Chapter Text
The problems start when Gen finds out Ukyo is apparently a very good singer.
Or rather, that’s when Senku recognizes he might have an issue.
The mentalist and Ukyo have developed what appears to Senku to be a very close friendship, although he can’t fully understand why. Gen had seemed very intimidated by Ukyo when he was describing him to Senku in the lead up to the war with Tsukasa’s empire. He’d described Ukyo as one of their major chokepoints. Ukyo had seemed terrifying at the time, grown larger and more alarming in Gen’s telling.
But that seems to be in the past now. They work together exceptionally well - Ukyo teaches the children math, and Gen will often pitch in and help. In the evenings, when one of them isn’t on cooking or clean-up duty, they often sit by each other, laughing hard. They’ve also been working on a project.
It makes Senku pause a little bit, when he notices. He’s not sure why, really - it just seems like the sort of thing Gen should have mentioned to him. Instead, Senku sees him in the middle of it.
Senku had made Gen a set of playing cards some time ago - a gift, though he never explicitly called it that. He’d needed something to do, some idle project to test the paper he’d been refining, the ink batches, and the newest version of his lacquer sealant. Designing the face cards had given him an excuse to test carving miniature stamps for consistency. He’d written scientific theories on them - the uncertainty principle, the theory of evolution. He tells himself it’s to remind Gen that some things are factual, unlike everything the mentalist does.
He still doesn’t know when Gen’s birthday is. But the idea of giving something back, after being gifted the observatory, had nagged at him until he caved and made the deck. Gen had blinked at it like it was a trick hand grenade, then grinned in a way that made Senku’s stomach feel oddly warm and knotted at the same time.
“A fraud magician needs his tools of the trade,” Senku had said, more defensively than he meant to.
Gen’s smile had stretched into a delighted, conspiratorial smirk. “A scientist enabling a fraud magician? Be still, my grifter heart.”
Senku had rolled his eyes while Gen cackled.
Privately, later, he’d replayed that smile more than once. He wasn’t sure why. In the modern day, Gen had seemed so pointlessly frivolous to him, someone cashing in on fame and bad books. He’d expected that Gen was one of those people who would have a public meltdown one day, and then spend years doing the rounds on morning shows to talk about whatever charity he’d gotten into that would inevitably be revealed to be a tax fraud.
None of that applies to the Gen he knows now. The Gen he knows now is one who is sharp and funny and brilliant, someone who held out his hand and offered to jump into hell alongside Senku. But it’s also not a reason he should be thinking about the fact that the mentalist has very nice smile lines by his eyes.
But he now sometimes sees Ukyo bent over, helping Gen design what looks like a set of tarot cards. It’s not the cards themselves that bother him. Tarot is bunk, pure pseudoscience. He’s said as much to Gen multiple times, and Gen never argues, just winks and says, “Not everything has to be real to work.”
But still. The tarot cards are one of Gen’s things - much like psychology, like magic, like botany. He claims not to believe in them, but he still likes them. “It’s like taking a personality test without having to do the work, and prettier art,” Gen once said when Senku had accused him of secretly believing in crystals. Ukyo, nearby at the time, had laughed, and Gen had grinned at him.
Senku finds himself wondering, at odd moments, Why didn’t Gen ask me to help with them?
He could’ve made proper cardstock, could’ve tested plant-based pigments, could’ve engineered a fixative to keep the images from smearing in humidity. Could’ve contributed something tangible.
He’s not sure why he’s thinking this. He’s immensely busy. The boat is a massive undertaking. They’re still integrating with the Empire of Might, especially in the aftermath of Hyoga’s attempted mutiny and Tsukasa’s cold sleep. He’s barely really has the time to eat; he doesn’t really have the spare time to justify working on an artistic project that has no survival merit.
But he still finds himself wishing he was asked.
He spends a lot of time with Gen - the fraud magician is basically his second-in-command. He’d gotten used to looking over and seeing Gen there, waiting to hear what was next. Gen’s the first person he looks for when he needs to discuss strategy or iron out details of a plan. But with the way their population has swelled and the scope of their tasks have changed, Senku somehow has even less time lately to think about anything that isn’t work.
It’s more challenging that he had thought it would be - being a leader and bringing back the science of the old world.
He’s walking by, heading back to the lab after having just eaten, when he hears Gen say, “I do miss music. Having Lilian’s song is lovely, of course, but I do sometimes wish we had more to listen to. I wasn’t often allowed to go to concerts myself - the perils of being famous - but I did have an extensive collection of CDs.”
There’s a pause. Senku glances over without meaning to. Gen has his chin in his hand, gazing up at the sky like it might hum back a melody. The fading light outlines his profile in gold, casting long shadows that make him look older, gentler.
“Did you play anything?” Ukyo asks.
“Alas, no,” Gen sighs dramatically. “I had a dream of learning the piano, but I can’t even read sheet music. I once tried to teach myself, but between shows, appearances, and dodging the occasional stalker - well, I never got far. I did sing in the shower often enough to annoy my neighbors, though.”
Ukyo chuckles warmly. “I get that. I sang a lot growing up. Music was very important to my family. The day of the petrification, I was supposed to go meet one of my cousins for a karaoke night.”
Gen’s eyes brighten. “Dear Ukyo, are you telling me you’ve been hiding a musical talent all this time?”
Ukyo smiles, almost shy but clearly pleased. “Guess so. I’m out of practice, but I can still carry a tune.”
Gen leans forward, absolutely delighted. “We are absolutely having a performance night. You can sing, I can do magic. I’ll make a stage, I’ll get dear Yuzuriha to make you something indecent for you to wear - oh, the possibilities!”
Senku realizes he’s slowed to half his normal pace, standing just far enough away to hear them without being part of it. Ukyo’s laughing and trying to deny it. Gen’s getting into the description of the costume he’s going to get for Ukyo, getting really into the weeds of it. Senku forces himself to keep walking, though their voices follow him, threaded through with laughter.
It’s nothing, he tells himself. Just a conversation about music. Just another trivial, unnecessary thing Gen happens to share with Ukyo instead of him. He’s too busy to care, much too busy to waste neurons on anything except keeping civilization moving forward.
And yet the thought nags him, sharp as grit under his skin: Ukyo has the time to sit and talk with Gen. I don’t. He laughs with him. I don’t.
Senku presses his lips into a thin line and walks faster toward the lab. His mind insists it doesn’t matter. His chest, traitorous thing, burns with the opposite.
—
Gen doesn't let the fact that Ukyo can apparently sing drop. Senku can’t really explain why, but every time the topic comes up, he finds himself tensing up. He tells himself it’s because he assumes that, much like Byakuya, these two probably have terrible taste.
Byakuya loved pop hits, absolutely indecipherable jazz, American 80s power ballads, and anything with bagpipes. He couldn’t sing - never once in his life did he manage to hit a note properly - but he tried. He loved serenading Senku while making dinner - his favorite song was Total Eclipse of the Heart. Senku would slap his hands over his ears and escape to his room while his dad laughed uproariously.
Music, to Senku, had always been one of those strange, unquantifiable phenomena that everyone else seemed to understand intuitively. People often compared math and music - Byakuya had said jazz was “math in motion” - but music felt too wild, too unconstrained to fit neatly into equations. Math was the structure beneath the universe; music was something messier, more primal. It was like everyone else was fluent in a language that he could only catch fragments of. When he did listen to it, he often picked instrumentals or LoFi - something easy to study to.
The passion others feel from music feels perplexing. He wonders if it's how he feels when he understands a physics equation for the first time.
It comes up again while Ukyo and Gen are supposed to be looking through the landscape aerial photos to find the Sagara oil fields. Senku is sketching out a plan for the speedboat he’ll make if they can ever find the fields. The other two have been staring at the pictures for hours, but for the last forty minutes their focus has clearly frayed. The light is changing, afternoon gold pooling over the paper and catching on dust motes drifting lazily in the air.
Senku can’t entirely blame them for being distracted, though he wishes they’d try harder to stay on task.
“So what kind of songs do you like to sing?” Gen asks suddenly, leaning back on his hands.
Ukyo smiles sheepishly. “I prefer to sing in Swedish and English to Japanese,” he says. “I like how they sound for music.”
“Why the fuck do you speak Swedish?” Senku asks without looking up. “I didn’t even think Swedes spoke Swedish. I thought they just made furniture and ate pickled fish or something.”
Ukyo blinks at him, amused. “My dad is Swedish,” he says, like it’s the most obvious thing in the world. “Didn’t you ever wonder about my coloring? I don’t exactly look fully Japanese.”
Senku opens his mouth, then closes it again. He had noticed - of course he had - but he doesn’t usually store data like that unless it has scientific relevance. Still, now that Ukyo mentions it, the lighter hair, the arctic blue eyes - they track.
“I’m the last person who should be commenting on someone’s looks,” Senku says drily after a moment. He doesn’t often think much of his looks, but he’s not so socially unaware as to miss that he looks unusual. A parent of a classmate in elementary school once accused Senku of being a child of the devil due to the redness of the eyes. More than one person has told him his hair reminds them of a leek.
Gen, predictably, jumps in with a smile that practically sparkles. “Your hair is very distinctive, dear Senku, but then again, so is all of dear Ukyo! You can shoot arrows like a mythical hero, scale trees like a cat, you’re an excellent strategist - what else you have hidden up your sleeve, hmm?”
Ukyo gives a self-deprecating shrug, but there’s a flicker of pride in his eyes. “Apparently, singing.”
Senku stiffens slightly. The word is innocuous, but the way Gen’s face lights up isn’t.
“It’s just so delightful,” he says. “Please, dear Ukyo, you must sing for me soon. It’s so rude of you to tease me. How dare you hide this talent!”
Ukyo chuckles. “It’s not like I was professional in any sense. I just sang a lot with my mom when I was little. She used to play guitar. It was our thing.”
Gen makes a soft, delighted noise. “That's so sweet. I love that.”
“I didn’t know you played guitar,” Senku says, sharper than he means to.
Ukyo raises an eyebrow. “I don’t. My mom did.”
“Hmm,” Senku mutters, turning back to his notes and pretending to be absorbed. His pen moves, but he’s not really writing.
“And then I kept up singing when I was in the SDF,” Ukyo says. “It’s really hard to have time to yourself and destress when you live in a sub with a bunch of guys with a macho chip on their shoulder. They always thought I was a bit too soft. Every shore leave, first thing I would do would be go find a karaoke bar and sing until I was hoarse.”
“Incredible,” Gen breathes, looking very entertained. “And this allows me the opportunity to ask, where’d the archery come from? Seems like a strange hobby for someone who spent a lot of time underwater.”
Ukyo laughs, slightly uncomfortably, and rubs at the back of his head like he’s embarrassed. “Ah. Uh, well, it’s also from my mom. She represented Japan in the Olympics for archery in 2004.”
Senku looks up despite himself. “Seriously?”
Ukyo nods. “Yeah. She won bronze. I was little, but I remember the medal. She also taught classes. I’ve been doing archery since I was six, I think.”
Gen clutches at his heart theatrically. “A polyglot with a secret voice and a genetically Olympian backstory? Be still my heart.”
Senku rolls his eyes, but the corners of his mouth twitch upward, then drop again almost immediately when he sees Gen still grinning at Ukyo, eyes shining with unguarded admiration.
Something prickles in his chest, low and hot and annoyingly personal.
It feels like that time when Taiju gave up trying to explain why he was so excited about Lilian's new album and went to find Yuzuriha, like there's these things people just realize they can't trust Senku to understand, so they find someone else who will.
“Right,” Senku mutters. “So, karaoke prodigy, Olympic DNA, fluent in Swedish and proficient in English. Anything you don’t do, Ukyo?”
Ukyo blinks, caught off guard. “Um. I can’t cook?”
Gen laughs. “A tragic flaw! Thank goodness. Otherwise, I might have to hate you out of sheer inadequacy, dear Ukyo.”
Senku lets the laughter wash over him and forces himself to focus on his page, even as the conversation swirls around him. He feels tense. He’s not sure why.
“We should have some kind of variety show,” Gen says musingly. “It’d keep morale up, I think. And it's a marvelous way to share culture.”
Before Senku can preemptively veto the idea, Ryusui, passing by just outside the lab with Francois at his side, halts so abruptly he nearly spills his teacup. Francois, unflappable, rescues it without a drop lost, but Ryusui has already spun around, snapping his fingers like a conductor cuing an orchestra.
“Yes! I want it!” he declares, eyes gleaming.
Senku doesn’t groan aloud, but the urge is there. Of course. Ryusui getting involved means the whole thing will balloon into spectacle, lavish and distracting.
“We can form a band,” Ryusui says, swirling into the lab, looking delighted. “Ukyo can of course sing, since we all know he has the voice of an angel.”
Apparently news of Ukyo’s skills have spread farther than Senku thought. Ukyo’s blushing; his ears are bright red against the white of his hair.
“Do you play an instrument, dear Ryusui?” Gen asks curiously.
“I have had extensive training in the arts,” Ryusui says with great pride, planting a hand on his chest. “Dance, painting, and music were standard expectations, of course. I was trained on the piano.” His grin sharpens into something wolfish. “And naturally, I also learned the sexiest of instruments.”
“Saxophone?” Gen guesses hopefully.
Ryusui blinks, as if startled by the suggestion. “No, the guitar.”
“Ah, not the sexiest then,” Gen says cheekily, flicking his wrist in dismissal.
Senku, only half-listening, finds himself frowning faintly. What was supposed to be so alluring about a saxophone? Byakuya had always liked them. Then again, Byakuya had also been fond of bagpipes, so maybe his sense of “sexy” instruments wasn’t a reliable measure.
“If it pleases you, I can also play the bass,” Francois says, bowing slightly. “Or metal guitar.”
Ryusui spins around, almost knocking the cup out of Francois’s hands. “Francois! You’re into metal?”
Francois - rosebud mouth curved into one of their secretive little smiles, blue eyes glinting with laugher, shrugs coyly. “We all must have some hobbies in our leisure time, sir.”
“Oh, I do love this idea!” Gen says, clapping his hands together. “Everyone’s been working so hard on the boat and searching for oil. Some kind of show could really benefit everyone, allow for some fun and relaxation. I can do some magic, dear Nikki could demonstrate some judo, dear Ruri and the Sparkling Sisters could show off some of their dances…”
“Is this necessary?” Senku cuts in, not looking up from his notes. “We have to finish the boat. We still don’t know where the oil is.”
“Fun is a cornerstone of the human experience!” Ryusui booms, snapping his fingers again as if summoning trumpets from thin air. “We are not automata! Nor should we strive to be. Time to breathe, to savor, will sharpen us, not dull us!”
“True,” Gen agrees smoothly, tilting his head toward Ryusui with a knowing smile. “There are entire studies on the importance of play in psychology. Breakthroughs often come during rest.”
Senku tells himself that little thrill in Gen’s tone is just Gen being dramatic for the sake of the conversation. But he can still picture the way Gen’s eyes had been shining earlier - warm, unguarded - when looking at Ukyo, and the comparison makes the back of his neck itch. He sticks his finger in his ear defiantly.
“It’d be nice to take a break too,” Ukyo says from his corner, a small, wistful smile curving his mouth. “And I have missed singing. It’d be wonderful to share our music with all of the villagers. They've really only heard Lilian's song, and while it is amazing, the quality of the recording isn't the best.”
Ryusui beams, looking as though he’s just been handed another ship to captain.
“I will inquire if Master Kaseki is familiar with instruments,” Francois says smoothly, already pivoting toward the door. “I shall commission a guitar, a bass guitar, and a drum set from him.” They bow once before departing, steps silent, posture flawless.
“They truly are prepared for anything,” Ukyo notes wryly, tilting his head back.
“It’s why they are the most desirable butler in the world!” Ryusui boasts.
Gen laughs, soft and easy, and the sound lands somewhere between a distraction and a dare in Senku’s mind. “We truly benefit from your greed, dear Ryusui,” he teases.
“Careful, Gen,” Ukyo warns, “if we flatter him too much his head will swell and we’ll have to cut open the door to get him out of here.” Gen laughs so hard at that he actually starts snorting - an ungraceful, unpolished sound that still manages to pull the corners of his eyes into crinkles. Ukyo joins in, their shoulders tilting toward each other, the air between them bright with shared humor. Ryusui looks mildly affronted, which only fuels their amusement.
Senku stares at his notes, the graphite smudge on the side of his hand dark and grainy. He tells himself it’s all background noise. It’s just harder to believe when the background noise keeps laughing.
—
The thing is, Senku does actually like Ukyo. He’s smart as a whip, thoughtful, sharp, and strategic. He’s got a strong set of morals he abides by. Ukyo truly dislikes bloodshed. He once asked, in all seriousness, if Senku could figure out how to make tofu again, because he’d been vegetarian in the old world.
Senku, who has been accused more than once of being amoral - or worse, some cold-blooded utilitarian - knows the world is messier. He’s practical. He cuts corners where he can, throws his energy where it’ll count the most. Efficiency over sentiment. But that doesn’t mean he despises sentiment. He respects people who stick to their values, who don’t bend just because the world does.
It’s why he likes Ryusui - he’s greedy, sure, but in an ambitious way, a way that seeks to make the world better. Ryusui isn’t greedy for things like cryptocurrency or abstract domination - he’s greedy for a world in which everyone can see their talents fully realized. Chrome, too - he’s willing to throw himself into things, full-heartedly, unsure where the bottom is, because the allure of the unknown is too strong not to.
The Kingdom has benefited a lot from having Ukyo around. He’s diligent, patient, and compassionate. His presence makes it harder for fights to spiral, not just because he’s decent to his core, but because he’s also the kind of guy who can loose an arrow so close it parts your hair if you step out of line. Ukyo’s the embodiment of speak softly and carry a big stick, except his “stick” is so precise it could thread a needle midair.
Senku knows all this. Rationally, logically, he respects Ukyo. He even likes him.
So why does it twist in his chest when Gen leans too close, laughter bubbling unguarded in Ukyo’s direction?
Gen, too, has his own set of values. He pretends otherwise, wrapping himself in the persona of a slippery opportunist, the world’s most self-serving con artist. But Senku knows better. This is the same Gen who calculated his birthday, just so he could give him a gift. The same Gen who groans about manual labor but still picks up the slack, the same Gen who risked being torn apart by anyone furious about him impersonating Lillian. Gen likes to act like the world’s most immoral man, but like Ukyo, he’s fundamentally decent.
Maybe even more decent than Senku deserves.
Gen’s chaos is different from Ukyo’s measured calm - restless, quicksilver, unpredictable - but that’s not a high bar to clear. The only person with less chaos than Ukyo is Kinro, who looks like he’s going to rupture a blood vessel if someone even suggests bending a rule.
And yet, Gen and Ukyo seem to work together well. They agree on the value of frivolous-seeming things: fun, art, music. Ukyo has some of the same sense for people that Gen does, though he’d never in a billion years twist it into manipulation the way Gen can.
It’s not a sense Senku has, nor one he ever will. Gen has to be there, acting as his filter, softening his blunt edges, making his logic palatable enough for everyone else to follow. Without Gen, his plans would have been stopped by Magma beating the shit out of Chrome. Hyoga would have killed them if Gen hadn’t been willing to act as a double agent. Senku would never have gotten Nikki over to his side, let alone Ukyo.
Sometimes, late at night, when Senku jerks awake from a sleep he hadn’t meant to slip into, he finds himself covered by a blanket and the mentalist curled up on the mat next to him, pale hair falling across his face. And in the dark silence, the thought creeps in before he can shove it aside: Does Gen ever get sick of it?
Senku tells himself it doesn’t matter. Gen will stay as long as it’s useful to him. That’s all there is to it. They don’t need to be the kind of friends who can whisper about everything. They’re here by a fluke, rebuilding a broken world.
Because in the modern day, none of this would’ve happened. He’d never have found out that Gen is brilliant, sharp-tongued, and unexpectedly kind - he would’ve been just another figure on the TV, a grin on billboards. Ryusui would’ve been a name in some business magazine, an eccentric millionaire halfway across the world. Ukyo, a total unknown. Chrome and Kohaku wouldn’t have even existed.
A different world, a different set of equations. No kingdom, no laughter over cracked stone floors, no blanket tugged over his shoulders in the middle of the night. No gifted observatory with a telescope made from half-remembered equations, no tears at a homemade cola.
Senku can’t put into words why the thought leaves him hollow, why it feels as though his blood and bones have been scraped clean from his skin. It isn’t just nostalgia or regret - it’s a sense of loss for possibilities that never existed, for connections that only the collapse of one world could have made possible.
But he forces the thought aside, like a stubborn tool that won’t fit where it belongs. It’s not worth dwelling on hypotheticals. He’s here, now, in this fractured but alive world. Despite all the improbabilities and impossibilities, Gen is right next to him.
And that, Senku realizes with a pang he doesn’t quite name, is enough to make him wish - just for a fraction of a second - that he could measure the world not in formulas and experiments and how close they are to restoring everything to the way it used to be, but in something like this.
—
Shortly after finding the Sagara oil fields - and what a relief that is - Senku finally hears Ukyo singing. The others are full steam ahead on their variety show idea, and Senku doesn’t have much of an argument left against it. The Kingdom of Science and the Empire of Might have been grinding through nonstop labor for weeks, and while his own solution to burnout is “work faster,” he knows most people aren’t wired that way.
Besides, the seams between the two factions still show. Coordination is shaky at best, suspicion lingering in small, silent ways. Magma and Yo’s constant bickering is just the most obvious crack in the plaster. The modern-timers mutter under their breath about the villagers’ primitive habits; the villagers, in turn, find the modern-timers both condescending and strangely incompetent at things as basic as not dying.
It’s a daily reminder that boiling water, to some, is an instinct. To others, it’s an experiment. And that gap, like most gaps, takes more than logic to close.
Whatever. Gen, Ukyo and the others are the ones dealing with it, and they seem pretty sure a variety show will help. The most Senku has done is give them some lightbulbs, but they already had extra for Yuzuriha’s fashion show.
Senku’s crouched over a makeshift pump system, forearms smudged with oil. Something in the line’s clogged - he’s narrowed it down to either sediment build-up from someone improperly flushing it or some idiot (probably Ginro) thinking the intake pipe was a convenient place to drop a rock. He’s so deep in calculating flow rates and PSI adjustments that he almost misses the sound drifting toward him.
The song isn’t loud - more a cresting wave than a wall of sound - but there’s a pulse to it, quick and restless, like wind rushing over open water. Ukyo’s voice rises with it, never straining, carrying that strange, airy momentum that makes you feel as if you might lift off the ground if you listened too closely. There’s something unguarded there too, a flash of joy so sudden it almost reads like defiance.
Senku’s never been good at dressing thoughts in pretty language. Byakuya had loved poems about cherry blossoms drifting on the wind; Senku had preferred schematics and formulas. His English had come from cartoons, technical manuals, and journal articles; Byakuya once joked that Senku’s second language was really “lab report.” But even without the words clicking neatly into place, he gets the gist, the feeling of being swept away.
He wipes sweat from his forehead, smudging another streak of grease into his hair, and forces himself to look up. Across the clearing, Ukyo is mid-song, sitting at the edge of the clearing in the car Gen had driven over, the sunlight threading gold through his hair, catching the sharp line of his jaw. Ryusui leans forward, enraptured, eyes wide and smiling as if each note is a treasure handed directly to him.
There’s motion besides the car - Gen, perched on a crate like a cat listening to a distant rustle, head tilted, eyes half-lidded. His expression is open, relaxed, fond in a way that makes Senku’s chest tighten. It’s rare to see Gen so unguarded, so completely captivated by something other than a scheme or experiment.
Senku’s fingers tighten on the wrench until the metal bites his palm. He turns and busies himself with the pipe.
Ukyo’s song trails off, and there’s a smattering of applause from the duo watching him. “You truly do sing like an angel!” he hears Gen say with an exaggerated sniffle.
Ukyo laughs, slightly out of breath. “Will you stop harassing me to sing for you now?”
“Oh, never, now that I know the rumors of your talent weren’t hyperbole! You will delight all at our little show.”
Senku grits his teeth, feeling the sharp sting of jealousy flare in his chest. He tells himself it’s irrational - Ukyo’s singing is technically impressive, and Gen is just being Gen - but the sight of the two of them, easy and amused together, makes his hands shake slightly against the pipe. He swallows, focusing on the hiss of oil seeping through the joint, the rhythmic scrape of his wrench, trying to drown out the warmth radiating from the other side of the clearing.
“If anything, you were underselling your talents!” Ryusui says.
“Well, if we ever depetrify my mother, I will pass along your compliments,” Ukyo says wryly, a hint of wistfulness threading his tone.
“Where are your parents? Were they close to Tokyo at all?” Gen asks.
“They were off visiting my dad’s brother in Västerås when the petrification hit, so I would imagine they’re somewhere there still,” Ukyo says, somewhat longingly. It’s an unusual tone for him - Ukyo’s always been a touch more stoic. It’s strange to imagine him as someone with a family he spent time with. “What about you, Gen? Is your family nearby?”
Senku’s ears perk up despite himself, and he forcibly makes himself consider the pipe with even more focus than before. Gen rarely talks about himself. It’s not until this question that he realizes he never thought of who Gen was in the modern day when he wasn’t busy being Gen Asagiri, famed/shitty mentalist.
“Ah,” Gen says, sounding faintly surprised. “Well, to be honest, I’m not sure. Before the petrification, I hadn’t spoken to my mother in months. My father…he was lost to the winds years ago. Although I wouldn’t mind finding my manager at some point, if only to tell him that book he made me write got me mocked by the Prometheus of the new world.”
Senku freezes slightly at the phrase. Is he talking about me? He’s not one for flattery, but there’s a warmth to the thought - this is how Gen sees him, as someone shaping the world, bold enough to challenge it. Something in his chest tightens, a mixture of pride, unease, and something else he’s not ready to name.
“Hey, you lot,” he calls across the clearing, more irritated than he means to sound, “stop fucking around and get to work. We’re losing daylight.”
“You seem to have it well in hand!” Gen shouts back, the faint teasing lilt in his voice carrying across the clearing. “Besides, isn’t music while you work much nicer?”
“That just takes up Ukyo’s time; stop looking for every excuse to get out of manual labor,” Senku snaps, though his voice carries less sting than usual.
“We should get to work,” Ukyo says, ever responsible, folding his legs beneath him as he tilts his head slightly toward the sun, which is beginning its slow descent. “Senku is right. It’s getting late.”
“Boo, look at you joining him in being a kill-joy,” Gen replies, his grin wide and mischievous. He can hear him get up and start hauling some materials out of the car, though. Senku has to swallow around the sudden lump in his throat, the faint sting of something he can’t quite name - maybe irritation, maybe envy, maybe a sensation that he’s doing something wrong again.
He’s never known how to speak to people, really. This is why he’s largely just had Yuzuriha and Taiju as friends - Taiju is almost as straightforward as he is, despite their differences in intellect, and Yuzuriha is capable of seeing what lies beneath his words, past his awkward phrasing, into the intentions he can’t articulate. Most people have always seemed mysterious to him: saying one thing, meaning another, performing social equations he can’t solve. He knows that when he tries to communicate, it often comes out harsher, sharper, or more intense than intended.
Senku hammers another wrench turn, gritting his teeth as he forces his attention back to the pipe, but he can’t entirely block out the laughter echoing from the car. It tugs at something stubbornly soft in his chest, and he’s suddenly aware of how tired he is.
He feels a gentle tap on his shoulder and looks up to see Gen holding a bamboo cup of tepid water. “Goodness, this pipe got you good,” he tuts. “You’re covered in grease. Drink up, dear Senku!”
The water is indeed slightly too warm and tastes somewhat woody from the cup. Senku drains it in one go, the liquid sliding down his throat, soaking the dryness that had built up over hours of labor and heat. He sets the cup down with a muted clink, wiping his mouth with the back of his sleeve, and finally allows himself a brief pause.
Gen’s smiling his usual coy smile, hands tucked into his sleeves. “You’ll need a wash later,” he says. “Luckily it shouldn’t be too much work to get you to the hot springs.”
“I can’t be that disgusting,” Senku says, handing back the bamboo cup.
“Oh, you’re absolutely revolting,” Gen replies smoothly, tone dripping with false horror. “Our great scientist, defeated not by a rival kingdom, but by sweat and grime.” His eyes glint, sharp but fond. “You’d better be careful. You’ll ruin that genius aura if you start smelling like sulfur.”
“Fuck off,” Senku says, grinning, and flicks a bit of the built-up grime on his fingers at Gen. Gen screams in mock horror and sprints away, laughing. He’s draped in gold from the lengthening light, and Senku doesn’t really know what to do with the way his breath catches.
Gen vaults over a crate, still cackling, nearly colliding with Ukyo, who steadies him with a hand against his shoulder. Gen leans close, murmuring something - Senku can’t hear it, but he sees the curve of Ukyo’s quiet smile in response, soft and effortless. They fall into step together, voices low and easy, and Senku’s jaw tightens.
He forces himself to wrench another turn into the pipe, metal squealing against metal. Focus. He just needs some more water and to wrap this up for the day. That’s all this is. Exhaustion. Dehydration. Definitely not the creeping irritation that coils low in his stomach as Gen tilts his head back and laughs again at something Ukyo says.
Senku knows he has no right to it. Rationally, logically, it doesn’t matter who Gen spends his time with, whose shoulder he brushes, whose voice makes him laugh like that. But the logic doesn’t stop the pulse at his throat from hammering, doesn’t stop the small, sharp part of him that wants to call Gen back - to keep him here, beside him, grease and sweat and all.
Instead, he digs back into the work, metal biting his palms, every turn of the wrench punctuated by Gen’s laughter drifting on the early autumn air.