Archive of Our Own ^beta

The winter this year is harsh and unforgiving.

Thankfully, the village isn't short on food. Senku drew up plans for a greenhouse several months ago, and through everyone’s effort the greenhouse interior is filled to the brim with crops like tomatoes, onions, peas, and spinach. Along with Francois' knowledge for recipes, cooking, and preserving food, everyone gets to eat their daily fill.

The huts are cosy with warmth, courtesy of Senku’s idea of a central heating system complete with a firebox, smoke passages, and a freestanding chimney. It’s an engineering feat, made possible with the right materials and skill.

There is relief that the village will live to see through another winter. Villagers both young and old praise Senku with straight up adoration, and continue to pour in the manpower he needs to continue inventing bits and bobs that take them closer to modern civilisation.

Gen isn’t surprised. He thinks he understands, because Senku is indeed nothing short of incredible. Senku has grown taller over the past year, has muscles that are more defined than Gen remembered. Senku's strength is still laughable compared to Taiju or Kohaku, but still. Gen allows his eyes to wander, to linger over Senku a little longer. He does that when Senku's engrossed in an experiment; does that when Senku laughs like a maniac over a new discovery. Gen also makes it a habit to watch directly over Senku's shoulder, marveling over both man and said man's scientific inventions. Senku always allows it, but of course Senku doesn't know that Asagiri Gen is a creepy stalker with the emotional capacity of a pining teenager. 

Gen knows it's bad, okay, but he really can't help it.

It’s fine though, because plenty of people like looking at Senku too. Senku has this effect on people after all. It’s weird, it’s brilliant, and even until now Gen continues to be surprised by what Senku can do. The list is neverending. It seems that every time someone comes to Senku with a request, Senku fulfills it with the tenacity and scientific passion of a madman. 

On the other hand, Gen is at his best when he's forced to think on his feet during a critical situation --- he performs well when he has to lie and cheat to survive. It's natural for a mentalist to be able to do that much, but Gen knows he doesn’t have much else to offer. He has a passable amount of scientific knowledge from whatever he picked up in high school (back when high school was still a thing, ha), but he’s nowhere near Senku’s level. He’s better than Chrome, but that's only because Chrome hasn’t been exposed to the same kind of education Gen has. Gen can’t fight like Kohaku; can’t swing a spear around like Kinro or Ginro can. He can’t craft useful things like Kaseki; doesn’t have fingers as nimble as Yuzuriha.

Gen is still reflecting on this depressing realisation when the doors of his hut burst open, revealing a trail of gleaming sunlight and a blast of wintry air. Even with the improved heating system, Gen finds himself shivering. Actually, he has been feeling strange since yesterday. For some reason everything aches, and there's definitely rawness in his throat. He thinks it might just be all the exposure to the cold air in the forest from yesterday, but…

“Oi, mentalist. Are you sleeping in? I told you that I needed help with building another generator today. The old one’s falling apart.”

Ah, it’s Senku. Here to bother him with more boring labour again. How lame. Gen casts a lazy glance from the sitting position he's in, blinking at a familiar set of ruby eyes.

“Are you meditating or something? Why are you sitting in the dark like this?” Senku asks, tilting his head. Gen gets distracted by the new reddish-brown fur coat that Senku is wearing, most likely fashioned out of some animal. Senku looks good. Like, really good. He stares, unabashed, at the way that Senku has the fur coat cinched around his waist with a sturdy leather belt, accentuating all the smooth lines and angles of his body. 

When Gen speaks, he almost doesn’t recognise his own voice. His throat is parched, the words coming out dry and scratchy. “I’ll be out in a minute.”

Senku raises his eyebrows in the way he does when he’s unimpressed about something. Then he strides over, kneeling so that his face is right next to Gen’s.

Gen yelps. He wonders if this is how a trapped animal feels like. “Senku, what are you doing?”

Senku presses a hand to Gen’s forehead before leaning back, the same unimpressed look still on his face. “I knew it.”

“Knew what?”

“You’re sick,” Senku accuses.

Gen responds reflexively. “I most certainly am not.”

“You are.”

“…I’m not.” But this time, Gen doesn't feel so sure. 

“Let’s see. Your voice is scratchy from a sore throat. You’re sniffling, even inside the confines of this heated hut. But the most telling thing is your temperature.” Senku frowns. “You’re burning up, mentalist. Didn’t you realise this?”

“I…no. I don’t get sick often.” Back then, Gen always boosted his immunity with constant doses of vitamin pills. He kept his hygiene levels up and spent most of his days inside, avoiding the cold Japanese winter from the warmth of a kotatsu. It makes sense that his body is choosing to fail him now that he’s out in the wilderness. “But I can still help,” Gen offers, even when his body protests at the little bit of movement he makes, “what was it you said about the old generator?”

“You are not doing anything today.” Senku pushes Gen down, looking around the hut. “Where are your blankets?”

“There,” Gen says, gesturing at one of the thinner flax blankets that the villagers made for him a few months ago. It's worn around the edges, some of the flax weaving unravelled.

Senku groans. “Are you kidding me? No wonder you’re falling sick. Why didn’t you ask the others to make you a warmer one for the winter? Stay here, I’ll be right back.”

Gen thinks he must have dozed off, because the next thing he knows Senku is nudging him awake. The blanket Senku piles on top of him is heavier, made of the same reddish-brown fur that Senku’s coat is. At Gen's curious glance, Senku says, “we don’t have any spare blankets in the village, so you can borrow mine for now. It’s not as well-made as it could be since I’m not an expert in stitching and sewing, but it’s warm.” Then he shoves a pillow under Gen's head for good measure. 

Gen’s mouth goes very dry. “You made this?”

“Ten billion per cent,” Senku confirms.

“It’s…quite soft.”

“Isn’t it?” Senku is beaming. “It’s from the red foxes in the area.”

That explained the colour and softness. “Senku, I can’t take this. What are you going to use to sleep?”

Senku rolls his eyes. “I’m staying here, of course. Someone needs to monitor your condition, and I don’t think anyone else is better suited to do that than me.”

Gen makes an offended noise. “I don’t need babysitting. You make it sound like I’m dying, Senku.” When he receives silence in response, Gen prompts, “you realise that this is probably just some stupid cold, right? It’s not a big deal. Really.”

“…Yeah. Yeah, mentalist.” Senku grins, but Gen notes that the scientist's heart isn’t quite in it this time. “I’m sure you’ll be back to being an insufferable asshole after a quick nap.”

***

Gen wakes up a few hours later feeling worse. He's hot, sweaty, and freezing all at once, made worse by the persistent headache building at the back of his skull. His clothes are plastered onto him like a second skin, which is also gross and unattractive. It feels like deja vu, him incapacitated in a hut and breathing heavily like a wounded animal. 

Kohaku is sitting next to him, a bowl of something in her hands. “You look like shit,” she says in lieu of a greeting. 

“Nice to see you too,” Gen wheezes. He doesn’t retort, because there’s no point denying something that is blatantly true.

“Here.” She thrusts the bowl at him, its contents sloshing noisily.  

“I’m not hungry.”

Kohaku doesn’t even blink. “Senku says you have to eat something, even if you don't feel like it.” 

Orders from Senku, huh? He takes the bowl with shaky hands, spooning the contents into his mouth with slow determination. It’s warm, with hints of herbs and spices to it.

“It’s our standard broth, but Senku made sure we added some extra ingredients to it,” Kohaku explains.

Now that Gen focuses, he thinks he tastes ginger, pepper, with a faint sweetness that just might be raw honey. Not a conventional recipe, but somehow it works.

“I think they’re also making some medicine for you. Senku called it…a-se…a-se-something…”

“Acetaminophen,” Gen finishes for her with a sigh. Typical Senku, doing his best to play doctor. “It’s a standard drug we use in my time to bring fevers down.” Gen has no clue how acetaminophen is made, but it should come as no surprise that Senku does. If asked, Senku could probably develop a whole host of vaccines in his spare time, because it’s fucking Senku.  

The steely expression on Kohaku is gone. She twirls a lock of hair, looking wistful. “Sounds incredible. We never had anything of that sort. When my people had fevers, they either got better or…or died. Some called it God’s will. With Ruri's illness, Chrome and I did everything we could, but even with our best efforts, nothing we did helped. Not in the way Senku's science did. His knowledge will truly save many.”

“Without you and Chrome, your sister would have died before Senku could even meet her,” Gen says bluntly. “Senku is incredible, yes, but don’t sell yourself short.”

Kohaku’s hand stills. “That’s probably the nicest thing you’ve ever said to me.”

“I’m full of praises for anyone who deserves it.” 

“You praise Senku more than anyone else, though,” Kohaku observes.

Despite the innocence of her words, Gen can’t help but stiffen. He feels like the kid who got caught eating from the cookie jar. “Senku deserves it.”

“Is that so?”

“Why, do you disagree?” Gen retorts.

Kohaku shakes her head. “Of course not. Everyone knows Senku is a great man. But I’m an observant person, Gen. I’ve seen the way you look at him.”

“I observe everyone. It’s, you know, part of what I do? As a mentalist.” It’s not exactly a lie. Gen observes everyone and everything. The more he knows about people, the more he can understand what makes them tick. And the more he knows what makes them tick, the more he can manipulate them when he wants to. Senku is a tough nut to crack, so Gen watches him a little more. It’s only natural.

“You do more than just observe him,” Kohaku argues. “Sometimes you look at him like he’s the only thing you see.”

Gen opens his mouth to refute this, but finds that he doesn’t have anything to say. He doesn’t think that his idolisation of Senku is anything to be ashamed of, but it is a problem if Kohaku, of all people, notices. Gen wants to retain his image of being a superficial man with superficial needs. It wouldn't do for anyone to think that he’s going soft.

They both jump when the doors open to reveal a triumphant-looking Senku, a vial of liquid in his hands. There are clumps of powdery snow on Senku’s gravity-defying hair, meaning that it is snowing outside. “Acetaminophen’s done! Kohaku, can you get us the other stuff that I asked for?”

Kohaku nods, exiting the hut. Something in her gaze tells Gen that their conversation is far from over.

“Acetaminophen, really?” Gen asks, eyeing the liquid with suspicion. He knows that there's no reason for Senku to try and poison him, but Gen can’t stop his old instincts from acting up. Being a former double agent working against Tsukasa’s empire meant that he was always on guard, never letting his façade slip.

Senku takes no offence to Gen’s wariness. Instead, he launches into a lengthy explanation on the subject of making-acetaminophen-101. By the end of it (and in which Gen failed to understand about 80% of said explanation), Gen finds himself relaxing. He drinks Senku’s home-made acetaminophen, satisfied that it’s not going to kill him.

“This is quite impressive,” Gen says, wiping his mouth with the back of his sleeve.

“Bringing down the common fever with acetaminophen? Now that is exhilarating.”

“I’m serious. You didn’t have to spend your afternoon making this. I’m grateful, Senku.”

Senku shrugs. “Eh, we would have needed it eventually. Humanity's going to need all the medicine it can get to stay healthy and alive after de-petrification.” There is something sombre in Senku’s expression, something that looks almost remorseful. “After all, science can do many things, but it can’t always save a life.”

Before Gen can respond, Kohaku throws open the doors to reveal a large, steaming vat of water, a bar of soap, wash cloths, and a towel. She sets everything down, winks blatantly at the two of them, and walks out.

“That gorilla,” Gen mutters. He takes stock of the hot water, the soap --- and thinks he knows what this is for. “You asked her to prepare a bath for me? Really, Senku?”

“Soaking in warm water will help with the fever. The soap’s just a bonus, because I figured you’d feel gross after all that sweating. Go on, enjoy it.”

Gen stares. Senku stares blankly back.

“Are you just going to be here while I do this?” Gen asks, when they make eye contact for five seconds longer than necessary. “My clothes are going to come off, you know.”

Senku points at the blanket. “I’m staying here tonight, remember? If it bothers you that much, I won’t look.”

“Of course it’ll bother me! What kind of weird pervert have you turned into?!”

“And here I thought you were the pervert. Weren’t you the one who dreamed of a harem of cute girls?” Senku asks, turning away. He spreads out a large manuscript in front of him, clearly intending to work while Gen has his bath. 

“A harem of cute girls would be annoyingly difficult to take care of,” Gen mutters, slipping the folds of his makeshift Japanese-styled kimono off.

Senku hums in agreement. Comfortable silence descends as Gen sinks into the water, sighing in bliss as warmth envelopes him. It feels like a heavenly Japanese hot spring. Gen shuts his eyes and listens to the sound of whispering parchment; to the occasional sounds Senku makes when he works --- and knows, truly knows, that he made the right decision long ago by siding with the kingdom of science. 

He must have nodded off once again, because Senku is shaking him gently by the shoulders. 

“Don’t wanna leave the warmth,” Gen slurs. 

He thinks he sees a fond smile on Senku’s face, but that must be the sleepiness talking. “I know. But if you towel yourself dry you can get under the blankets, and then we can go to bed. Sound good?”

“Hrrmmm,” Gen responds coherently. 

By the time Gen dresses, Senku is already under the covers. It’s ridiculous how the blanket is large enough for two, but Senku must have foreseen that he would one day have to share his blanket with someone else. Senku pats the space next to him, and Gen slinks in with the bonelessness of an exhausted man. They’re so close that their arms are touching.

Senku is truly an excellent source of warmth, so Gen wriggles closer. 

“Warm enough, mentalist?”

“Mm, yeah.” The acetaminophen must be doing its job, because the headache and feverishness is fading.

Outside, the wind howls. A snowstorm, Gen thinks. He yawns loudly, asks, “how much did you overhear from my conversation with Kohaku earlier on?”

Senku chuckles, doesn’t even question how Gen knows. “I didn’t mean to eavesdrop at all. But since you asked, I won't lie. I overheard everything." 

Well, that isn't a surprise. Gen asks, “are you bothered by anything we said? Some of it was pretty gross stuff.”

“Hmm, I don’t think so. I mean, you’re always gross…”

Gen kicks him.

“…Ouch. Yeah, you’re always gross, but it’s what I like about you.”

“You like me because I’m gross,” Gen deadpans. 

“I mean, science still ranks way higher than you, but you come pretty close.”

It’s the worst attempt at flirting that Gen has ever witnessed, but coming from Senku, it’s practically a marriage proposal. Gen cheers internally, his mind a repetitious chant of Senku likes me! Senku likes me! Senku likes me! Senku…

“Senku.” Gen's curious about something and wants to hear this from Senku himself, even if part of Gen already knows the answer. “Do you feel guilty about not being to save everyone?” Gen’s mind wanders to the stone statues that are weathered, brittle, fraying away with no chance of revival; Tsukasa in his current frozen state; villagers that couldn’t be saved; people they have lost along the way...

Because it’s Senku, he doesn’t yell at Gen for the invasive question, nor does he attempt to change the subject. He makes a thoughtful noise, thinking for a while before saying, "guilt isn’t the right word. I’m ten billion per cent certain that we'll save most of humanity with science. It’s just…”

“You wish to conquer the challenge of being able to save everyone.”

“…Something like that.” Even in the dark, Gen can tell Senku's expression is weary. “I don’t feel a lot of things like most people do, mentalist. Taiju mourned over Yuzuriha, desperate for her revival every single day. Ugh, you should have seen him, he was insufferable. Tsukasa was hurt over the loss of his sister, which led to his mentality of allowing only a certain selection of people to survive. Kohaku and Chrome wanted to save Ruri. In other words, people act when they have someone they want to protect. But me?” Senku chuckles, a hollow sound. “I see opportunity. I see challenge. I see things I want to overcome. Science is my playground, and everything is an experiment. Saving as many people as I can comes within that territory, but I don’t feel the remorse or desire to protect others like the others do.”

Gen knows he has to be careful with his next words. He doesn’t want to make Senku angry, but he needs Senku to understand. Naturally, what comes out from his mouth is, “I think that’s a whole lot of bullshit, Senku.” He even drawls out the honorary chan after Senku's name for extra effect. As expected, Senku stiffens against his side, but Gen knows the scientist isn’t going to lose his temper without a rational debate first.

“Prove me wrong then, mentalist. You understand humans better than I do, so tell me…” Senku’s whisper is low and rough in Gen's ear. “…What exactly is it that you see in me?”

“If all you truly cared for was the glory of science, you wouldn’t even have done half of what you've done here. You would need manpower from the village, yes, but you didn’t need to save Ruri or encourage Chrome’s efforts in science to get it. You could've forcibly wrestled power from the chief with gunpowder and firearms, none of that participating in the village games crap needed. You could've so easily been another Tsukasa, fuelled by science instead of might.” Senku isn’t saying anything yet, so Gen takes it as a sign to continue. “Also, I heard from Yuzuriha and Taiju. You saved their lives and allowed Tsukasa to kill you, so that none of them would have to die. Quite selfless, don’t you think?”

“That,” Senku splutters, “with a ten billion per cent certainty, Yuzuriha and Taiju would have figured out how to revive me eventually.”

“Hm. Selfless, brilliant, and brave,” Gen teases. On impulse, he laces his fingers around Senku’s, biting back a smile when Senku doesn’t pull away, “what else do I have to say to convince you, Senku?”

“I use people, Gen. I’m not exactly hero material.”

“You’re fair and reasonable,” Gen corrects. “You give them your knowledge, they give you manpower. It’s a trade. But you make them see the worth of entrusting their hopes and dreams to you, so that they trade with you freely. Willingly.” In this enclosed space with just the two of them, Gen allows himself to be honest. “Everyone sees their worth because of you. Humanity needs you.” I need you, Gen’s mind traitorously supplies. “Now me, on the other hand…”

“Hm?” 

“I’m a superficial person through-and-through. I’ve said this before, and I’ll say it again: I have no morals, no loyalty, nothing important to hold on to. No lofty ideals, no kindness, no impulse to save anyone whatsoever. I’m just a side piece on this huge chessboard. You probably have some screws loose to see anything in me, Senku.”

There’s a few seconds of silence, then Senku elbows him. Hard. Gen lets out a yowl that sounds like an injured cat. 

“For a mentalist, you’re dumb as shit sometimes.” There’s something like wonder in Senku’s voice, the same tone he uses whenever he has a scientific breakthrough. 

“Hey, I take offence to that.”

“No, seriously. Do you really see yourself in that way? You, a side piece? How many missions have we been on together? How many enemy bases have we raided as a team?" 

“And on all those missions, I've not been good for much except being an asshole to people,” Gen says.

Senku's head falls onto Gen’s shoulder. “Oh my god. I can’t believe the mentalist is so stupid.”

"You're whining," Gen protests, feeling defensive all of a sudden, "why is the great Senku whining?" 

“Asagiri Gen, you dumb mentalist,” Senku announces, flipping their positions so that he’s straddling Gen, “can’t you see that you’re my right hand man?”

Gen’s mind screeches to a halt. “Your what now?”

“My right hand man? You know, like when the prime minister has a deputy prime minister? When the king has an advisor? That’s what you are, in case you didn’t know. You’re my sounding board for strategies. In fact, you create many of those strategies. Whose idea was it to use Lillian Weinberg’s song against Tsukasa’s army? Who knows enough about modern day science and knowledge on warfare to understand my perspectives? That’s you, idiot.”

Gen flushes. “Those are little things, Senku.”

Senku ignores him. “What was it that you said again? Hmm, if I recall, it was something along the lines of ‘Ishigami Senku and Asagiri Gen will happily fall into hell together’? Quite the bold declaration. It was exhilarating to hear.” Then Senku grinds down, hard, and Gen swears he nearly sees stars.

Still, Gen laughs weakly and hopes Senku can’t hear how much of a wreck he is. “It’s only natural as a right hand man to say things like that, right?”

“Perhaps. But you were also the one who gave me a gift.” Senku’s gaze softens, his expression transforming into something less devious, more open. “Rallying the others up, building that observatory for me with whatever knowledge you had. Remembering something as ridiculous as my birthday, even when I never told anyone about it. Do you still think you have no kindness or loyalty whatsoever?”

Gen exhales. “You don’t know what you’re saying. From the very beginning, my only intention was to be on the winning side. I protect my own interests, and it just so happened that yours aligned with mine. Maybe I wanted to boost your morale, keep your spirits up. That’s all part of what I do as a mentalist.”

“And?”

“And? Senku, I don’t do things out of the goodness of my heart.”

Senku reaches out with a hand to ruffle Gen’s hair, before using it to cup Gen’s (flaming red) face. “Then we’re very much alike.”

“I suppose s --- damn it, I’m supposed to be the mentalist, not you! Stop trying to change my mind!”

“Oh,” Senku looks down. “You’re hard.”

“You --- you --- what do you fucking think?” Gen hisses, more embarrassment creeping up on him. “I can’t help it, when you’re sitting on me like that!”

“Like this?” Senku asks innocently, hips moving in a way that's just scandalous. 

He’s hard too, Gen realises. What a cheeky little shit. “It’s not fair. You’re a science nerd! You’re not supposed to be good at…whatever it is you’re doing.”

“I accept your compliment, but I’ll admit that I’ve never done anything like this before.”

That makes Gen pause. He can’t believe his ears. “Really? No ex-girlfriends of any kind? Never experimented with anyone, not even with Taiju? Kohaku?”

Senku’s face twists into horror. “Don’t say anything like that ever again. You’ll scar me for life. No, I don’t have ex-girlfriends. Taiju’s very much in love with Yuzuriha. We’re all childhood friends, so that would be weird. Kohaku’s a gorilla, so she doesn’t count.”

“Oh,” Gen says simply. He doesn’t know whether it’s relief that’s coursing through his veins, but he allows himself to melt into Senku’s touch. “Okay.”

Senku’s hands are rough and calloused from hard work, and he’s also inexperienced. Still, Senku takes all the time in the world to observe Gen’s reactions, cataloguing the kinds of movement that make Gen sigh with pleasure. His fingers linger on Gen’s bare neck for a moment before moving to explore the de-petrification scar on Gen’s face. 

“This scar…” Senku murmurs, more to himself, when he sees it on Gen's chest. It's an ugly thing, grazed and bumpy in the ways that skin usually isn't. 

“From when Magma attacked me.”

Senku’s touch is feather light. “I see.”

“You’re being very thorough, Senku,” Gen grits out. He’s aching to be touched.

Senku shrugs. “I’m not in a hurry. Besides, it’s only normal for a scientist to want to observe the things he’s interested in.”

“Lies. You just like watching me squirm.”

“And if I do?” Senku’s ruby gaze is dark and intent.

***

Gen allows Senku to drown him in pleasure over and over again.

It’s messy, sometimes a little awkward, but it is also the most perfect and wondrous thing that Gen has ever experienced. Gen falls apart in front of Senku, keening and whining for more, nails embedding crescent scars on the planes of Senku's back. And Senku --- Senku is patient, even when the hunger in his eyes is unmistakable, even when Gen is a writhing mess of nonsensical words beneath him. Their breaths intermingle and Gen closes the distance to seal his lips over Senku's, because it has been three thousand and seven hundred years, humanity is in a dark place, and Gen can't think about anything else except how wonderful and perfect and beautiful Senku is. 

Senku freezes, but only for a moment. Then he's kissing Gen back, at first experimentally, then with more force and need. There's a brief tussle for dominance and no one really wins because they're both equals, well-matched and well-suited to challenge each other. So they kiss some more, teeth occasionally clacking, until Senku playfully nips at Gen's lower lip in a manner that absolutely takes Gen's breath away. So Gen, competitive and unwilling to be outdone, latches onto the pale skin of Senku's neck and sucks. Senku makes a sound that can only be described as a moan, and Gen smirks.

It's ridiculous, the push and pull, the way they orbit around each other. 

They don't say their I love yous, but Gen doesn't think they need to. At least, not yet. There's time to say it in the future when they've done this some more, when they can understand and interpret each other's nuances on a level that no one else could hope to achieve. But they're pretty damn close to that level, whatever it is, because Gen feels contented, and knows that Senku is, too.