them, yes but-!”

“SO WHY CAN’T I DEFEND THEM! WHY IS IT AGAINST THE RULES T-TO SHUT UP ASSHOL-”

“Papyrus! For the last time, language!”

“YOU CURSE ALL THE TIME WITH SANS YOU FUCKING HYPOCRITE! YOU DO AND YOU THINK I DON’T HEAR BUT I DO! SO JUST SHUT UP !”

Tense silence carried on between the two, and in the silence Papyrus started to realize what he’d just said to his father. He was already in enough trouble and he was just making it worse!

“I-I...I’M SORRY DAD...”

Gaster let his head fall into his hands with a sigh, “No, you’re right...” Papyrus looked up at his father as he gave him a weak smile to the side, “I am a fucking hypocrite.”

Papyrus blinked for a few moments and smiled a little, then Gaster went serious again. “Seriously though, don’t curse. Not around me until you’re...sixteen I guess, and not at me, ever again. And never at adults until you’re thirty and have crappy bosses.” Papyrus nodded at the instructions and ducked his head.

In the silence that followed, Papyrus decided to open up a little. “I just...I don’t get it... They’re so mean to my friends, I don’t care what they say to me but-! When they hurt my friends I just...get really angry and...it’s like everything I think is just angry...”

Gaster looked down to his son with a sudden realization in his head, all of these incidents, why hadn’t he sent Papyrus to a child therapist or something yet? He sighed to himself, no time like the present, he supposed.

“I know it doesn’t seem fair, but you’ve got to realize Pap, what those bullies say and do is not your problem. Comforting your friends, going to a teacher, those are your responsibilities as a student. Those bullies are kids, just like you, and they probably have parents that are trying to make them better too, so you can’t just go around beating them up. Or maybe their parents are just as bad -- but regardless!”, Gaster placed his hands on Papyrus’ shoulders and moved to kneel in front of him, “You, are not the mule of the world and all the awful people in it Papyrus. You shouldn’t make yourself suffer the consequences for their awful words and actions. Be a better person, and you’ve already made the world a little kinder.”

Papyrus nodded and wiped his eyes, “Does this mean I get my clothes back?”

“Wait, what? No buddy, sorry. You’ve got to earn them back.”, Gaster stood and turned to pick up the script on the coffee table, “And you have got to care about something besides this. Like the stress these situations put on your brother and I, your education, what you’re teaching the kids around you by trying to solve every problem with violence instead of words. Anything besides your plays.”

Papyrus nodded with a returning spark in his eye lights. Gaster sighed and patted Papyrus on the shoulder before standing, “Now what is taking Sans so long? He better have not fallen asleep.”

Papyrus snickered, “YOU DID TELL HIM TO TAKE HIS TIME.”

Gaster snorted, “That is correct. I did, the crafty git.”

Papyrus tilted his head, “WHAT’S A-?”

Gaster glanced back at him, “Unpleasant person. Don’t worry, I say it with all the love in my soul. And don’t say that at school, it’s not a swear, but it’s not a nice word.” His father smirked, and Papyrus could see past it and his words. He saw what “love” Gaster was referring to, and it was not to the same caliber that he loved Papyrus, it was more, and much worse.

Papyrus didn’t fear his father, but he definitely had his apprehensions about him. Papyrus had no idea when or how this relationship between his only family had started, but all he knew was...that he’d seen his older brother kiss their father. Years ago, but it was not far enough away for Papyrus to forget anytime soon, especially when they practically flaunted in front of him.

Papyrus felt like the straight-man in a comedy, everything strange and weird happened around him all the time, and he saw and acknowledged it. But the other members of the show made him out to be an oblivious child that they had to protect, but in trying to cover up everything, they just made the chaos all the more noticeable.

Sometimes it would slip Papyrus’ mind, but then he'd see them looking at each other and the image of his older brother clicking his teeth to his father's would play in his mind on repeat. Papyrus sometimes thought of going to his father's house just to make sure, but he'd already seen the porn videos his friends were so obsessed with and had no desire to see his family doing something so vulgar. But then again, at least if he did see it, he'd have proof! Proof that he wasn't crazy or just misunderstanding something.

“Sans?”, Gaster's voice came from the kitchen. Papyrus got up from his seat and peered around the corner of the kitchen, his father was leaning up against the wall, talking into the phone.

“You only grabbed two boxes... There's like three more...yeah... Paps and I talked, you can come back.” Gaster turned his head to the wall and Papyrus could see a gathering of color on the father's face, clearly blushing. “Oh hush, get over here,” he said with a smirk before hanging up the phone. 

Gaster then noticed Papyrus looking at him and gave him a smile, “Your lazybones brother, you guessed right. He took a nap.”

“How stupid do you think I am?” Papyrus wanted to say, but didn't. He just nodded silently and made his way past Gaster to the fridge to grab a juice box.

-

Later that night Papyrus sat on the platform outside his and his brother’s room drawing a costume design in his notebook. He’d need to pick up sewing again, with no access to his good clothes.

He wasn’t sitting there for privacy or anything, in fact it was quite dark at the moment and he could barely see which color pencils he was picking up. He was sitting there, to look at his father. Sans was also there but had gone to bed ages ago.

Gaster stood by the window in a turtleneck and long slacks, all black, it was always all black with him. It looked good, fashionable, Papyrus saw it. He saw that and more, even how one could find him attractive, but he didn’t think so. He’d never be able to do what his brother did, if he’d even wanted to.

Papyrus knew that a lot of his hesitation to do anything about his family was due to how much information he seemed to be missing out on. Really, how could he trust either of them till he understood why they were together?

The young skeleton got an idea.

“DAD?” Papyrus called as he stood up. Gaster looked up to smile at him. “CAN YOU...TUCK ME IN?” even when he was acting to get results, it was embarrassing to say. He hadn’t needed to be tucked in for three years now.

Gaster nodded, “Of course, Pap. Anytime.” He began to make his way up the stairs, “Working on something?” He directed to the notebook in his son’s hands.

“Designs,” he said nonchalantly as he went into his room.

Papyrus jumped into bed, already wearing his pajamas and laid down. He set his notebook on his nightstand as his father knelt by his bed and began tucking the boy in, as if he had done it just the night before. In the meantime, he spoke softly to his son. “So I made a few calls today with a professional or two and I was thinking,” Gaster made sure what he was about to say wouldn’t come off as wary, “How would you like to meet with a therapist?”

Papyrus tilted his head, “LIKE, FOR CRAZY PEOPLE?”

Gaster shook his head, “For people who need someone to talk to, that’s all. Just while you’re out of school, and if you don’t like it, you can stop. But I really think it would help you.” He sat on the edge of Papyrus’ bed, “Look, I know...that what you said earlier is probably the tip of the iceberg that is your problems. And I’m not going to force you to tell me all of them, but I want to make sure you have someone to talk to, if not me or Sans.”

Papyrus nodded, “I...I CAN DO THAT. TRY TO.”

Gaster nodded with a relieved smile, “Great, then.” He patted the edge of the bed about to stand up before Papyrus grabbed his hand. His father looked at him, concerned. “Is there something wrong?”

The boy hesitated before shaking his head, “GOODNIGHT KISS?”

Gaster couldn’t help but smile, it had been ages since he’d been asked for a goodnight kiss from Papyrus, he’d grown so proud in his pre-teen years, it became a thing of the past. “Of course,” he agreed fully unaware of how closely he was being watched.

He kissed Papyrus’ forehead and asked if that sufficed, his son confirmed before closing his eyes and becoming very tired. Gaster left the room and closed the door behind him.

Like that, Papyrus thought that he’d confirmed his father’s innocence as well as he could and confirmed, fathers and sons don’t kiss on the lips. Now all he needed to do was somehow test his brother in the same way to figure out what course of action he should take next.

But regardless of the things that weighed on his mind, Papyrus was able to fall asleep with warm and safe thoughts floating through his subconscious. It really hadn’t occurred to him how much he’d really missed his father.