Chapter Text
Gaster was a scientist first and foremost. Everything he did or said was viewed from that perspective: the logical, ever analyzing perspective. Which is why he couldn’t for the life of him understand how an experiment with his soul had gone so... Wrong. It had been a fool’s experiment, and, despite being a royal scientist, it also wasn’t an entirely legal procedure. The dividing of a monster’s soul was dangerous, and medically inducing such a process could be entirely traumatic to a monster’s body. Gaster’s face was proof of this, but so was his two twin sons. Never in the history of monsters had there been twins before, it was scientifically impossible within the normal bounds of monster reproduction, but the soul Gaster created in his experiment was simply too weak. It had split before he could care for it, something that could have been avoided had he collaborated on the project with other scientists or even had an assistant, but despite the trauma it still formed into, not only one, but two monster children for each split part of the soul.
Gaster had bypassed most scrutiny of the illegal task because he had performed it on himself, but he had certainly gotten a tongue lashing from the entirely upset and worried King Asgore. (Of course over slices of butterscotch pie with his new baby boys in the king’s arms. The man was always a big softie, but especially for babies.)
He called them accidents, not really favoring one boy over the other despite one’s clear attempts at his attention. Many the parent had corrected him when he spoke of them that way, they would chuckle awkwardly before calling the boys miracle of science. Bah! Miracles his monster ass, they were scientific faults, even if they were good ones.
Of course that didn’t mean he cared for them less. He was their father, after all, and while he viewed their growth through life as a continuation of his experiment, he had found himself... Attached. Attached to each boys’ quirks. And whoo boy did they have a lot of them, and although they could grate on his nerves, he loved them. Sans was technically the older of the two, he had tried to come up with a physical form before his brother, even if it took a while for it to form properly. Papyrus was only younger by a few moments but definitely the healthier of the two, he grew and performed like a regular monster while often times Sans did not.
Gaster sighed contentedly, picking up his several notes over the boys’ lives. He supposed they were biological discoveries that deserved careful attention, at the time they were almost seven, practical babies for how long monsters could live, and their forms weren’t quite stable. They shared a room in their house in Snowdin, the place was practically a giant play pen for the still toddling skeletons. Everything had to be designed with their safety in mind, Gaster hadn’t had a home until the boys came along but he couldn’t have babies around the sharp objects and the dangerous chemicals present in his lab, even if Sans and Pap ended up at his lab for most of the day anyway.
The boys were certainly no strangers to the lab, not just the one at their house in Snowdin, but also the large, shared lab designed especially for the Royal Scientist and his team. They had a specific room at the lab, a sort of lobby with a large play area so that the scientists could keep an eye on their children while still working. Gaster’s boys practically owned it, keeping them at his work was cheaper than a babysitter(What? They charge extra for two!), but it also allowed him access to the equipment to check up on them as his continuous experiments. The thought reminded him that it was nearly noon and he needed to check up on the boys, so he stood to stretch. He decided to take his lunch break early, a lot of monsters went home for lunch but bringing in lunch for three monsters would be a hassle, so Gaster was known to be out of office around lunch. It wasn’t like the current projects were demanding his attention, the core had been up and running smoothly for years, so he mostly spent his time on understanding the properties of human and monster souls.
Gaster made long strides towards the lobby, finding his boys at opposite ends of the pen doing their own things. He frowned, they usually played together, but it seemed that Papyrus had grown bored with his brother’s napping. Papyrus’s speech was still a bit unclear, they were working on it, but he certainly was forming words and sentences by that point. He knew Sans could speak, but he usually responded in hands before spoken speech, he would speak if it got inconvenient to sign.
“DAD!” Papyrus dropped some toy he was playing with in order to rush over on his still stubby legs, grinning up at his dad. Gaster grinned back and picked him up,
“Hi, Pappy! It’s lunch time.” He spoke aloud, comfortable in doing so since it was just him and the boys in the room. He had been doing his best to speak aloud with them, more for the sake of his boys’ ability to learn to speak more than hands. It was also quite difficult to sign with a baby in each hand. The room had a fenced off area for younger kids, but it also happened to have all of the cushions and blankets, so it was there that he found Sans.
Gaster leaned over the pen’s fence to reach for the snoring Sans, unable to reach him, he sighed in annoyance. He had been surprised many times over by the six year old’s ability to sleep through practically anything, unfortunately that also meant when he did wake it was often with a start. Gaster let out a snort, both amused and slightly annoyed with the snoring child. Papyrus went on in his arms about how much Sans had slept that morning. At least he’ll take naps... Gaster thought, giving up on trying to reach for Sans and gently surrounded the child with his magic, picking him up and floating him over the pen’s fence, only to find he was still asleep peacefully. Whatever, Gaster huffed, letting the boy float idly as he stuffed a squirming Papyrus into his jacket.
“Hold still!” That got Papyrus to pause, but only to grin at him and go on about what he wanted for lunch. All that Gaster really got was something about pasta. Papyrus talked with wide gestures and Gaster wasn’t sure but it seemed like he often mixed hands and vocal speech together, so he was difficult to follow if you weren’t paying him total attention. Gaster finally slid the tiny arm into the jacket’s hole with a sigh of relief, then realizing the lack of shoes on both of the boys’ feet. The boys happened to be the same size at the moment so they liked to mix match their shoes. Unfortunately, that meant they were able to fling them good distances away and would take them off whenever the chance arose.
{Where are your shoes?} Gaster signed, watching Papyrus become intent on watching his hands as he did so. The boy just shrugged. With a deep sigh, he let the boy down, Sans still slowly turning in the air while asleep as he searched through the room. He eventually found a shoe on a window sill, part way across the room, and the others were in different areas around it. He chuckled,
“Aimed for the window today, huh?” Gaster walked back over to the three year old and slipped a wiggling foot into the shoe without too much trouble.
“WAIT!” Papyrus snatched another shoe from his father, one of his brother’s but thankfully for the opposite foot than the one he had a shoe on. Gaster raised an eyebrow, and Pap spoke, “I can do it myself!!” He began stuffing his foot into the shoe, Gaster let him wrestle with the ties as he turned back to the sleeping Sans still floating in his magic. Gaster decided to let him sleep for now. He set him on the floor with his magic before sliding Sans into a jacket identical to his brother’s. Gaster set the boy on the ground to slip the shoes, one blue and one orange, on his feet. When the second leg fell to the ground with a soft thud, Sans’s eye sockets blearily opened. A grin grew on his face as he sat up, reaching his hands out in a grabby motion toward his father.
“hi dad.” The voice was soft and tired, Gaster couldn’t help but smile and grabbed Sans into his arms before he turned back to help the, still struggling, Papyrus with his shoe.
Most days he took them home for lunch whenever the River Person was available, it was easier than packing lunches and lugging them to Hotland on the morning trip in. That particular day he planned on heading home to cook a nice little lunch for the family, probably some hot dogs cut up into little bites. They seemed to like that lunch best, especially when paired with macaroni and cheese. Gaster felt Sans’s head fall against his neck, he shook him lightly, annoyed by the idea of him hitching a ride to nap on the way home.
“Hey, don’t you go back to sleep.” He reached out the other hand for Papyrus, letting the boy walk on his own as they made their way out of the lab. Hotland was a bit stifling in their jackets, but it was difficult to maneuver the six year olds into jackets on a ferry as small as the River Person’s.
“Hello, would you like a ride?” The River Person spoke, an underlying boredom to the sound, but they put on a cheery customer voice.
{Yes, to Snowdin.} During the ride, he kept hand on each boy. It wouldn’t be the first time they fell off, but it was hard to deal with freezing, wet little kids. The ride was short and dull, he managed to keep Sans awake and as the boat pulled to a stop, he set him on the snowy ground. Papyrus followed in suit, Gaster keeping a hand out to make sure he doesn’t fall.
{Thank you.} Gaster signed to the River Person politely, and moved to follow his boys to the house. Without his hand to hold, they were holding each other’s and trudging through the snow. It was... adorable.
He walked behind them, the boys turned around periodically to make sure he was keeping up with the. The walk home probably took longer than it needed to because he didn’t just pick them up, but they had a little extra time that day. Gaster only stepped ahead of them to get the door, both boys padded in eagerly once it was open and kicked off their shoes. He kicked his own shoes off and followed them into the kitchen. Sans was helping Papyrus into his chair, but the chair was a bit tall for them. Gaster picked each boy up and set them in their respective chairs.
“How does hot dogs and mac and cheese sound?” He asked while getting out the pot.
“GOOD!” Papyrus’s response was enthusiastic, per usual.
“mm.” Sans laid his head down on the table in front of him. Gaster popped a hotdog for each of them in the microwave and put a pot of water on the stovetop to boil. It was then that he grabbed spill proof cups, filling them with water before setting one in front of Sans and one in front of Papyrus. He sat at the table himself to wait for the water to boil.
“SANS!” The one word Papyrus seemed to he able to say properly outside of ‘dad’ rang through the kitchen, and Sans raised his head in response.
“yeah?” He asked questioningly, truly a bit confused as to why he was being called out. Papyrus frowned,
“Don’t go back to sleep!” He demanded, causing his brother to laugh,
“ok.” He lifted his head up, sighing and stretching just a little in the chair.
“Do you want to play puzzles?!” Papyrus asked, clearly missing his brother when he had played earlier.
{Lunch first.} Gaster corrected, finishing up the macaroni and laying the food on plates.
“sure, bro.” Sans grinned at his brother, kicking his feet a bit. Their dad set ketchup on the table and served their plates out. Sans reached out and immediately grabbed the bottle of ketchup, flicked it open, and poured it over his plate. With a sigh, Gaster took the bottle from him, otherwise he’d just drink the stuff, and Papyrus made a face at his brother before digging in to eat. Despite being the sleepier child, Sans was not lazy when it came to eating. Papyrus ate like he was going to shoot up a foot, both were probably about to hit a growth spurt, Gaster thought with a slight frown. They grow up so fast. Lunch was pretty quiet, but fast.
They had a little extra time at the house before needing to go back, so after dumping their paper plates in the trash the two boys ran off to play. Papyrus dove for the crayons, but not before Sans took a few colors to use himself. Puzzles were commonly played between the two, but they were in need of a new book since all that was left was crosswords. With annoyance, Pap pushed the book to Sans who began evaluating the puzzles with a keen eye, crayon in hand. They worked side by side on separate projects, Sans on the crossword and Papyrus doodling a cute picture of their family.
“Brother?” The question cut through the comfortable silence and concentration. Sans didn’t even look up to respond,
“yes?”
“Do you have the green crayon?”
“... no.” The crayon was clearly in Sans’s hand, he was using it.
“... Brother! Don’t lie!”
“i don’t know what you’re talking about.” He continued using the crayon in plain sight.
“Saaans! I can SEE it!”
“oh? really? you should use it then.”
“OK!” Papyrus snatched it from his brother’s unsuspecting fingers. “I think I will!” Sans frowned and reached for it, only to have his hand smacked away by Papyrus.
“hey! i wasn’t done using that!!” Sans reached further for it, sliding on top of the other six year old to try and reach it. Papyrus gripped the crayon in his hands and sat up. Sans rolled off him in the process and sat back up to reach, pulling on his brother’s closed fists. “pap!!! no!!!”
“PAPYRUS, YES!” He turned and yanked his arms back, pulling Sans back onto him, shoving both of them back to the floor.
“stop! give it back!”
“NO. IT IS MINE NOW.” This was just the beginning of the wrestling battle that ensued, despite it still being mostly light hearted it was certainly a six year old all out brawl.
Gaster stood in the doorway, hands covered in dish washing gloves as he watched the boys fight. Just as he was about to stop them, in fear one of the low hp kids would get hurt, but instead their souls popped from their magical bodies, as if entering a real fight. Afraid they would actually hurt each other in a battle, Gaster began walking towards them.
“That’s enou-” The souls, instead of becoming battle ready, glowed obnoxiously bright, a line clearly showing where each soul had split from each other, but also from Gaster. Slowly, they merged into each other, overlapping and nearly ‘clicking’ into place as they completely overlapped. They seemed liked puzzle pieces, but Gaster didn’t have time to consider it with the flash of light his boys were gone, and in their place was a single six year old.
“What the frick?” The skeleton boy, who somehow resembled both of Gaster’s missing children promptly covered his mouth at the curse. He guiltily looked down, “Oops, sorry Dad.”
“... Sans...? Papyrus...?” Gaster uttered in total confusion to his... Son? He guessed? The boy frowned and shook his head, as if confused with his own existence. With wobbling arms, the newly formed skeleton pushed himself up to stand, nearly falling in the process. He wore a mix of the clothes from his sons and his features reflected each boy as well. Gaster held put a hand for him to stabilize on so he, hopefully, wouldn’t fall over. Who knew how stable this form was?
“Comic Papyrus, Dad!” He grinned, an expression that was so reminiscent of Sans’s. Gaster sat on the couch, staring at his son unwaveringly.
{Is this not weird to you?} The six year old gave him a blank look.
“... No? Should it be?” Comic Papyrus frowned deeply. The gears were moving in Gaster’s head, he could faintly remember whispers of a fusion magic back when the monsters had fought the humans, But that’s a lost magic...! With new energy, Gaster stood suddenly and picked Comic Papyrus up into his arms. The skeleton was sturdier than Sans or Papyrus, but Gaster was used to holding a boy in each arm, so it wasn’t any trouble.
The River Person gave him and Comic Papyrus a strange look, but didn’t ask. Gaster practically ran into the lab when they stopped, frightening a few scientists just leaving. He passed through the Magic Biology halls, the section manager pausing to talk to him,
“Wow, Gaster, who’s the kid?” The doctor could clearly tell he was trying to rush to his lab, so she kept pace as he signed to her.
{Long story thi-}
“Hi! I’m Comic Papyrus.” He grinned proudly at the doc, Gaster sighing as her expression morphed into a mix of surprise and confusion. Who named some random kid after their kids?
{He’s Sans and Papyrus. They... Fused.} Gaster signed, unsure of his own hands as they did so. The doctor stopped walking and Gaster paused to converse with her.
“But... That’s a lost magic...”
{Exactly. Shouldn’t even be possible for monsters who haven’t even developed magic yet.} With that, he walked into his lab, the largest room of the building, and shut the door behind him with finality. He set Comic Papyrus on a bed that resembled a hospital bed, one that Sans and Papyrus were familiar with from regular check ups. The boy kicked his legs as he watched his dad rush back and forth through the lab, gathering the machinery and tech he needed. For what, exactly, Comic Papyrus wasn’t sure.
Gaster didn’t run any...rough, tests. No extraction of magic or anything. It might cause instability in the fusion, and he didn’t want to risk a de-fusion before he could test anything. It was plain on Comic Papyrus’s face that he knew what was going on and he looked conflicted between nervousness and trying to hold a stoic expression. He squirmed a bit as Gaster prepared the first test, recognizing the machine, he felt a bit relieved, still slightly uncomfortable.
The test was to get a reading on magic use, it was commonly used to analyze a monster’s physical-magical form, but in this scenario it could be used for more than that. The machine whirred to life, and almost in a heat-detector but for magic manner it focused in on Comic Papyrus’s soul. There was a dense, unstable concentration of magic along the seam of where Papyrus and Sans’s souls first split. The machine allowed Gaster to see the soul, and he stared at the image for a while before having the machine take a picture and print it out. He turned it off and pushed it away, not wanting to use up unnecessary bed space. He sat back in his desk chair, looking over the printed image in his hands.
Comic Papyrus sat on the patient table, internally arguing about how to feel. It came out as little murmurs under his breath, conversing back and forth,
“there’s something wrong.”
“No! Dad would let us know if there was a problem.”
“we aren’t supposed to be like this, this is bad!” Comic Papyrus’s voice rose suddenly, causing Gaster to turn to him suddenly in confusion, watching as the boy practically shivered, nearly in tears. His soul popped from his chest, souls wrenching apart and Comic Papyrus disappearing before Sans and Papyrus reformed.
“Oh, welcome back, boys.” Gaster spoke, voice betraying a bit of disappointment. Whatever magic they had accidentally triggered could be crucial to a victory in the potential war after Asgore broke the barrier. The two ignored the comment, frowning at the other and continuing the argument.
“Dad would tell us if we did something bad!!” Papyrus spoke, trying to encourage his brother and cool him off more than anything.
“not if he couldn’t do anything about it.” Sans pouted and crossed his arms. Papyrus just walked over and hugged him. Gaster crouched down to their level, hugging them both as well.
“stop.” Sans wiggled in the grip, “stooop. let me be mad.” The hug didn’t cease, and eventually Sans was hugging back.
“You didn’t do anything wrong.” Gaster pulled back to look both of them in the face, “That was a kind of magic that hasn’t been around for a very long time.” The boys positively glowed,
“SO WE’RE REALLY COOL?” Papyrus looked ecstatic, Gaster chuckled.
{Of course, but not just because of your magic.} He paused, standing up. {Well, I still have some work to do. Go play, be nice.} Gaster resigned himself to the fact that the fusion was gone for now, not that he wouldn’t push for them to try the magic again later.
“OK! C’mon let’s go-” a yawn interrupted Papyrus mid sentence, very unlike him, “play, Sans!”
“alright, bro.” The two slipped out the door, leaving Gaster to consider fusion magic.