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Tsukasa

What is Ishigami Senkuu to Shishio Tsukasa? 

He doesn’t know how to categorise this feeling, and that troubles him. Him! Shishio Tsukasa, the strongest primate highschooler, best warrior of the stone world.

He told Senkuu once, that he thought they could have been true friends in the old world and perhaps that contributes to it, this feeling he cannot quite define. They aren’t exactly friends - can you be true friends after trying to kill each other? - but there is a bond there. There is respect, and a strange conditional trust, and a liking that Tsukasa feels for few people. Senkuu is science-mad and stupidly idealistic and bad with feelings but he has a purity of soul that Tsukasa can’t help but like.

Then there’s an element of fascination. Watching Senkuu's mind at work is a joy . He sees potential and possibility in everything and for all his insistence that he takes only the logical path towards his goals, he always finds time to improve the quality of life of those around him too. Tsukasa yearns to be half the benevolent leader Senkuu seems able to be without trying and it isn’t exactly a bitter feeling but he’d be lying if he said there wasn’t envy there. 

He considers “love” of course. He’s not stupid, he knows that’s where your mind should go when an individual becomes so incredibly special to you that their existence is unique and fills up your mind. It just also isn’t quite right. He’s never felt a lust for other males, and trying to picture expressing these undefined feelings with a kiss or caress just feels incorrect. 

The feelings aren’t dissimilar otherwise though. He certainly feels possessive of Senku. Watching Ryusui or Chrome sling an arm around the young man’s slender shoulders stirs a hot rage in Tsukasa, provokes a desire to tell them to back off . Kohaku also troubles him. Senkuu doesn’t seem to be in love with her - or even she with him - but she’s the most viable candidate and it irks him that she so naturally takes that place. He doesn’t even like that Taiju and Yuzuriha have an easy freedom to touch Senkuu that he isn’t allowed, though he understands how deeply irrational this is. 

Then there is the complex conundrum of what are Senkuu's feelings. He seems devoid of romance or sexuality, not in the immature way of a middle schooler but in a detached, adult way. He asks Minami if her travels have brought her in contact with such a phenomenon and she gives him new language like aromantic asexual and ace spectrum and queer-platonic partners . 

Minami has simple feelings for him, though the age gap makes her feel guilty for them. She lusts for him, she holds affection and respect for him, and he can easily see how he could nurture those feelings into love for him and how easy it would be to enjoy the benefits of that. He likes her company. He’s attracted to her body. He respects her mind and talents, and honestly their age gap is laughably irrelevant here in the stone world. 

Yet the feelings he holds for Senku, though love doesn’t seem right, do wriggle into the cracks of that uncomplicated premise and make him feel guilty, like he wouldn’t be engaging sincerely with Minami. 

He reframes the question. What do I want from Senku? 

Immediately, he knows he wants respect. He wants regard. He wants to take up space in Senkuu's world the way Senkuu takes up space in his and he knows instinctively that he would rather be arch enemies again than become casual acquaintances who crop up once every few months. 

He studies the people around Senku. Taiju’s role is perhaps the one he craves most. Taiju receives unconditional trust from Senku. Tsukasa isn’t sure anyone else has noticed but it is Taiju alone that Senkuu will allow his body to slump against if he’s tired or cold, Taiju who can touch Senkuu without warning and not receive that troubled little frown in return, Taiju who his eyes will scan for when he reunites with a crowd, those slender shoulders never truly relaxing until the “big oaf’s” face has been spotted. 

He wouldn’t mind Chrome’s, though he doesn’t particularly crave it. Chrome is Senkuu's friend, yes, but also his apprentice. Tsukasa would like the focus and care Senkuu lavishes on Chrome, but he would dislike the subordinate relationship that the two of them struggle to shake. But Chrome receives praise freely, and his passion for science means he gets to see that boyish joy light Senkuu's face up close and personal way more than the rest of them. 

He resents Ryusui greatly. There is no reason for Ryusui to have special meaning to Senku, but the greediest man alive has no problem verbalising and accepting his own complicated feelings. He craves Senkuu and he’s open about it, not bothering to obsess over lines like love or lust, platonic or romantic, reciprocal or rejected. Ryusui touches Senkuu whenever he wants. He might not get Taiju’s easy acceptance, but he will clasp Senkuu to his side through the tension until it leeches out and Senkuu goes docile. He can ruffle his hair, clap his back, hoist him up to praise him, hand feed him tidbits and even press their foreheads together and beam unashamedly into Senkuu's stoic face. Tsukasa is sure Ryusui’s ways must be a chore to Senku, something he tolerates for the man’s incredible usefulness in their many quests, but it irritates him that the questions that plague him and prevent him reaching out to Senkuu are simply irrelevant to Ryusui. 

He tries to imagine himself like that; perhaps celebrating a reunion by lifting Senkuu up into his arms or sharing a quiet moment of intimacy by feeding him a treat. It pleases him more than he likes to picture, and he’s no longer quite sure if he was right to dismiss what kind of touch he wants from Senku. He doesn’t want to exchange gratification with Senkuu the way he passively does with women in general, more appealingly with Minami, but he craves the right to touch Senkuu in a way that casual friendship doesn’t allow. 

He continues honing his strength. It’s imperative that nobody, not Kinro, Kohaku, Matsukaze, Magma, Yo or Taiju, is better able to protect Senkuu than he is. It earns him spots on voyages at Senkuu's side, it encourages the others to ally them. Senkuu is their mighty leader, the living library they cannot afford to lose and while Tsukasa is the strongest, nobody ever thinks to question that he should be at Senkuu's side. 

He also, just to let out a little of those frustrations from his unanswered questions, starts being a little more like Ryusui. It’s not his way to boldly take what he wants without asking, but he starts gently nudging the boundaries of their relationship to make sure they’re placed correctly. Little things, like draping his lionskin over Senkuu when the temperature drops, saving a place for him when the group sits to eat (not that Senkuu always takes it - for an unsociable man he has an endless stream of invitations for companionship), pre-empting any need he might have for strength. He wants Senkuu to slowly increase the priority he has in the Trust List, to be the person Senkuu defaults to for help, and it seems to be working, just a little. 

It starts one night in Europe, where a bitterly cold rain falls as they travel and Senkuu steps into the shelter of Tsukasa’s side without waiting to be invited. There’s a sheepish look, a silent acknowledgement that Senkuu is now the one testing the lines between them, and Tsukasa makes sure to accept him wholeheartedly, spreading the cloak to encompass them both. 

Senkuu starts looking automatically to Tsukasa when he needs assistance. He starts to subtly probe him for his preferences in their ever expanding arsenal of entertainment. He preempts things Mirai will need and provides them before being asked. He lays his sleeping bag close to Tsukasa’s if they break new ground without proper lodging. He - as a totally accidentally byproduct on the way to something else of course - makes shampoo and conditioner and combs for long, thick hair like Tsukasa’s. He voices complaints about his aches when they’re bathing in the hot springs and accepts Tsukasa’s massages to his shoulders or neck. 

It’s all improvement, but as the distance between them narrows, Tsukasa is alarmed to find his possessiveness grows. He’s gone from annoyance at people like Ryusui casually touching Senkuu to seething at the way Gen is always fluttering in the periphery, resenting the way Kohaku is allowed to lean on him when her immense strength tires, even jealousy at the way Suika snags his tunic in her little hands and trots after him. He still doesn’t feel like he needs or even wants something like sex from Senku, but he wants something that validates and solidifies his place with him. 

‘Yo, Tsukasa, what’s got you all brooding?’ It’s casually delivered, but from Senkuu it’s as emotional as conversation gets, and suddenly, Tsukasa thinks he’s figured out enough to say something . 

‘Senku… What do you want your life to look like when the Kingdom of Science is complete?’ 

Senku

Oh. So this is happening again. Senkuu felt the energy drain out of him at the question. 

He was seven years, three months, eight days old the first time this happened. Her name was Ashikawa Chiyo, she loved robots even more than Senku, and they had spent many happy hours talking robotics together.

Then one day, Chiyo’s big sisters had teased her about being in love and what if they get married one day and Senkuu had snorted in disbelief, turned to Chiyo to laugh with her about how stupid they were being and seen her with teary eyes and red cheeks. She’d pushed him away and told him he was a jerk and never talked robots with him again. 

Then there had been Hoshikawa Nao. She had been a friend of Byakuya’s who had come round often, they had dinner together, she wasn’t very sciencey but she made Byakuya smile in a way Senkuu loved and he was happy enough to have her around. Except one day, when he was supposed to be camping out with Taiju but it got rained off and he trudging in to hear Nao screaming that Byakuya wasn’t emotionally available enough and too focused on that damn kid that’s not even yours. And for the first and only time in his life, he hears Byakuya really lose his temper and yell at her to get the fuck out of my house and never come back . And he knows Byakuya doesn’t regret it but once again this stupid need ruined something good. 

People like to joke that Senkuu is “oblivious” to romance but that couldn’t be more untrue. He can detect the signs easily, despite romantics claiming it to be ineffable and defying logic there’s simple science to sex and romance that he can follow. It just doesn’t interest him. His mood is plenty high without regularly dousing his brain in unsustainable baths of oxytocin, the effort required to get an output is prohibitively inefficient and everyone else’s insistence that it defies logic makes any kind of rationalising impossible. 

So when Tsukasa hides his question behind something general and open, Senkuu isn’t “oblivious”. He hears the undertone, the need, the where do I fit in your world and it exhausts him. 

‘Isn’t that obvious?’ He quips, ducking into conversational evasive manoeuvers. This isn’t Gen, he’s probably skilled enough to de-escalate this. ‘I’m going to be an eternal astronaut. I’ll perfect Earth and then be on my way to Mars. The kingdom of science will become the first galactic empire!’ He laughs, big and cocky, and realises he’s made a mistake because he can feel his throat tremble and Tsukasa might not be Gen but his hunter’s instinct is terrifyingly sharp and he’ll hear that quiver. 

He sees it, the moment Tsukasa hears that fear. He sees Tsukasa’s eyes widen and sees him step back, retreating. Frustration, shame, the usual suspects claw their way out of Senkuu's brain, stinging his thoughts. His bluff has failed and now they’re going to be circling the mine of Tsukasa’s unanswered expectations. 

‘I mean, what did you expect?’ The rough edge in his voice is clearer now. He’s too tired to hide it. ‘I’m not the guy who’s going to pick a nice girl, get married, settle down…’ 

Tsukasa

He’d prepared himself for a lot of things. For disgust, for ignorance, for no answer at all. But he hadn’t prepared for the hurt or the fear . The brittle trust between he and Senkuu now seemed to lay shattered between them, and all Tsukasa could think about was that quiver in his voice. It was like he’d barely heard the words Senkuu had chosen over the emotion screaming beneath them. 

Please don’t do this to me! 

He ached with regret, longed to reach out and smooth past those careless words. Why had he thought he didn’t need to define things before he brought this up? He had no words to explain he wasn’t trying to ask for something you can’t give but he also didn’t clearly know what he was asking for. 

‘I’m sorry, Senku.’ 

Senku

The apology hung between them. Heavy. Sour. Useless. 

‘Don’t be, we can’t all be your type.’ The words came, fast and easy, building a wall between them as though that would protect their tentative alliance from this artillery. ‘You’ll probably marry Minami and give Mirai a little pack of nieces and nephews to dote on. They won’t believe their dad was once the scourge of the new world! This will all be a little anecdote that feels as allegorical as the Hundred Tales.’ 

‘Senku-’

‘Me, I’ve never wanted to settle down. I used to joke to Yuzuriha that if she and Taiju ever got hitched I’d ask them to keep a spare room I could crash in between missions. Childish. Obviously. They’re another pair that will have a litter to take care of.’ He forced another laugh but this time the chasm opened up. 

For now, the kingdom of science ran at his side but that wouldn’t last forever. Already, his allies were distracted by their attachments, and crushes, and after all it was science an essential part of the survival of the species and all. 

But he didn’t belong to it and he knew that once that consumed them there would be no place for him. And they couldn’t all be Byakuya, throwing every chance away to protect one small scientist who never even managed to thank the old man to his face. 

‘Senkuu!’ 

He turned away from the pity in Tsukasa’s face and for a moment he let the irrational hatred consume him. Why should Tsukasa pity him for choosing science as his deepest love? Why should Senkuu himself feel lonely? Kaseki had devoted his life to craft and was deeply happy. Byakuya wouldn’t have become an astronaut if he’d married Nao. It was the right choice . 

But the lab was so much colder and quieter when he was there alone. And it always would be. 

Tsukasa

Senkuu ran away. Not in a physical sense, he still led the kingdom of science and never questioned the place everyone has assigned Tsukasa at his side. But inside himself, the vulnerable Senkuu who sought help and leaned on Tsukasa, had vanished. Senkuu is almost too bold, too bumptious, racing towards goal after goal until Gen has a labour intervention, and then Senkuu subsides into quietly building on his own, accepting anyone who comes to his side but seeking no-one. 

Tsukasa isn’t the only one who notices. Taiju and Yuzuriha have permanent lines between their eyes these days, Kohaku tries to jolly Senkuu out of the mood, Chrome and Kaseki push their innovative powers to make him smile, Francois tries to tempt him with treats, Ryusui is casually handsy in a way that makes Tsukasa want to crush his throat and Gen hovers by him like a mother hen, tending to Senkuu's mental health as delicately as possible. But even though Tsukasa knows what he said, he can’t understand how the simple hint seems to have opened this bottomless pit in Senku. 

The man is surrounded by loving friends and allies, yet all Tsukasa can see behind his eyes is a lonely little boy, clutching his science to his chest like a teddy bear. It’s like their warmth is unable to reach Senkuu anymore, like somehow those few sentences exchanged have ripped away some essential thread. 

Senku

When Ginro, ever tactless, guffaws and asks Senkuu if someone broke his heart, something in him snaps. His grip on his cool logic slips and he finds himself acting like a meathead, screaming wrathful words into Ginro’s shocked face and stomping into the darkness with his blood burning. 

‘You’ve got to have an outlet, kiddo.’ Byakuya used to say to him, when Senkuu refused to cry after a tenth rocket failure, or carried on as normal the day after the hamster he’d raised for a research project simply stopped moving. ‘You can’t logic away your emotions. The scientific way to do this would be to find an effective way to process them so you can move on.’

But Senkuu didn’t have time for that in the Stone World and how was he supposed to deal with stupid, tiny things like the fears Tsukasa’s loaded question had stirred up when he had the black hole of Byakuya eternally trying to capture him in its gravity? 

Come back, you stupid old man. What good is Ishigami village and a thimble full of platinum when you aren’t here with me? Who’s going to watch me rebuild the world? Who’s going to eat ramen with me? Come back. Come back. 

‘COME BACK!’ For a moment, he thinks the words must have come from someone else, Suika or someone calling out after him. It seems so impossible that this logicless, pleading scream is coming from his own lips. 

Count. You can’t lose yourself. You need to know exactly where and when you are. Count. How long have you been walking? What direction? If you get lost in the wild it’s game over. Count. Count. Count. 

Instead of seconds it’s breaths he’s counting and they’re coming much too fast for safety. 

Panic attack. My brain is flooding with unnecessary adrenaline. Hyperventilation. Dangers; loss of consciousness, unsure footing, excessive energy consumption, loss of stealth. 

‘Come back.’ The plea is more of a sob now, and he can’t tell where he is or why he went there. 

Something warm and firm wraps around him, and for a moment his oxygen saturated brain makes the stupidest conclusion. 

‘Dad?’ 

Tsukasa

It’s Taiju who dares touch Senkuu when they find him in the woods, sobbing incoherently, and the one word he speaks when Taiju pulls him upright is like a sharp slap. 

It’s so stupid that he, the man who’d fought so hard for the one piece of his family remaining, hadn’t even considered how it felt for Senku, running eternally away from the truth that his father was long dead. 

He shrugs off the lionskin and drapes it over the shaking figure Taiju carries. They share a look but neither can bring themselves to speak until Senkuu is limp in Taiju’s arms. 

‘He never grieved. Did he?’ Tsukasa knows the answer, but it feels important to make the words real. 

‘I should have known. He’s always like this.’ Tears streamed down Taiju’s cheeks. ‘He was always cracking those nervous jokes about how nobody would be there for him when the old man was gone.’ 

Something in Taiju’s words jogged Tsukasa’s memory, and sickening horror finally connected his words to Senkuu's pain. He hadn’t just asked Senkuu to look at how their worlds might combine, he’d cruelly reminded him of how much sooner that loneliness of being the last of your family descended. There was no-one for Senkuu to search for, and he couldn’t see himself building a new one. 

He wished he had chosen those words more carefully. Expressed a desire to carve a place in his own world that Senkuu could always comfortably fit. Explained that he couldn’t see himself settling down with a nice girl and a pack of kids when so much of his heart wrapped around the strange, wonderful man who’d saved the world on a whim. 

‘Taiju. We shouldn’t… talk about this carelessly.’ Tsukasa hesitated, unsure how to continue.

‘Eriously-say.’ Gen, ever quick with his silver tongue, spoke up, having caught them up somewhere along the line. ‘Our sweet Senkuu is the type who compartmentalises his feelings - usually, that sort has some kind of hobby they use to escape it. If I had to guess, in the old world that was science. Now that science has become his job? Senkuu doesn’t have an outlet.’ 

Taiju was exclaiming about the genius of these words as Tsukasa mulled them over. An outlet. Those tentative requests for indulgence. His slightly spiteful humour. The way he would sometimes bundle his cover around his fist and press it close to his mouth like a child. Senkuu was looking for an outlet, and Tsukasa suspected that his hasty words had closed them off. He winced. 

‘Oh? Tsukasa? Got a little onfession-cay for us?’ Gen laughed lightly but there was a savage edge to the words. Tsukasa understood. Gen’s loyalty to Senkuu ran deep. There were plenty of people like Tsukasa, Taiju and Kohaku who could cover Senkuu's lack of physical strength, but Gen alone covered what he lacked in emotional intelligence. And Gen alone had realised how brittle Senkuu's peace truly was. 

‘I… asked him something a few weeks ago. I think he took it wrong.’ Tsukasa admitted. 

‘Oh, broaching that little ush-cray you can’t even wrap your own head around went badly, huh? Who could have seen that coming?’ Gen’s fury comes across in his uncharacteristic recklessness, usually he would never dream of provoking someone as dangerous as Tsukasa. 

‘Wait? What?’ Taiju looked between them, wide-eyed and uncomprehending.

Tsukasa has always had the instinct to put himself atop the social pyramid and it takes real effort now not to grind Gen down in retaliation. He swallows the inclination and keeps his voice measured. ‘That isn’t the right word for it. I just wanted to know where he stands.’ 

‘He stands alone, Tsukasa!’ Gen snapped. ‘And if you’d watched him half as closely as you thought you had, you’d know that!’ 

‘That’s not fair! We’re all around him!’ Taiju protested. 

‘Oh really Taiju? What about when you and Yuzuriha are on your honeymoon?’ Gen sighed. 

Taiju blushed and blustered and protested that they couldn’t know that would ever happen, but Tsukasa focused more on the mentalist.

‘How long have you known he was worried about that?’ He asked. 

Gen hid his hands in his sleeves and sighed. ‘Pretty much right away. He didn’t bat an eye at how eautiful-bay Ruri was. He wasn’t conscious around guys either. Then you think about the basic psychology of eople-pay in his position and it’s a common ear-fay.’ The pig latin was flowing thicker and faster as Gen’s nerves grew. ‘And I figured I had at east-lay a few more ears-yay with Kohaku being such a tomboy, Ryusui being so Ryusui and you being so ependably-day iligent-day!’ The double fault left Tsukasa actually having to pause to translate. 

‘You didn’t think I’d broach the topic until I knew exactly where I stood.’ He gave the words form, confirming them more for himself, but Gen agreed anyway. 

‘Exactly! I had plans . If Kohaku started thinking about that, I would have Yuzuriha and Ruri talk her through. If Ryusui tried anything it was moot, he’d blow past it so casually Senkuu wouldn’t care. But you…’ Gen shook his head. ‘I thought you’d take so much time about it, that I’d have a chance to give you both the right words.’ 

‘Give us the right words?’ Tsukasa couldn’t help bristling. 

‘Wait? Isn’t that manipulative? Gen!’ Taiju was still protesting but Gen and Tsukasa were focused only on each other. 

‘Of course. I bet you never even realised with Senkuu you need to pledge yourself to his world, not invite him into yours.’ Gen sneered. ‘And I could have warned him that he wouldn’t be able to look at letting someone in until he faced the hole Byakuya left.’ 

‘You talk like you want that spot.’ Tsukasa doesn’t believe those words, not really, but he feels wrong-footed and he needs to reclaim some ground between them. 

He sees the moment Gen too gives into rage and chooses to hit back. There’s a coldness in his eyes and a calmness to his voice as he says the words that slice cleanly into Tsukasa’s soft underbelly. ‘It’s mine if I do. I understand what he needs, and I’ve been wondering for a while if I should step in and give it since nobody else seems to.’ 

‘Can’t you tell us?’ Taiju’s words finally break through the stand off. He’s still crying, still carrying Senkuu as though he weighs nothing, and still taking no offence at their dismissing him. ‘What aren’t we doing for Senku?’ 

Gen pauses, a pained look on his face. ‘Senku… needs to be someone’s top priority, in a way that has nothing to do with his own brilliance. That’s why this whole romance thing is such a trigger topic. He doesn’t value romance or sex, so being valued for those things is worthless to him, yet he knows most people value the person who offers them that the most until they become a parent. So it doesn’t matter if you love him as much as you love Yuzuriha, Taiju, because she’s going to be able to give you something he won’t.’ Gen fidgets. ‘That’s why I think I could do it for him. We’re both self-interested enough that it isn’t a threat. And my tricks make that sort of thing less valuable to me.’

‘I don’t want that from him.’ Tsukasa spoke up, firmly reiterating. 

‘I know.’ Gen pauses. ‘But if you want that from someone, anyone, in your future… Senkuu won’t see a place there. And he’s not an easy pick you know? He’s selfish, he’s arrogant, he works people to the bone, he’s restless, he’s bad at showing that he cares…’ Gen shook his head, a worried mother hen again. 

Tsukasa paused, and pictured something a little different. Instead of a cosy home with a wife and kids, he imagined a quiet space that waited for him and Senkuu to return from their latest expedition and return it to life. He imagined evenings spent getting impromptu lectures, getting woken at night by a light form squirming away from him as a midnight idea struck, being the one who was allowed to step forward and scoop up Senkuu when he stumbled. He imagined a bond that wasn’t affirmed with a kiss or a ring, but instead a head on his shoulder, a slender figure sheltering in his warmth, a wide grinned assurance that his offhand remark about missing the taste of dark chocolate after a long day was soon to be a thing of the past, because that tempering process just so happened to be the perfect way for them to practice this oh-so-essential sanitation project. 

‘He’s perfect. Just like he is.’ Tsukasa’s voice cracked.

Senku

It had, of course, been the big oaf screaming his name that had woken him. What aren’t we doing for Senku? 

The humiliation had smothered him and Senkuu had stayed limp and quiet, silently seething and planning to take revenge on Taiju, Tsukasa and Gen for talking about him like he was a pet project. 

Then Gen’s assessment had flowed out, an unintentional tongue lashing that laid Senkuu bare. He needs to be someone’s top priority. Yuzuriha can give you love and sex. 

Hate for Gen’s mentalist mastery made Senkuu tremble then. He wanted to surge out of Taiju’s grasp, smack the smug words out of Gen’s mouth and tell him to take his pity and shove it up his arse. 

I don’t want that from him. And there was Tsukasa’s gift, sounding oh so convincing when he was stating the obvious. Nobody wanted sex or romance from Senku. It was so obviously pointless that it didn’t occur to anyone. Senkuu had never thought Tsukasa was asking to be his lover, it just seemed so stupid and pointless to ask for an escalation in a relationship with nowhere to escalate to. 

And then Gen’s at it again, rhyming off Senkuu's list of flaws, and strangely this one is a relief. Everyone seemed to need to reassure Senkuu that he could change, that he could be his scientist self and a boyfriend, husband, father. But not Gen, who so effortlessly pointed out how impossible that was. 

Senkuu braced himself to sit through Taiju’s well-intentioned, oafish rebuttal of Gen’s assessment when Tsukasa’s clear voice cut through. 

He’s perfect. Just as he is. 

Senkuu's mental map of this social interaction crashed abruptly. This wasn’t where Tsukasa was supposed to go. He was supposed to get angry at Gen for ripping open his foolish hopes, or resign himself to a happy life with Minami, or even have an epiphany that Senkuu had stirred a latent bisexuality in him and redirect his energies to a more suitable man. 

He’s perfect. Just as he is. 

What did that mean? What did Tsukasa want from him? What was he supposed to be to Tsukasa now? His friend? His rival? His crush ? 

Senkuu played possum until Taiju laid him down in the lab, and then took the excuse of the Ishigami villagers frantically (and loudly) discussing what had happened as his “wake up call”. He brushed off their concerns with a mocking comment about how even he had limits to how much Ginro he could stomach and wrangled Chrome and Kaseki and Francois into helping him refine the cacao they’d acquired in Brazil into dark chocolate, so that they could begin tempering the glass better. (And if it happened that Tsukasa had mentioned missing dark chocolate, well, Gen wasn’t the only one who could use nasty tricks to buy temporary loyalty. There was no need for Senkuu to probe himself for a deeper motive.)

Tsukasa

The chocolate was cracked just in time for Yuzuriha to give a crash course on Valentine’s Day. He cherished the family chocolate that Mirai beamingly presented him and he gently and earnestly responded when Minami used it for a push of courage. 

‘I’m sorry. I can’t accept your feelings.’

She didn’t look surprised, though tears fell from her eyes. ‘I know. But I wanted you to know… I can move on easier now.’ She smiled at him, so beautiful, and for a moment he wondered if he really wanted to walk away from that cozy life she could give him. 

And then he thought of the look on Senkuu's face, when they were out at camp and Tsukasa returned from a private relief break, the way that he half smiled and settled back to sleep, content in their proximity to one another, and he knew it would be blatant disrespect to tell Minami he could love her the way she deserved. 

And in a way, who could top the fact that Senkuu had recreated chocolate for Valentine’s Day. Just after Tsukasa had carelessly asked for it, not considering how attentive Senkuu was to the little wants of others. Tsukasa wasn’t sure if it was truly a gift for him, but he knew it would be a gift nobody else could ever top. 

Senku

Gen had started making him talk about Byakuya sometimes. It hurt, and he found himself lashing out at his friend more than once, depending on Gen’s supple strength and seemingly infinite patience when working towards a goal he wanted. 

Slowly, the black hole lost its potency. Senkuu started to be able to think about the future without Byakuya in it without feeling like he was going to fall apart. He started to be able see the traces of Byakuya’s features in the villagers without hating them for it. He stopped resenting Lillian Weinberg for doing what Nao had failed to do, stopped feeling jealous of those unmet siblings who were Byakuya’s real kids, and started to be happy that Byakuya hadn’t been alone, not even one day, until the end. 

He still felt terrified, sometimes, imagining the cold empty lab in the days when Chrome and Taiju and the others became parents and families and had to pass around odd uncle Senku, the awkwardly fitting piece that they all tolerated because he’d done so much for them. They would be kind to him. He knew that for sure. When the kingdom of science was truly a new society, he would never be left alone for Christmas or miss a New Year’s sunrise. Someone would make sure his birthday was marked, someone would drag him out to dinner a few times a month. But he would become an obligation. Someone they looked after out of gratitude and because they didn’t believe he could fulfill himself - and maybe they were right. He could see no cure to the loneliness that had been left behind when his grief for his dad had shrunk to a livable size. 

He avoided Tsukasa, pushed him to Minami as much as possible, even provided tools of rebellion to Mirai to fill up his time and his mind. He didn’t know what delusion Tsukasa had constructed to call him perfect and he didn’t want to know either. 

His shoulder throbbed, and he reflected that he really had to re-invent a self-massager. It had been stupid to dismiss it as something they could cover with social labour. It was too close, too touchy. He supposed Taiju’s oafish kindness or Francois’ unapologetic practicality would let them help him with it, but he shrank away from asking. He didn’t want their help. 

He didn’t want to miss Tsukasa’s help either. 

Tsukasa

Spring, summer and autumn slipped by, filled with new and exciting re-inventions. Lightboxes and reels made animation a mind-blowing experience for stone and old worlders alike. Spices were rediscovered, shoes improved, bicycles recreated. Colourful dyes had the young and old alike suddenly sporting heads of blue and pink and green (including a terrifying three weeks where Mirai seemed teetering on the edge of going full Gal until it became apparent she just wanted to play mermaid princess again.) 

Through it all, Tsukasa hunted for little pockets of time where he could go to Senku, help him, and protect him, but Senkuu was still hiding those gaps in his guard fiercely. Everyone else (except perhaps Gen, and weirdly Ryusui) seemed fooled by Senkuu's bright mood and the occasional admittance that he was tired and needed a break, but Tsukasa could see that Senkuu was still running away. 

Well. The thing with science is it was replicable.

Patiently. One step at a time. From the very beginning. All over again.

Making sure his strength was always available when Senkuu's arms couldn’t live up to his ideas.

Making sure that Senkuu always had enough and something good to eat. 

Dropping the lion skin, unasked, over him as the autumn winds brought the first nips of winter’s chill to their kingdom. 

Keeping watch while Gen made him talk about Byakuya and always acting as though he hadn’t heard the sobs or shouts. 

Proving himself. 

‘Yo, Tsukasa.’ It was almost a full year since that disastrous conversation, and for the first time Senkuu had called his name out loud again. ‘Christmas is coming up. You got anything special in mind for Minami?’

Tsukasa smiled. ‘Small talk, Senku? Am I dying again?’ He shook his head. ‘I’ll make a fuss for Mirai. She loves it.’ 

Senkuu paused. He avoided Tsukasa’s gaze, his voice low. ‘Come on. Every poor kid has one. What was that present she never got that proved Santa didn’t exist?’ 

‘Sorry, Senku, you can’t just re-invent this one.’ Tsukasa smiled sadly. ‘A “Disney Little Mermaid karaoke microphone”... Something completely impractical, full of copyright and all lost media.’ 

Senkuu finally looked him full in the face, eyes burning. ‘Watch me.’ 

Senku

It’s a shit karaoke machine. And he has to admit, it barely counts as Disney, let alone Little Mermaid, and it’s a one off build for the whole town so it isn’t like he can really call it Mirai’s present. But with a collection of instrument artisans, a few fans recreating classic melodies and a slight reworking of the microphones for the cellphones, he had made a karaoke house, with a stage, and invited Mirai to be the first to stand on it. 

Her little face lit up as the first few notes of “Part of your world” played and her high, quavering voice was more pleasant than not. She was met with cheers from her uninformed audience and they accepted her as their mermaid princess without question, especially as Yuzuriha had made the outfit. 

Tsukasa watched her, his eyes brimming in a way he didn't bother to hide, and Senkuu felt a rush of protectiveness that startled him a little. Him? Protect Tsukasa? Very little provided enough threat for that to be necessary. 

‘Sorry. You were right. I didn’t make it at all.” He stood close by Tsukasa’s side and watched the stage so he didn't have to look at the handsome face. 

“This is perfect. I've never seen her so happy.” Tsukasa whispered. “Thank you, Senku.”

He felt Tsukasa slide a hand over his hair, passing back and forth in an affectionate gesture that was strangely enjoyable. 

“I figured I owed it to you, since I broke your heart and all.” Senkuu chose to rip the bandaid off, deciding there was no point enjoying a closeness if it was nothing more than a misguided crush. 

“You didn't break my heart. I never wanted you to be in love with me.” Tsukasa replies simply. Words like broke your heart don't have as much impact on Tsukasa as they do on most of the others and it's both frustrating and reassuring to not be the only one unmoved by eros. 

“But you didn't get together with Minami. And you practically confessed your love for me to Gen.” Senkuu drops the bomb he's been holding for months. 

“I'm not in love with you either, but I do want to spend more time with you.” Somehow, compared to when they had this conversation last year, Senkuu doesn't think he can run away this time. Tsukasa isn't going to be thrown off by a word barrage and he isn't confused enough for Senkuu to sidestep the topic. 

“What does that mean?” Senkuu played for time. Could he provoke someone to interrupt? 

“I don't want the pack of kids thing. Or the wife thing. Eternal astronaut sounds more fun; besides, I still need to build a pure hearted Utopia.” Tsukasa’s hand rested on his shoulder and Senkuu felt something stir. A sense of belonging. 

“You could do that better without me surely. I'm on Ryusui’s side, bring back capitalism!” Senkuu's spoke fast, trying to provoke some kind of snap. 

Sure enough, Tsukasa frowned. “I'd rather do it with you. You're brilliant, and you have a knack for making people happy, and I like spending time with you more than with anyone.” Tsukasa moved, looked him directly in the eye as he talked and Senkuu's heart fluttered uncomfortably. 

“I told you before. A guy only compliments another guy to his face if he's gay or manipulative. Which is this?” Senkuu forced himself not to look away.

Tsukasa 

He knew Senkuu was challenging him more than asking a sincere question but he answered it anyway. “Maybe a little of both? I'm not exactly gay. I don't want you - or any man - to bed me. But I do want your company more than any amount of romance or sex. And I'm definitely manipulating you. I want you to choose to stay at my side, so I'm making my premise more appealing for you. I don't want someone like Gen or Ryusui to matter more to you than I do.” 

Colour stained Senkuu's cheeks and he resisted the urge to cup them in his hands. 

“You're one crazy bastard.” Senkuu forced a laugh but he looked a little scared again. “You’re not making sense. So, you want to run away to outer space with me and live like monks?”

“You'd never do that, you take responsibility for your creations. I'd get to see Mirai whenever we come back here. As for monks… well, close enough. I never did like how much attention you need to give a girl to have a love affair.” He shrugged. 

“I wouldn't be nicer to you.” Senkuu glared. “I don't care if you want to tail me like a lost puppy or what, I don't have time to pamper you.” 

“You're plenty nice to me.” Tsukasa had to laugh, gesturing around. Mirai was still living out her mermaid princess fantasy, the village now had the traditional tatami that he'd always liked and hadn't even known Senkuu had realised he mentioned it often, there was a buffet table including chocolate desserts to celebrate the occasion. “I have no complaints.”

Now Senkuu was definitely blushing and fidgeting. “I could change my mind. We're de-petrifying seven billion people. I could fall in love with one and ditch you for the pack of kids life.” 

And that was it. Tsukasa understood he'd been accepted, even if Senkuu didn't yet. He'd backed himself into empty, faulty logic that he didn't believe to try and escape the conclusion he considered inevitable. He was going to accept Tsukasa’s offer of companionship. 

Senku

Somehow, turning down Tsukasa hadn't quite worked as he'd expected. Senkuu had expected that by belittling the crush and mocking its infeasibility, Tsukasa would lose heart and back off. 

Instead, since Christmas, he'd simply taken his position at Senkuu's side as a given. He was less discreet about offering him food, favours, warmth. He was too delicate around the hot spring issue, offering to keep their bathing times separate in a way that felt like it would mean acknowledging the possibility if he accepted, so Senkuu had to laugh it off as “unnecessary in the monk life”. 

The baths became strangely fraught. Senkuu was too conscious that Tsukasa would wash his back or hair without hesitation, that he could easily ask and receive a gentle massage, that  - though allegedly undesired - his body was on display. He wanted to experiment with the limits of Tsukasa’s desire but fear of creating an expectation he couldn't fulfill held him back. 

Gen tried to probe the topic but Senkuu shut it down hard. He still bore his grudge that Gen had so casually exposed his fears to Tsukasa and Taiju. 

He also truly lacked too much time to think about it. The kingdom of science was needy and he was always fighting to fulfill those needs. In a good project, a whole week could disappear without him questioning Tsukasa’s aid and presence. 

He didn't make a fuss when they threw him a birthday party and he didn't complain when Tsukasa congratulated him with both hands ruffling his hair and a warm laugh that seemed too carefree for the once terrifying emperor of might. 

February happened to be a good time to upgrade the cooking arsenal in preparation for the spring voyages and if that happened to allow them to create cheesy shapes for the chocolate craft, well as Gen would put it, it was good for general morale. 

He built a shell mould and got Francois to lighten and sweeten the mixture and Yuzuriha to help string the chocolate shells into a necklace, but that affected Tsukasa only incidentally. After messing up her Santa wish so badly, Senkuu figured he owed Mirai and helping her make something special for her beloved brother was atonement enough. 

Tsukasa disappeared three weeks later and Senkuu realised that he'd started to get a dull ache in his stomach when the guy wasn't around. He found himself scanning the horizons with his telescope once a day and interrogating Ukyo and Kohaku and Ryusui about the weather. 

He reappeared on the thirteenth of March with burns on his hands, having developed a new ramen recipe that tasted so good that Senkuu couldn't resist seconds and thirds. 

“You usually celebrate White Day by returning gifts you know.” He snarked.

Tsukasa smiled softly. “Sorry it's a year late. Thanks for the chocolate.” 

Tsukasa 

Senkuu never did admit that he'd recreated chocolate as a Valentine’s gift for Tsukasa, just like he never did admit to Gen or Taiju that he'd heard part of that conversation in the woods. Some things would never change. 

Others did though. It had been during that Spring's voyages that Senkuu had started openly curling into Tsukasa’s side by night. It had been later that year that he started to ask once again to be massaged when his shoulders ached. It was that October, the tenth by sheer coincidence of course, that Senkuu rebuilt Foosball tables and opened the stone world's first arcade and bowling alley. 

It took three years before people started using the term “partner” to describe them, and by then Senkuu had no objections. 

It took five years for Taiju and Yuzuriha to wed and that night Senkuu trembled and dug his fingers into Tsukasa and softly pleaded for him not to leave. And Tsukasa held him tightly and promised his commitment to the galactic empire of science and felt Senkuu laugh into his shoulder. 

It was seven years when Minami married someone else and Senkuu scoffed a “good riddance” and slapped Tsukasa’s arm affectionately and demanded to be made ramen that night. 

Ten years, and Tsukasa no longer had any questions without answers. 

What is Ishigami Senkuu to Shishio Tsukasa?

Irreplaceable.