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Honestly, having Asagiri Gen as a roommate turned out better than Senku had expected.
He hadn’t really wanted a roommate, but scientific equipment cost money, and with Byakuya living in America with his new girlfriend, Lillian Weinberg (and no longer having that no-limits NASA credit card), Senku had to find a new source of income while working on his double PhD in astrophysics and aeronautical engineering. So renting out his dad’s old room to a friend of a friend (well, Ryusui was more an acquaintance of Nikki’s, who was friends with Kohaku more than him) it was.
At first, things were...tense. Gen kept odd hours (which was fine, Senku did too) and that meant they didn’t talk to each other much, and so were both a bit unsure of each other. Senku likened it to them both being stray raccoons that patronized the same dumpster, just at different times.
And then Gen started bringing people back to the apartment. Which was technically also fine, since Senku hadn’t put any restrictions on overnight guests, but they weren’t always there at night.
Senku would never forget coming back home after his last lecture of the day ended at three, only to hear the porn-star worthy moans of a young woman coming from Gen’s room.
After standing in the genkan in shock for far too long, Senku made haste back to the campus library and put in an order for noise canceling headphones (with overnight shipping). He’d never actually noticed how thin the walls were in the apartment. Byakuya had only complained about the damage from occasional explosions, not the noise.
Things were...fine, after that. Senku noticed Gen put in extra effort cleaning the communal spaces now that he had guests over, which was nice. Gen also apparently liked to cook, and while he wasn’t amazing at it, it was definitely edible, and much cheaper than takeout, while also being healthier than the amount of cup noodle Senku was used to eating. Aside from the loudness of some of his guests, Gen was a fairly considerate roommate.
So the noise canceling headphones were a small price to pay.
Until suddenly they weren’t. They’d been roommates for fifteen months and Senku didn’t know when things had changed, but they did. Maybe when he met some of Gen’s actual friends, as opposed to his ‘guests’. (It was somehow unsurprising that Gen knew Ryusui, but Ukyou, a submarine sonar officer, was a bit weird.) Maybe when Gen had met his friends, and promptly charmed them all, even his former mechanical engineering teacher, Professor Kaseki. Maybe when Senku and Gen started eating together at the tiny kitchen table on a regular-ish basis, instead of in their respective rooms. Maybe when they started talking over those meals about deeper subjects than groceries and laundry.
Maybe when they started hanging out when they were both free and watching animal documentaries and cheesy sci-fi, which apparently they both liked for letting their ever-active minds wind down.
Senku didn’t even notice anything changing until the night he heard Gen moaning through the walls and instead of automatically reaching for his headphones while vaguely wondering how he hadn’t noticed someone ringing the bell, a visceral sense of...disgust and anger pooled in his belly.
After spending another far-too-long moment in shock (still hearing Gen’s moans), Senku slammed on his headphones and questioned himself repeatedly. Disgust? Anger? What in the love of Tesla was he feeling those for? Gen had every right to have guests over, and why was it only bothering him now?
A week of stewing in his own emotions and surreptitiously watching Gen every time they crossed paths, and Senku had a hypothesis.
He was jealous. Not of Gen for having a (albeit slowly) revolving door of fuck buddies (Senku hadn’t met many of them, but some were definitely repeats), but of whoever had made Gen moan like that.
Because, and this was more shocking than that series of electricity experiments he’d run when he was eleven (which had singed his hair and caused it to look like a dandelion for three weeks), he wanted to be the one making Gen moan like that.
Which led him to his most ridiculous experiment to date, but then, what could one expect from an aeronautical engineer and astrophysicist who’d decided to do a complete 180 and conduct a sociological study?
Senku was choosing to call it that in order to maintain what little bit of sanity he had left. One did not come to terms with suddenly developing romantic and sexual feelings for one’s roommate all at once, especially when the one in question had never even given his sexual or romantic orientation any thought.
That was, in hindsight, ten billion percent a mistake. Senku would have to make an effort to keep abreast of his own emotions going forward, so he wouldn’t be ambushed by them again.
But mostly because, if his experiment worked, Gen would be the recipient of a lot of his feelings, and he deserved for Senku to not make him do all the emotional work regarding their relationship.
If it worked.
***
Step one was a success at least. Senku knew Gen was on Tindr; he’d seen enough notifications on the other man’s phone. Making a profile of his own was easy, as was using photos of Chrome’s girlfriend Ruri (whom Gen had never met, seeing as she had stayed in hers and Chrome’s hometown to run the family shrine instead of attending college) after he’d run them through an AI program to digitally alter her to be male.
‘He’ didn’t really look like Senku, but the result was a light-haired male of the right age, and Senku figured he should stick as close to the truth as possible if he wanted this to work out how he wanted.
Step two was also a success. Find Gen’s profile and match with it. Step three was where everything could break down (the first time), since it was dependent on if Gen messaged him back.
It was a nerve-wracking three days for that, even as Senku knew Gen’s class schedule and that he had an important paper due. But eventually, Gen messaged back.
Trying to be as honest as possible (but as blunt as Senku usually was) while also trying not to make it obvious that Senku was Senku was...honestly Senku felt like he was walking an emotional tightrope over shark-infested waters. He had sudden sympathy for every one of his classmates he’d rolled his eyes at, because they’d claimed to just have no clue where to start with math, science or anything else, because it just didn’t make sense to them.
To Senku, math and science and physics had always made sense, like the fundamental rules of the universe that they were. Purposely trying to cultivate a friendship with someone he was already friends with without letting them know it was him? Yeah, that ten billion percent made no sense, and he regretted his lack of empathy in the past, because it was coming back to bite him now.
But finally, after six weeks of frustration, nerves and occasionally elation, the time had come for step four.
The date. Gen didn’t always go on dates with his Tindr hookups, but he also didn’t generally talk to them for so long beforehand either. Senku had made it clear that Kuriro, despite using Tindr instead of OKCupid or Match.com, was looking for a relationship, long-term if possible. Gen had seemed open to the idea, at least, and they’d texted a lot before Senku had finally offered that they meet.
Which led directly to step five, more honesty.
***
Kuriro: I have something to confess.
Gen: Oh?
Kuriro: The pics in my profile are digitally altered.
Gen: Haha, I think we all try to show our best sides on here, and maybe a little more. ;)
Kuriro: Yeah, but…I mean that I purposely made sure they didn’t look like me.
Senku held his breath as he waited for those three dots on the screen to finalize into words. Then he gasped for air because he couldn’t hold his breath longer than twenty-two seconds and it took Gen forty-eight to reply.
Gen: Alright, I’m listening.
Kuriro: The thing is, I was pretty sure you, people, would recognize me and I wanted to be able to connect without all the...baggage.
Which was 95% honest, if vague, and leaving out the most important part - that he was only worried about Gen recognizing him.
Another thirty-three seconds of waiting for those three dots.
Gen: I get it. I’m not famous famous but sometimes fan can be...overwhelming.
They’d talked about Gen’s mentalist career, so ‘Kuriro’ knew almost as much about it as Senku.
Kuriro: So are we okay?
Gen: Are you going to send me an updated picture before our date?
Senku took a deep breath and responded with the final step of his plan.
Kuriro: I was thinking I would wear something to let you know it’s me. So you could make up your mind then.
Only eighteen seconds of waiting this time.
Gen: What would you be wearing? ;)
Finally Senku started to relax. If Gen was using emojis again, then things were probably fine.
Kuriro: A purple shirt and white coat.
A labcoat to be precise. Senku wanted to make sure Gen knew it was still him.
Gen: I’ll be there~!
***
Which is how Senku got to this point: waiting at a table in the back corner of his favorite hole-in-the-wall Ramen shop, leg jiggling like he’d slammed three Red Bulls on an empty stomach, a bouquet of nightshade blossoms (sentimental claptrap, but he had one chance on a new first impression) laying on the table in front of him.
“Senku-chan...?”
The lost-sounding voice of his roommate and crush brought Senku out of his spiral of worries. His red eyes met Gen’s stormy gray-blue ones, which were completely unreadable, as Senku had never seen them in the entire seventeen months of their acquaintance. Gen was a master of only showing what he wanted people to see, and right now Senku couldn’t get a read on anything about how Gen was feeling.
Which was to be expected, since Gen was an expert in that field.
“Hi, Gen,” Senku said, voice cracking on the other man’s name. He cleared his throat. “I’m glad you didn’t leave when you saw me.”
“I almost did,” Gen admitted after eleven seconds of silence. “But my curiosity was roused.”
Senku nodded; he could work with that. “I’m sorry for the deception,” he started, figuring he should get the apology out of the way first. “If you sit down, I can explain."
Gen looked him over, and Senku tried to actually emote honesty or sincerity, or whatever he could. He probably failed, but over the course of their acquaintance Gen had developed the ability to read his intent anyway. When Gen’s eyes landed on the flowers, Senku saw the first emotion in the other man’s eyes: interest, or maybe the aforementioned curiosity?
“These are for you,” Senku said, rather unnecessarily, as he handed them over.
Gen stared at the flowers for a long moment before dropping down rather ungracefully into the seat across from him. “Alright,” he agreed, pulling the bouquet towards himself. “Talk.”
So Senku did. About how he’d had some difficulty realize his feelings, and then spent ten days holed up in old man Kaseki’s spare room, occasionally helping him at this forge (he’d lied to Gen and said he was visiting Byakuya so his roommate wouldn’t worry about his absence) alternately cursing the illogicality of emotions and romance, and trying to figure out what he should do with them. It would probably have been better if Senku had glossed over exactly how he’d realized his feelings, but the scientist was nothing if not honest, generally, and considering the long con he’d committed against Gen, the truth was the least the mentalist deserved.
Gen’s face barely even flickered as Senku mentioned that penultimate moment, which Senku tried not to be unnerved by. “And you decided to make a fake Tindr profile because...?” his roommate questioned leadingly. His face was no longer so unreadable, his shoulders not as stiff. He was even, occasionally, stroking the petals of the flowers.
Senku bit his lip and scratched his ear. “I basically underwent a complete paradigm shift in regards to my feelings for you, and I wasn’t sure, really, how to talk to you about it,” he admitted. “But I thought that the biggest barrier to, uh, anything happening between us was how you saw me. I mean, I went from thinking of you as basically a stray cat I occasionally fed-”
Gen choked at that, eyes bright, cheeks pink. “What?” he barked out, amusement overtaking his features.
Senku’s ears burned, even as he was thankful the other man wasn’t offended. He continued, “-to a friendly acquaintance, to an actual friend, and that’s what we were, to me, for nearly a year. I figured it was normal for people to have more than three close friends, so that’s what we were, and having you all of a sudden not being in that conveniently labeled box-”
Gen snorted again, sending him a dry look, and Senku couldn’t blame him. Most of the conveniently labeled boxes in his home lab were stuff he didn’t use very often - which meant almost nothing was labeled.
But Senku persevered. “Well, anyway, I thought maybe you had me in a convenient box too, and needed a chance to see me differently. So I tried this.” He gestured at his phone, which was on the table in front of him.
Gen’s owl-eyed look made it clear that he thought Senku had lost at least half his prodigious mind to contrive this plot, which, well, fair. “So you decided to catfish me on Tindr?”
Senku squirmed. “It wasn’t really catfishing…” Which was a weak excuse; it totally was, if not for the most common reason.
Letting out a long sigh, Gen slumped back into his seat. “So Kuriro?” he asked. At Senku’s nod, he frowned. “How did you come up with that name, anyway?”
Shrugging, Senku said, “I’m not very creative, but I figured Kusen was too obvious. And a shadow is a reflection of a thing, so…”
“So how much of you did Kuriro reflect?” Gen’s eyebrow arched as he pinned him with those searching eyes.
As always, Senku felt as seen as a microbe on a microscope slide whenever Gen looked at him like that. “As much as I could get away with without giving away who I really was.”
Now Senku was back to counting seconds. Gen’s look wasn’t blank, but it was still as indiscernible to Senku as Greek philosophy. It was only when the table shook slightly that he realized his leg had started jiggling again. Senku flushed at Gen’s amused look. Emotions were so illogical, they couldn’t be controlled at all, and he hated that.
It was kind of amazing how they could make him feel, though. At least when what he was feeling wasn’t guilt. Or anxiety. Or worry. Or...
Maybe they weren’t amazing.
But then, after forty-seven seconds, Gen’s lips turned up in the slightest of smiles. “You really are emotionally constipated, aren’t you?”
Senku’s nose wrinkled. It was true, but why did the mentalist have to put it like that? “Emotional fiber doesn’t exist, or else I could take it with my morning coffee,” he shot back petulantly.
“But would you?” was the arch response.
Swallowing his nerves, Senku admitted, “For you, anything.”
The way Gen’s entire being softened at that admission was basically a miracle on par with the discovery of the Higgs-Boson; Senku was now ten billion percent certain he at least had a chance.
Cheeks an adorable pink, Gen cleared his throat. “All right. Okay. Say I forgive you for the deception…”
Senku leaned forward, attentive.
Gen’s eyes were finally clear, his feelings no longer hidden. “I’m sure once my mind has stopped whirling like your centrifuge, this will actually all make sense - for Senku values of emotional incompetence.” Senku thought ‘emotionally incompetent’ was a bit much, but he still couldn’t help but be pleased that Gen referenced his centrifuge; it meant Gen paid attention to him.
Sweet Tesla, he was so gone for the other man. “But for the moment…” Gen continued, hesitant, “where do we go from here?”
“Where do you want to go?” The ball was in Gen’s court, after all. “I mean, I’ve said what I want..." Wait, did he? Explicitly? “A relationship. Or at least a date,” Senku clarified, smiling bashfully.
Gen nibbled on his lower lip as he nodded, gazing unseeing out the window. Then his eyes snapped back to Senku and he gave a firm, decisive nod. “A date. We’re already here, so…”
Definitely more than a chance.
“You said this was your favorite restaurant?” Gen’s voice was skeptical as he gazed around the neon and chrome interior of Ramen Noodle Lab.
To be fair, it had looked less upscale (more normal) before the (extremely unneeded, in his opinion) remodeling the previous year. The food was still the same, though. “It is,” Senku confirmed. “My old man introduced me to it when I was young and we come here whenever he’s in town.”
Senku recognized that gleam in Gen’s eyes; he got it whenever Senku actually shared some personal tidbit with him. The mentalist had often complained that he was ‘so arsimonious-pay with your backstory, dear’. The scientist had initially thought it was a friend thing, but maybe it was more…?
“Oh, lore?” came the expected response. Senku had always thought memes were an interesting bit of pop culture, but couldn’t understand why anyone would devote so much time to them. Then Gen showed up and after only a few months he’d found it cute.
Senku really had been oblivious to his own feelings to an egregious extent. “Lore,” he agreed.
Snorting softly, Gen pulled a menu toward him. “Then what’s good here?”
Finally feeling the tension of the few weeks start to leave him, Senku let himself think over what he’d eaten there. “The karaage is only average, and the takoyaki portions are too small, but other than that, anything here is good,” he reported. “I like the tonkatsu best.”
Gen’s smile was knowing and fond. “Why am I not surprised?” he teased. It was one of the few dishes Senku knew how to reliably cook, and the one he made most often.
Senku shrugged, unbothered. “I know what I like.”
Those simple words won him another blush. Gen stared at the menu, clearly avoiding Senku’s search gaze. “And you like me?” he asked, voice shaky yet intent.
Soft red eyes looked at the mentalist, who was for once not hiding his feelings even if he was hiding his face. “Yeah, I do.”
The tiny little smile Gen aimed his way at that honest statement made Senku believe that he had more than a possibility of a chance.
It looked like his first sociology experiment was, hopefully, going to be a success.