Archive of Our Own

Old Man: Flight lznds at NRT Friday at 6

Old Man: Can’t wait to see you!!

Old Man: One fo the new interns is a bi engineer and I think you’dd really like her!!

Old Man: *bio but I mean I cah ask her about that too??

Senku scowled down at his phone before tossing it onto the counter with a huff.

“Uh oh,” Gen sing-songed from his place on the couch, somehow having already managed to get horizontal despite only arriving twenty minutes earlier. “Did Chrome-chan eak-bray something again?”

“Probably,” Senku snorted, turning his attention back to the gyudon simmering on the stove. “The Old Man’s back on Friday and he’s already started with the dating bullshit.”

Gen hummed, staying carefully silent and smiling to himself when Senku continued.

“I just don’t get why he cares so much about whether or not I’m fucking, isn’t that something parents try to keep their kids from doing?”

Letting out a surprised laugh, Gen sat up, “I highly doubt that’s what Bya-chan’s thought process here is,”

“Asking me for grandkids is just asking about how much unprotected sex I’m having with extra steps.”

Gen shook his head fondly - while he could understand Senku’s frustration he, like most of Senku’s friends, found Byakuya to be a constant delight.

Warm, friendly, ridiculously kind. He was the sort of man who not only knew the convenience store cashier’s name, but the name of each of their kids and which schools they went to. The sort that remembered birthdays, treated his son’s friends as his own children, picked up a souvenir at every airport and city he visited, and never missed his weekly call with Senku regardless of what was going on.

He also had exactly one recurring concern when it came to his twenty-four year old son - that Senku would manage to science himself into accidental lifelong bachelorhood.

The fear wasn’t unfounded - Senku worked strange hours, often forgot to eat and avoided sleeping unless someone made him, and reacted to people flirting with him the way most reacted to solicitors. He’d never once shown the slightest interest in anyone - not Kohaku who half the university assumed he was dating in secret, not Luna even after she cornered him in a biology lab to confess her feelings, and not any of the random researchers or grad students that expressed an interest in him over the years.

“He just wants you to be appy-hay and to know that someone is taking care of you while he’s away.”

“I am happy,” Senku grumbled, rubbing the bridge of his nose. “And according to everyone else, you take care of me.”

“I do make sure you eat your veggies, yes.”

Gen ducked the balled up sock Senku threw at him with a laugh. Based on the bright shade of pink, it was one of Gen’s, though he’d be hard pressed to recall when he’d left it there or how it had ended up in Senku's kitchen.

While Gen had his own place across town in some ritzy high rise, he saw it maybe twice a week at best, many of his things having made their way to Senku’s over time. He had a spare toothbrush set in a little cup next to the vanity - the vanity that was practically overflowing with his array of creams and lotions and fancy bath essentials with Senku’s horrid two-in-one shampoo left to languish on the shower shelf. An entire cabinet in the kitchen had been dedicated to a variety of teas and the couch he rested on was laden with a veritable mountain of throw blankets - none of which Senku had knowingly purchased.

Somewhere along the line, “coming over to hang out after work” had become “existing in Senku’s apartment by default”. Neither of them had questioned it, it was a routine that worked for them.

“I just don’t want to spend a whole week dodging the topic,” Senku finally huffed. “Last time he was here he kept showing me pictures of random women and offered to text them for me. As if what was stopping me from dating was being too afraid to text them.”

“Well, have you considered lying?”

“About what?”

“Tell him you’re already seeing someone, get him off your ack-bay.”

“You’ve been watching too many of those shitty K-dramas again, haven’t you?”

Gen gasped in mock offense.

“There is no way the Old Man would fall for that. He’d be snooping through everything and talking to everyone to find out who it is. Probably corner me in the bathroom and force me to call them to introduce himself.”

“That’s why you actually have someone pretend to date you,” Gen countered.

“…like an escort?”

Gen stared at him. “...I mean… that’s ertianly-cay an option but I was thinking I could do it.”

“...huh?”

“Think about it,” Gen held up his hand and started counting off his fingers. “I already spend most of my time here, Bya-chan already knows me and knows that we’re good friends, and I’m a skilled actor. Pretending to be your boyfriend would be easy.”

Senku seemed to be actually considering it so Gen pressed on before the scientist could poke holes in the idea.

“It’ll be a lot easier to sell with someone who already knows you and Bya-chan well. Someone else might slip up and start talking about how omantic-ray you are and we both know he’d call bullshit on that. And,” he held up another finger, “he loves me, so he won’t be disappointed in your choice of partner and try to set you up with someone else anyway.”

"What happens when he starts asking Taiju and Yuzuriha about it? Neither of them can lie for shit."

"We tell him we haven't told anyone else yet so as not to ruin group dynamics in case it doesn't work out," Gen replied easily, watching as Senku's eyes narrowed in consideration. He could tell by the purse of his lips he was close to being convince and gave one last push. "Which will make it easier when, after he goes back to the US, we wait a few weeks, tell him we decided we worked better as friends, and it gets him off your back about dating for a while.”

Senku was quiet for a long moment. Gen watched the gears turning behind his sharp red eyes with all the measured detachment of a man who definitely wasn’t laying his own heart on the line.

“...it’s ten billion percent unethical.”

“Since when has that ever stopped you?”

“...touché.”

—

“Senkuuuuuu!!” 

Senku winced at how his neighbors would react to the shout, bracing himself as Byakuya enveloped him in a hug nearly as bone-crushing as Taiju’s.

“You’ve gotten thinner! I thought you were eating better?”

Senku grunted, patting Byakuya on the back a few times before gently pushing him away. “I am and no I haven’t - I weighed myself yesterday and I’m exactly the same as when you left.”

Byakuya made an over the top skeptical sound before his eyes shifted over his shoulder and lit up.

“Gen! What a wonderful surprise!”

Pushing past Senku, Byakuya approached with arms wide and Gen laughed, allowing himself to be pulled into a much less aggressive embrace. “Well, when Senku-chan said my favorite astronaut was coming for a visit, how could I iss-may it?”

Senku snorted, pulling Byakuya’s suitcases out of the way to shut the front door, barely biting back a smile at how easily the two fell into conversation about Byakuya’s trip and the flight attendant he’d befriended on the way.

“-and when I woke up there were two cans slid into the little pocket in front of me!”

“Oh-hooo, you charmer! Lillian-chan better watch out,”

“Nah, it’d take at least ten ginger ales to make me even consider it. Fifteen, even.”

“Meanwhile Gen would probably sell me for a can of coke and a twizzler.”

Gen gasped, looking at Senku with wide eyes, “As if I’d settle for less than three twizzlers.”

Byakuya laughed loud enough that Senku was certain at least one of his neighbors was regretting renewing their lease.

Less than an hour later, Byakuya had declared that no one was allowed to cook and had marched all three of them to the little ramen shop he and Senku always visited on his trips home. They didn't even need to order, the owner immediately ushering them to a table and calling out to the staff. Senku and Gen watched as dishes piled up around them, their ramen along with a spread of appetizers and side dishes covering most of the table, sipping their drinks while the two older men chatted about the owner's daughter and cooed over photos of his latest grandkids.

Senku grimaced at the topic, shoving noodles into his mouth in hopes it would keep Byakuya from asking questions.

It didn’t work.

“So…” Byakuya picked up his chopsticks as the owner gave him one last clap on the shoulder and headed back to the kitchen area. “Did you think about any of the girls I mentioned? They all seemed pretty interested in talking to you after I showed them your picture.”

Gen caught Senku’s eye, giving a small, almost imperceptible nod.

Senku took a slow breath, “Actually, about that,”

Byakuya leaned forward, smiling expectantly.

“I didn’t want to tell you over the phone but I’m, uh…” he stuck a pinky in his ear, shifting awkwardly in his seat, “I’m already seeing someone.”

Byakuya’s jaw fell, “What?! Since when?!”

“About six months.”

“Six months?!”

Senku shrugged, “Wanted to make sure it was working out before I told you,”

Byakuya gaped, looking at Senku in disbelief. After a moment he collected himself, shaking his head, “Well, where is she? I obviously need to meet the girl who got you to settle down!”

“It’s not a girl and you’ve already met him.”

Senku shoved a mouthful of noodles into his mouth, nodding his head vaguely in Gen’s direction and the mentalist barely stopped his eyes from rolling, giving Byakuya a shy wave. 

“Surprise?” He gave a small laugh. “We haven’t really told anyone in case it didn’t work out.”

Byakuya stared and Senku awkwardly slurped at his ramen as the silence stretched just long enough to become uncomfortable.

“...You’re dating Senku?”

Gen smiled, giving a small shrug, “That is generally the term for it, yes.”

Another beat.

“YES!”

The shout rattled the glasses on the table and a few other diners looked in their direction curiously as Byakuya practically vibrated in his seat, reaching across to grab both of Gen’s hands.

“I’m so glad it’s you!” he beamed, eyes tearing up happily. “You already know how impossible he is!”

“Hey!”

Neither looked in Senku’s direction as Gen stared at his and Byakuya’s joined hands in surprise, eventually letting out a hesitant laugh. “I wouldn’t put it at-thay way…”

“I should’ve realized when he started hanging his clothes up and wearing things other than graphic tees. You’ve always been one of the only people that can get him out of his comfort zone- and the way he talks about you!”

Gen blinked, looking at Senku just as the scientist coughed, holding a hand up to his face as he set his drink aside and attempted to clear his airways. 

“You’re not upset about no grandkids?” he wheezed, the clumsy attempt to change the subject obvious.

“You can adopt,” Byakuya replied easily. “If you want kids, of course.” His attention turned back to Gen, “Tell me everything! How’d it happen? What was your first date? Is he treating you right?”

Senku was suddenly glad that Gen had insisted they come up with a back story and had drilled him on it that morning.

“I treat him fine.”

Byakuya didn’t even look in his direction when he shushed him.

“Senku-chan is a wonderful boyfriend,” Gen said easily, “considering who aised-ray him, how could he not be?”

Byakuya beamed, listening raptly.

Gen glanced at Senku out of the corner of his eye. “We’ve never been able to agree on what our first date was, but as usual, Senku-chan was the brave one between us.”

“Senku asked you out?”

“Hmmm, more like pointed out we were spending nearly all of our free time together doing things that couples usually do,” Gen tilted his head and smiled wryly, pulling his hands free, “it was all ather-ray romantic.”

Senku snorted and Gen bumped his shoulder against him just enough to push him sideways, reaching over to snag a piece of karaagi Senku had plated for himself. He easily dodged Senku’s passive attempt to stop him, quickly stealing a second before the plate was moved just out of reach.

Starting to fill his own plate, Gen continued. “He said we were pretty much dating already, might as well do it for real. How could I ossibly-pay turn down such a heartfelt proposal?”

Byakuya threw his head back, laughing loudly. “I knew it.”

“You knew jack shit,” Senku deadpanned, absently moving his plate back into place as Gen dropped three pieces of kabocha tempura onto it.

“I suspected,” Byakuya wagged a finger. “Every time I called, Gen was either there or had just left or was coming over and every time I asked what you were up to it was always Gen and I are this and Gen’s making me do that- no matter what we talked about it always came back to him.”

Senku grumbled, “He’s around a lot.”

“Hmm, someone has to make sure he’s fed and watered regularly,” Gen teased, adding another piece of tempura to the scientist’s plate as if to prove his point. “It’s a hard job, but I’m up for the task.” 

Byakuya laughed again, picking up his chopsticks to begin filling his own plate. “So long as he knows you’re way too good for him, Gen,”

Gen opened his mouth to make another teasing remark only to be surprised when Senku spoke first.

“Trust me, I know.” 

It was said so casually, Gen was momentarily speechless. Senku didn’t seem to notice the reaction, shoving a gyoza into his mouth before pushing away from the table, something about needing the bathroom muffled by a mouthful of dumpling.

The moment he was out of earshot, Byakuya’s chopsticks came to a halt.

“I think I owe you an apology,”

Gen blinked, a spoonful of ramen pausing halfway to his mouth, “…for?”

“For never seeing it,” 

A creeping dread began to spread through Gen but he kept his expression carefully neutral and his mouth shut.

Byakuya rubbed the back of his neck awkwardly, laughing. “I spent years trying to introduce him to other people, asked you to help even!”

Images flashed through Gen’s mind - Byakuya forwarding photos of smiling women, asking if he thought Senku would like them, if Gen would be able to convince Senku to at least go on one date. Conversations ending with Byakuya sighing dramatically about his impossible son, Gen smiling and gently redirecting things somewhere else.

“I can’t imagine how difficult that must’ve been for you.” 

Gen waved his hand, hoping his laugh didn’t sound as fake to Byakuya as it did to him. “No orries-way, you couldn’t have known-“

“But that’s the thing, it’s so obvious now! The way you look at him… I always thought it was because you’re an attentive friend, but that was only half of it.”

Gen swallowed, praying that there was a long line for the restroom and he could pivot the conversation before Senku returned.

“…was it, now?”

Byakuya nodded without a trace of hesitation, “Definitely.” His expression softened into something gentler than his exuberant delight from a few minutes earlier, warm in a way that Gen found surprisingly comforting. “When someone loves another person it changes the way they pay attention… you always noticed things about Senku no one else did.”

“Ah, I am a mentalist after all, so…”

“Oh don’t sell yourself short,” Byakuya wagged a finger. “No one else knows Senku as well as you do, not even me. And I raised that little demon.” Byakuya shook his head fondly, smile wry. “And you still said you’d date him,”

Gen let out a tiny, helpless laugh, “Yes, well… even with all his quirks, Senku-chan is… rather extraordinary. It was bound to happen.”

That, at least, wasn’t a lie. Gen hadn’t woken up one day hopelessly in love with his best friend out of nowhere, it had accumulated in microscopic layers. Teasing remarks and coffee made exactly how Senku liked it, waiting with him through late night experiments and being the first person Senku called when something impossible finally worked, conversations that stretched for hours until it was far too late for Gen to even consider heading home.

Somewhere between all of it…

“One day I just… looked up,” Gen found himself saying, almost to himself, “and realized there wasn’t anywhere else I’d rather be.”

Byakuya smiled, eyes looking a little misty. “And look at you now.”

Before Gen could reply, they heard footsteps approaching, looking up to see Senku returning from the bathroom.

“What’s the look for, Old Man?”

“Just talking about how cute you two are,”

Senku’s nose wrinkled as he slid back into his seat, “Gross, can you not?”

–

Dinner stretched far longer than necessary, the conversation easy as empty plates piled up around them. Byakuya filled them in on NASA gossip and silly stories about Dr. Xeno and Stanley, Gen responded with his own stories about work and their friend group, and Senku occasionally supplied corrections when either of them exaggerated too much.

Despite the little remarks and the teases about their “relationship”, Senku was surprised to find that it felt exactly like every other time the three of them had been together.

Familiar, easy, comfortable.

And once the plates were cleared and the bill paid - heavily discounted, Senku couldn’t help but notice - Byakuya insisted on taking the long way home because “I’ve been trapped on a plane for fourteen hours, let an old man stretch his legs.”

The walk became an excuse for Byakuya to comment on every tiny change since his last visit - a bakery that used to be a book store, new benches installed by the conbini, a vending machine that used to dispense coffee now full of sports drinks.

Gen hung back with Senku while Byakuya perused the options, continuing to chatter mostly to himself.

“...This is going too well,” Senku muttered.

“You sound disappointed.”

“I’m suspicious.”

Gen tilted his head, “Do you think he’s onto us?”

“Nah, he can’t act for shit,” Senku replied easily. “I just thought we’d have to, I dunno… work a little harder?”

“Hm?”

“It barely feels like we’re doing anything and he just bought it.”

Smirking, Gen nudged his shoulder, “Is this your way of asking me to start calling you babe and hanging all over you?”

The look on Senku’s face must’ve shown exactly how he felt about that and Gen laughed.

“Senku-chan, despite what some of our friends may have you elieve-bay, most couples don’t spend every second making heart eyes at each other or being sickeningly lovey-dovey. They just… exist together.”

Senku considered it for a moment, watching as Byakuya pulled what appeared to be his fourth drink from the machine.

“Though, now that it’s on the table, being able to call you honey bunny without you being able to do anything about it is rather empting-tay…”

“I will duct tape your mouth shut.”

Byakuya returned, arms laden with an assortment of beverages, before Gen could reply, but he couldn’t help but notice the small smile on Senku’s face.

–

By the time they made it back to Senku’s apartment, it was nearly midnight.

Byakuya stretched dramatically once they were inside, groaning like every joint in his body had simultaneously decided to mutiny. “I’m officially too old for international travel.”

“You’ve said that since you were thirty.”

“And I keep proving myself right.”

Gen laughed, and without thinking reached out to catch Senku’s hoodie before the scientist unceremoniously dropped it to the floor, hanging it up with a practiced ease. “I suppose this is where I leave you, gentlemen.”

“Nonsense! It’s way too late for you to head home,” Byakuya insisted firmly.

“Ah, but with you in the guest room-”

Byakuya snorted, “I’m a little too old to have been born yesterday, Gen, you don’t need to pretend you and my son don’t sleep together when I’m not here.”

Gen made a tiny squeaking noise, ears going brilliantly red.

Smirking the smirk of meddling fathers everywhere, Byakuya started towards the guest room, clapping Senku’s shoulder as he passed.

“Jet lag’ll probably have me out like a light, but at least try and remember your old man’s next door if you get up to anything.”

Senku sputtered, turning to Gen when the door to the guest room clicked shut. “I am going to pretend he did not just imply what I think he implied.”

Gen had both hands over his face, a muffled noise escaping from between his fingers. “He said it so casually.”

“Ugh, don’t remind me…”

There was a beat and Gen peered through the gaps between his fingers, catching Senku’s eye, and suddenly the two were dissolving into helpless laughter.

Senku pulled himself together first, shaking his head as Gen continued to giggle and making his way down the hall to his bedroom.

It should’ve been strange just how normal it felt, the two sharing a space - but between hotel rooms, overnight trains, friends’ couches, and camping tents, sleeping in the same room let alone the same bed barely registered for them anymore.

Gen disappeared into the bathroom to do his nightly skincare routine, returning fresh faced and in an old t-shirt of Senku’s he’d appropriated as pajamas months ago.

Senku changed into sweatpants and plugged Gen’s charger into the outlet on the side of the bed he knew he preferred, piling an extra pillow for good measure.

The overhead light was turned off and they settled into place, the dim glow of Gen’s phone screen painting soft blue across the headboard as Senku laid back, sighing deeply as he sank into the mattress.

For a long moment, neither of them spoke, the quiet of the apartment only interrupted by the sound of the AC and the occasional tap of Gen’s thumb against his phone.

“...He’s happy,” Senku finally said.

Gen’s scrolling paused, “He is.”

“I figured he’d be okay with me dating a guy,” Senku frowned at the ceiling thoughtfully. “Didn’t expect him to react like we’d cured cancer.”

Laughing softly, Gen resumed his scrolling, “Your father is a simple man, Senku-chan, he likes people that make you happy.”

“...I guess.”

Gen shook his head, reaching over to plug his phone into the charger Senku had already set out for him. “Ah, my hero,” he teased. “As always, your romantic gestures leave me utterly eathless-bray.”

Senku snorted into his pillow. “Don’t get used to it, I just got sick of you stealing mine all the time.”

“I prefer to think of it as sharing.”

“You prefer to think wrong.”

Gen laughed, setting his phone down onto the nightstand and laying back. 

The room fell back into silence - not an awkward, tense one, or the kind that begged to be filled. Just… quiet.

Senku stared at the ceiling, one hand tucked under his pillow behind his head, the other resting on the blanket between them, listening to the things he’d stopped consciously noticing ages ago.

The rustle of Gen adjusting the blankets, the soft surruss of his hair against the pillowcase, the quiet little hum he always made when he was almost asleep.

Usually things like that would’ve driven him nuts, had him on edge with his teeth grit and unable to sleep, but for some reason it just felt… normal. Familiar enough that when Gen shifted again and the mattress dipped beneath the movement, Senku automatically moved in counterpoint without a thought.

He’d spent years cultivating an environment with as few unaccounted for variables as possible - predictable routines, predictable noises, predictable results.

Somewhere along that line, Gen had apparently become one of those constants.

– 

The next morning, Senku woke to the smell of coffee.

He blinked blearily, head turning to find Gen still asleep next to him, face half-buried in his pile of pillows. He’d shifted closer during the night, a wide swath of mattress left behind him and one hand loosely resting on Senku’s chest, breaths slow and even and hair a complete disaster.

He looked… comfortable.

Like he belonged there.

Senku didn't linger on the thought, slipping quietly out of bed. He found Byakuya in the kitchen scrolling through his phone with a simple spread of rice, tamagoyaki, and miso soup in front of him. 

“Morning, I made breakfast if you’re hungry.”

Grunting, Senku walked past him to the coffee machine, automatically reaching up to Gen’s tea cabinet and grabbing the one he knew the mentalist preferred in the morning. 

Byakuya hid his smile behind his coffee. “You two are good together.”

Senku groaned, rolling his eyes. “We are not-”

He stopped himself.

“...right.”

Byakuya’s smile widened and Senku ignored him by busying himself with measuring tea leaves he didn’t actually need to look at. He already knew exactly how much to use, how long to steep it, how much honey to add if Gen had been talking a lot the day before or had an appearance or film shoot scheduled for the day.

His hands moved on autopilot and he was viscerally aware of how Byakuya’s eyes followed his every move.

“Don’t be so smug, Old Man.”

“I’m not smug, I’m delighted. It’s different.” Byakuya took a sip of his coffee before setting his mug down on the table. “I never thought I’d get to see you being so… domestic.”

“Domestic,” Senku repeated flatly and Byakuya only looked more amused.

“I always thought you’d need to find someone who could keep up with you, who could understand the wild way your brain works and wouldn’t get frustrated when you dove head first into a project for days - but I really should’ve been looking for someone who could get you to slow down a little.”

Senku opened his mouth to argue, but before he could he was interrupted by the sleepy shuffle of familiar feet.

Despite his obvious grogginess, Gen’s face was freshly washed and there was a spot of toothpaste at the corner of his mouth that he’d missed. His hair was still a bit disheveled, wearing the same t-shirt from the night before, but the moment he saw breakfast laid out his eyes lit up.

“Oh, Bya-chan, I’ve issed-may you!”

“I am wonderful, aren’t I?”

“The est-bay,” Gen agreed, taking a seat at the table. He barely shifted when Senku put down his mug in front of him, not at all phased by the other man’s reach, arm automatically moving to leave space for him to take the adjacent empty seat.

The motion was so smooth Senku almost didn’t notice.

He did notice the way Gen immediately stole a piece of tamagoyaki from his plate before even touching his own food, though.

Also the way Senku made no move to stop him.

How Gen hummed approvingly after one sip of tea, clearly pleased by the results.

And, most annoyingly, the way Byakuya was noticing all the same things.

–

The rest of the visit passed almost suspiciously smoothly, the story selling without either of them really trying.

Mostly because there wasn’t much to sell.

And yet, Senku still found himself… noticing things.

Not because anything between them had changed, but because despite their little scheme nothing had. 

Gen still let himself into the apartment after work without knocking and Senku still remembered to add extra sichuan pepper to his portion of mapotofu.

Gen picked up Senku’s phone to reply to texts for him and Senku rolled his eyes when Gen nagged him about how many energy drinks he'd consumed in a day. 

How they moved around each other in the kitchen with a practiced ease, how Gen reminded him of paperwork he needed to bring to work, how Senku didn’t question the clothes that definitely weren’t his in the laundry. 

Now that he was looking for it, he saw it everywhere - tiny little things, a lifetime of microscopic data that somehow added up to something enormous that he’d never considered before.

The night before Byakuya was set to leave found them in the living room, some b-tier horror movie playing on the TV and the leftovers of their takeout on the table waiting to be put away.

Byakuya had claimed the arm chair, leaving Senku and Gen to take their usual places on the sofa. Gen had checked out of the movie rather quickly, scrolling through social media while Senku did some work on his laptop.

He felt the cushion dip with Gen’s movement, shifting without a thought to make space for him to tuck his foot under Senku’s leg, the other sprawling over his lap behind his computer.

Senku’s hand dropped to find Gen’s shin without a thought, attention only pulled from the article in front of him by the sound of a stifled laugh. He looked over to find Gen smiling down at his screen, nose crinkled with amusement and lower lip caught between his teeth, fingers moving quickly.

A moment later he felt his phone vibrate in his pocket, only vaguely wondering what ridiculous meme Gen had sent him as he found himself suddenly viscerally aware of the position they were in.

He felt Gen’s toes flex under his thigh, the warmth of his calf seeping through the fabric of his jeans, the familiar scent of his ridiculously overpriced shampoo, the way his screen reflected in his eyes as he continued scrolling. For a moment Senku wondered just how much battery life Gen’s phone had, only for the familiar “battery save” alert to pop up across the top of the screen and for Gen to swipe it away without a thought. 

If anyone walked in and saw them, he was sure they’d assume they were dating. It was why the last week had gone so smoothly, why he hadn’t needed to put much thought into the act.

Except, it wasn’t an act. This was a position they ended up in regularly, regardless of if there was an audience or not.

Senku had always just written it off as them being good friends, but in that moment, his brain decided it apparently hated him and he found himself imagining Chrome sitting in Gen’s place instead.

Immediately he felt his lip curl in distaste.

He cycled through a few more - Kohaku, Taiju, Ryusui - every single one of them felt wrong. Not because he disliked any of them or was opposed to touching them, but the space that Gen occupied was-

Senku stopped, realizing that was the issue. There was a space - but it was a specific one that belonged to Gen.

His eyes shifted back to his laptop when he recognized he was staring, only for another thought to occur.

Instead of someone else where Gen was, what if someone else was where Senku was?

Gen sitting on someone else’s couch, wearing one of their sweatshirts and dusted with the crumbs of their snacks he had stolen. Someone else who knew exactly how Gen took his tea and how long his nighttime routine took.

Gen showing someone else the ridiculous things he found online, laughing with them the way he did with Senku, falling asleep beside them, kissing-

Something in Senku’s chest twisted unpleasantly, sharp and almost visceral in its rejection of the notion.

Gen belonged here.

Gen belonged-

It was stupid, ridiculous even, and yet the thought refused to go away.

Byakuya left the next morning in a chaotic blur of last minute packing, a ridiculous amount of hugs despite Senku’s increasingly irritated protests, and Byakuya making Gen promise to call him if Senku “did anything stupid”.

“I’d be calling you multiple times a day,” Gen teased, allowing yet another hug from the other man.

“Especially stupid, then,” Byakuya clarified, pulling back with his hands still on Gen’s shoulders. “Though I can’t say I’d mind you calling multiple times a day.”

Gen had laughed and Senku rolled his eyes, “As if you aren’t the one calling all the time, Old Man,”

“Ah, but now I have someone to call who will actually answer the phone and be truthful about how you’ve been,” Byakuya beamed.

Senku wasn’t surprised when Byakuya pulled him into one last hug, patting his father on the back.

He was surprised when Byakuya whispered in his ear, though. 

“You take care of him, alright?”

“Aren’t you supposed to say that to him?”

“I’m saying it to you.”

Byakuya pulled back just far enough to look at him, smile softening and all the teasing fading from his expression.

“Take care of him, Senku.”

For once, Senku didn’t have a sarcastic answer ready. His eyes flicked across the room to where Gen was checking his phone for the status of Byakuya’s car, feeling something coiling in his chest that he couldn't quite identify when he realized Gen was wearing his sweatshirt again.

Gen looked up at exactly the wrong moment, catching Senku staring.

“Hm?”

“Nothing.”

Gen narrowed his eyes suspiciously, looking to Byakuya for an answer, only for him to squeeze Senku’s shoulder and step away.

“You know,” he said conversationally, pulling up the handle of his suitcase, “I think you two might actually be good for each other.”

“Yeah, yeah…”

“I mean it.”

Senku rolled his eyes with a huff, “I know.”

Byakuya studied him for another long moment, seemingly deciding whether to say something else.

Whatever he was thinking about, the beep of Gen’s phone signalling the arrival of his car seemed to sway him into swallowing it.

“Good,” he nodded, stepping into the hallway. “Bye, boys, I’ll text when I land.”

Senku watched him go, the door closing behind him and leaving Senku with a strange weight settling somewhere behind his ribs.

–

And just like that the performance should have been over, except it wasn’t.

The plan had always been for them to continue the act for a little while following Byakuya’s visit. Let him enjoy the idea for a few weeks and get used to it before staging a mutual break up that was nobody’s fault and, ideally, discouraged him from setting Senku up with anyone else for a while.

It was simple, barely needing any real thought.

Except Senku thought about it anyway.

He thought about it when Gen arrived with grocery bags, letting himself in and wandering into the kitchen to stock the fridge while proudly explaining that he’d known Senku would have forgotten to do it himself and showing off the ridiculous flavor of candy he’d bought.

He thought about it when Gen stole half his lunch and then acted offended when Senku called him out on it.

He thought about it when Gen fell asleep on the couch halfway through some terrible reality show wearing Senku's sweatpants and Senku automatically lowered the volume and dimmed the lights for him, but didn’t turn it off.

He thought about it when he found himself picking up a bottle of overpriced face wash when he was out, not only recognizing the brand but remembering that Gen had said he was running low on it.

Mostly he thought about it because none of it felt different from before.

They hadn’t actually started acting like a couple, they’d simply started calling what they were already doing “dating”.

And now that Senku was aware of it, he couldn’t stop thinking about it.

Six weeks passed, and neither mentioned the break up.

At first, Senku blamed it on both of them being busy, then because Byakuya had just called and it seemed harsh to drop the news on him out of the blue, then because there just wasn’t a good time to bring it up. 

Eventually, though, he stopped coming up with excuses. The truth was that neither of them wanted to bring it up, that it was easier to just keep going. That everything just felt so effortless that sometimes Senku forgot there was even supposed to be an expiration date to begin with.

Which was probably why the words came seemingly out of nowhere. 

“We still haven’t done it.”

Gen, who was finishing up with the dishes, froze for a moment, but from the angle Senku was standing he couldn’t see his face.

“Ah, the break up?”

The words were said lightly, as though Gen was commenting about something forgotten at the store or the weather, but Senku knew Gen well enough to hear the hollowness and his eyes narrowed.

“Yeah.”

Gen turned off the faucet, grabbing a dish towel to dry his hands as he turned to face Senku with a smile. Bright and easy, the sort he put on when cameras were rolling that gave no hint to how he was actually feeling.

“Probably should’ve done that already,” he said with a laugh. “Though it would’ve been rather ean-may to to immediately drop that as soon as Bya-chan was back in the States. ‘Hello, remember that thing you were so happy about? Never mind!’ - though I suppose it’d be you that would have to have that conversation…”

Senku didn’t reply.

“And then there was that grant deadline you were working on and that three-day shoot I had- we’ve been so usy-bay I’m surprised we’ve even had time to sleep let alone talk about this-“

“Gen.”

“-though it was probably for the best that we waited. If we’d done it too quickly it would’ve looked uspicious-say. Needed to set it up as a genuine relationship that just didn’t work out instead of a fabrication-“

“Gen.”

“-but we do need to get our stories straight in case anyone asks. Maybe something like we mutually decided to end things because neither of us wanted to force something that wasn’t working? That’s probably the most mature and-“

Senku reached forward and put his hand over Gen’s, stopping him mid-sentence.

“You’re doing it again,” he said simply. “That thing where you keep talking until you don’t have to answer.”

Gen’s smile twitched. “I don’t know what you’re alking-tay about.”

“Bullshit.”

There was a beat of silence and Gen looked away with a small sigh. “What do you want me to say? You want to break up.”

It wasn’t a question and Senku’s brow knit up.

“What? I thought you wanted to,” he made a frustrated sound. “This whole thing was your idea from the start.”

“Because you wanted your dad off your back!”

“Yeah, six weeks ago. And then we didn’t break up.”

“Yes, well-”

“I don’t want to.”

Gen’s words caught in a jumble of consonants, eyes wide at the quiet admission.

“I thought about it. About what would happen… after, y’know? You going back to your apartment, me doing whatever I was doing, telling the Old Man it didn’t work out. Everything goes back to normal.”

Gen hesitated for a moment. “Sounds reasonable.”

“It sounds fucking terrible.”

Senku looked down at the floor, jaw working as though he was trying to arrange thoughts that refused to fit neatly into words.

“I kept thinking that once it was over...” he rubbed the back of his neck, visibly frustrated. “You started staying here because it was convenient. And then you started keeping clothes and brought all your bathroom shit and buying groceries and stealing my food and somehow I know what tea you want without having to ask even though you have like forty of them.”

Gen smiled faintly despite himself, “Forty-three.”

Senku made an annoyed noise, “When you’re not here I notice.”

That wiped the smile from Gen’s face, but Senku continued before he could interrupt.

“That it’s too quiet and there’s only one cup in the sink and no one’s forcing me to go to bed by turning off the lights and threatening to throw my laptop off the balcony.”

Senku looked away and Gen’s breath caught in his throat. “...That’s just you being used to me being around.”

“That’s what I thought, too,” Senku admitted, looking back up, his expression softening ever so slightly. “Until I realized I don’t want to get unused to you.”

Gen’s heart stuttered in his chest, beating so fast he was sure Senku could hear it.

“That’s… we’re…” he cleared his throat. “We’re good friends...”

“Maybe,” Senku leaned closer, eyebrow raised. “But I don’t think friends are supposed to make me feel like I’d rather rip out my own teeth than picture you doing any of this with anyone else.”

Gen went very still, eyes widening in surprise. Senku looked almost irritated by his own confession but continued regardless.

“I tried to imagine you with someone else - in their apartment, wearing their clothes…” his jaw clenched, “didn’t like it.”

“Senku-chan…”

“And I don’t want anyone else doing it with me, either. I only want you.”

There were a dozen ways Gen could have responded and usually would have - a sarcastic quip, a teasing remark, some clever way to deflect away from the serious topic suited to his carefully curated persona.

Instead, the only thing he could muster up was tiny, helpless, “…oh.”

Senku snorted, incredulous, “Really? I say all that cringy shit and that’s all I get?”

Gen flushed pink, shoving the dish towel he was still holding into Senku’s chest, “Shut up,”

“Make me.”

Senku easily pushed the towel aside, leaning in before Gen could react beyond a comical widening of his eyes.

The kiss wasn’t nearly as awkward as it should’ve been, instead being almost unfairly familiar - just like everything else between them. Gen’s hands caught the front of Senku’s shirt, fingers curling into the fabric as one of Senku’s rose to cup his jaw, warm and steady. For a moment, their minds went completely, blissfully blank.

And when they finally pulled apart, all Gen could do was stare. “You issed-kay me.”

“Yup.”

“…you actually issed-kay me. On purpose.”

Senku rolled his eyes, “Starting to regret it.”

Gen used the grip he still had on his shirt to pull him back down, the second kiss less careful and much less surprised. It lingered, carrying the same strange sense of familiarity - as if it was something they’d been doing all along.

“Regretting it less,” Senku murmured when they pulled apart again, earning a helpless laugh against his lips.

He was halfway to kissing Gen again when his phone buzzed on the counter.

Then again. Then a third time.

Senku glared at it with the sort of murderous irritation he reserved for failed experiments or when Gen beat him at Mario Party at the last minute after being in last place for the entire game.

“Could be important,”

“It’s probably the Old Man.”

The phone buzzed again and Senku’s scowl deepened.

“Definitely the Old Man.”

When he made no move to grab his phone, Gen rolled his eyes, reaching past him to pick it up.

As expected, there were several text notifications lighting up the screen.

Old Man: I just rememberde I don’t have z my pictures of you two since you started datingb

Old Man: send me one

“Told you it wasn’t important,” Senku huffed, tips of his ears going pink as he snatched the phone out of Gen’s hands before he could do something like snap a photo of the two of them in their current state.

Gen's hair was a little mussed from where Senku's hand had found it, lips wet and slightly kiss-swollen - Senku could only imagine what he looked like and how Byakuya would react if he could see it.

He'd never live it down.

Old Man: I wanna shiw everyone my future son in law

"Future son-in-law, huh?" Gen mused, smile soft and fond as he peered at the screen.

Senku quickly swiped the message away with a flick of his thumb, heat creeping up the back of his neck. "Don't encourage him."

Gen's smile only widened, eyebrow raising as the phone vibrated again.

Old Man: tell Gen I said hi!

Old Man: you better be spoiling him!!

“Hmm, I could be more spoiled,” Gen suggested, laughing when Senku tossed the phone across the room to the sofa.

Senku grunted, shifting his legs apart to make space to pull Gen back in. "If you were any more spoiled, you'd be ten billion percent unbearable."

Gen grinned, letting himself be maneuvered, arms looping loosely around Senku's neck as the other man's settled almost unconsciously on his waist, "Unbearable, huh? It's a wonder you've put up with someone so unbearable for so ong-lay, let alone consented to date them."

Senku smirked, moving in for another kiss, "Yeah, well, we were pretty much dating already... might as well do it for real."

Gen laughed at the echo of their fake story, heart fluttering as he leaned in to meet him halfway without hesitation.

"Might as well."