Archive of Our Own ^beta

Chapter Text

Senku first met Kohaku the way he’d met everyone else in his life: in monochrome.

That was how he first saw the new world, the statues, Tsukasa, Ishigami village, all of it. In a series of greys which he knew in theory were colourful, but had no way of comprehending as such.

Senku paid it no mind. After a lifetime of experiencing the world as such, one got used to these things. Besides, Kohaku herself was sure to be almost the same.

They reached the village without it coming up. He met Ginro and Kinro without it coming up either.

It wasn’t until Chrome showed up that it was mentioned at all.

Chrome seemed enthusiastic and, despite an apparent lack of common sense, Senku suspected that it belied a genuine intelligence to rival his own. He was happy to indulge him in a ‘sorcery battle’ or whatever, if only for the amusement.

Chrome was standing over the fire he’d created, waving his hands around it, putting on a show. The theatrics were more than over the top, but at least the other three seemed into it.

“Behold! My bad sorcery!” Chrome announced, reaching into a small pouch on his belt and pulling out some sort of powder. “Rainbow bridge! Watch as I manipulate fire!”

Senku couldn’t have seen its full effect, naturally, but he knew what it meant.

The rest of the audience wasn’t quite as intrigued as Senku though.

“What was that supposed to be?” Ginro asked, leaning against his spear. “Nothing happened.”

“What do you mean nothing happened! How about this then.”

He threw another powder on. Senku didn’t miss the way the flames turned a darker shade of grey for a moment.

“Oh,” Kohaku exclaimed. “The fire’s changing colour!”

“Yes, finally .” Chrome rolled his eyes. “At least one of you appreciates my genius.” He grinned maniacally as he pulled another grey power from his pocket. “Now behold true sorcery!”

Kohaku stayed his hand. “Chrome, you’re the only one getting the full experience.”

“Eh?”

“Or so I assume.” She paused to look over at Senku. He nodded.

Chrome huffed and pouted, but moved onto his next tricks, which notably didn’t rely on colour to be impressive.

This all made things much more interesting. Between his storehouse and colour-sight, Chrome was proving to be more useful with every second.

Leaving behind Taiju and Yuzuriha had been a tragedy not just for the loss of them as people Senku cared about, but also as his colour spotters.

Being soulmates with one another, they’d had the full spectrum at their mercy for years before the petrification, and Taiju had proven invaluable since waking up. Even before, one of the reasons he’d been so eager to keep Taiju around was for how useful a pair of colour-seeing eyes could be.

But now he had a suitable replacement.

It was easy to bring Chrome into his plans. He was excited to help, and had a personal stake in the matter. But Senku didn’t bring up his colour-sight until the following night.

“So, Chrome, you’ve met your soulmate.”

Chrome nodded. “Heck yeah.”

While Chrome was obviously eager to talk about it, Kohaku groaned. “Can we please not talk about that?”

Chrome snickered. “She thinks it’s gross that her sister’s my soulmate.”

“That Ruri person, right?”

“Yep!”

“I said please.”

That explained a lot. Chrome devoting his life to trying to save his soulmate, while not something Senku could personally relate to, was something he understood.

“Whatever we think of it, that colour-sight of yours is going to be invaluable in making antibiotics. I could get it done without your help, but it’ll make the process a lot easier.”

“Baaad!”

“If it helps Ruri…” Kohaku shook her head and sighed.

“You’re just jealous you don’t have colour-sight.” Chrome smirked.

“Seeing blue is enough.”

“Still not as good as seeing all of them.”

Kohaku rolled her eyes before turning back to Senku.

“What about you?”

Senku raised an eyebrow. “What about me?”

“Your colour. Which do you see?”

There it was. Senku had hoped the conversation might avoid this point. They would have found out eventually though, he supposed it was better to get it over with.

“I don’t see any colours. Just grey.”

Chrome and Kohaku didn’t reply immediately, but Senku could feel them staring at him. Senku wasn’t ashamed of it or anything, far from it. He was comfortable seeing in monochrome, he’d never known anything different after all. But talking about it forced him to face the consequence of not having a colour.

“Oh Senku…” Kohaku’s voice was soft with pity.

“It doesn’t necessarily mean I don’t have a soulmate,” he clarified. “Before the petrification there were people with grey eyes. It was rare, but normal. But yes, there’s always the possibility…”

The way they were looking at him made Senku’s fidgeting all that much worse. It always went this way, even when he had told Taiju.

“It doesn’t bother me,” Senku said, perhaps a little too defensively. “Soulmates are illogical and unscientific. Plenty of people never meet their soulmates, and plenty more have found that kind of connection in people who aren’t theirs.” His throat felt uncomfortably dry.

From the way that Kohaku and Chrome were looking at him, Senku didn’t think they believed him.

“Whether I have a soulmate or not, it doesn’t matter now anyway, does it? Whoever they are, they’re probably still petrified.” Senku had already had this conversation with Taiju, but it didn’t keep it from stinging. Never meeting your soulmate and not having one in the first place were two very different things.

It didn’t take long for them to change the subject. All three of them were deeply uncomfortable, and asking more questions about the way the world worked seemed a much more pleasant way to waste the rest of the evening.

Meeting Asagiri Gen for the first time had been… a strange experience, to say the least.

Aside from his bizarre hair and the crack scarring his face that marked him out from the villagers, Senku had deemed him relatively unremarkable. He only knew of Gen in passing and, while winning him over was a matter of life and death, Gen was little more than a road block.

However, as the day went on, he was surprised by just how easy it was to be around Gen. How much he enjoyed being in the man’s presence.

It was different to how he felt around Kohaku, Chrome and Suika. He enjoyed their company too, being around them was relaxing, and they were friendly and enthusiastic. Despite only knowing them for a few weeks, Senku was already confident that they would prove to be loyal allies and good friends.

But that paled in comparison to the warmth and comfort he felt just standing next to Gen. Which, of course, was disturbing: Gen was immediately untrustworthy, by all definitions he was the enemy, and yet Senku couldn’t help but feel overwhelmingly safe around him.

Senku spent as much of the day on building the generator as he did showing off. He needed to bring Gen onto their side, so he could probably justify it if he tried, but he wasn’t so stupid as to ignore the immense gratification he received at Gen’s shock and awe.

He wouldn’t figure out what was wrong with him until later that night though.

Finding anyone bleeding out on the forest floor would be distressing. But for some reason, when Senku saw Gen lying in the grass, unconscious and bloody, it struck a chord of anger in him he didn’t even know existed.

After instructing Kohaku to carry Gen back to the hut, Senku hurried ahead, trying to push these foreign emotions down to make room to perform first aid.

He was already tearing up whatever spare fabric he could find into strips when Kohaku lowered Gen onto the floor and applied pressure to the wound. When he had enough, Senku knelt down and leant over to start wrapping the makeshift bandages around the wounds.

He stopped the second his hand brushed against Gen’s torso.

As soon as he did, the grey disappeared.

Seeing colour for the first time was nothing like he’d been told it would be. People spoke of the world ‘blossoming’ into colour, of the grey leaking out of it, leaving only vibrancy behind. But for Senku, one second, he was seeing in grey, and with a flash it was all gone, leaving him dazed and staring down at Gen’s chest, slick with a mix of real and fake blood.

The colour was so vibrant it made him dizzy.

“Senku?” Kohaku said with a harsh urgency. “What’s wrong?”

Senku took a breath, blinked, and then set about his job. “Nothing. Chrome, find the poppy seeds, the big ones, and scrape out the insides.”

Chrome did as he was told but Senku took no notice. He was thankful for how surprisingly minor the wound was, most of the bright liquid soaked into Gen’s clothes appeared to be a blood substitute, and the bleeding, while not insubstantial, was manageable. Senku had him patched up in a minute or so, no stitches required, and all that was left was to finish his painkillers and clean up the mess.

Once he’d calmed down and the adrenaline had left his system, getting on with the clean-up proved to be more difficult than he thought it would be.

The world in colour was so drastically different from the world in monochrome and he found himself constantly distracted by it all.

All of his materials looked different in colour, and he would have struggled to figure out what was what if he hadn’t already had Chrome help him label everything. He looked through them, piecing together a mental map of what colour was what based on what he knew about the different minerals.

He might have asked Chrome to help if he was awake, but he’d nodded off in the corner. Then again, explaining it all would have been inconvenient, so maybe keeping this to himself for the time being would be a good idea.

This whole soulmate business was confusing after all, and Senku had been half convinced he didn’t have one for the best part of his life. He wanted to sort it out in his own head before talking to anyone else about it.

A few hours later, still unable to sleep, Senku heard shuffling. He turned around to find Gen stirring.

His breath hitched and he watched, apprehensive, waiting for Gen’s reaction. But nothing of the sort came. Gen began to mumble and Senku listened to his request and watched him. He saw Gen’s eyes, glazed over, not seeing anything, and Senku let out a breath he didn’t know he’d been holding.

He agreed to Gen’s request. For something as small as cola, Senku wouldn’t have dreamed of refusing him. At that point, Senku wasn’t sure he’d be willing to refuse Gen anything, and he still didn’t know what to make of that.

Gen shortly drifted off again and it wasn’t long before Senku found himself succumbing to sleep too.

When he woke up to find Gen gone, he wasn’t surprised. They all knew that if Gen didn’t get back to the Kingdom of Might soon, they’d all be doomed.

Senku may not have been surprised but he was disappointed. He supposed their conversation would have to wait until the next time they met, whenever that would be.

Chapter Text

Keeping his colour-sight from Chrome and Kohaku didn’t prove to be too difficult. Without the help and guides people were normally afforded after finding their soulmate, Senku continued to struggle with colours for a while, figuring out what was what, even if he knew it all in theory. So, he was confident that, at least for now, he wouldn’t have to worry about them finding out.

They made steady progress with the sulpha drugs and it felt like the grand bout was upon them before they knew it. The entire event proved unpredictable, but nothing quite so much as their surprise guest in the middle of it.

Senku could feel Gen’s presence before he saw him. That strange, still foreign feeling of security washed over him, despite their dire situation, and he wasn’t particularly surprised to find Gen stood behind him.

But there was no time to address any of this, yet again. After the bout they had to rush with the antibiotics and then his revelation about Byakuya and then Hyoga. It was a long time before Senku so much as considered what he should do about his soulmate situation.

In theory, Senku knew he should bring it up quickly, and that would be easier than ever with Gen’s permanent addition to the Kingdom of Science. But, as he was seeing again and again, what should work in theory didn’t always pan out quite right in reality.

At first, he couldn’t find it in himself to confront something so emotional while still dealing with his lingering grief. But even after he’d reached peace, he couldn’t find the time to bring it up.

He spent a lot of time with Gen, who always seemed to be hanging around, both when Senku demanded his help and when he didn’t. He didn’t complain, having Gen around felt… right. It upped his productivity too, which was an unforeseen blessing. Focusing was easier, his thoughts were more fluid and cohesive, and his hands seemed to be steadier.

As much as he grew used to Gen’s presence though, as comfortable as Senku felt around him, he just couldn’t find the right time to bring it up.

Gen saw colour and he didn’t try to hide it. But even with it being such an open topic, Senku struggled to bring it up, especially in private. He’d avoided so much as thinking about soulmates in the past, to the point where he knew shockingly little about them, and it wasn’t a habit that was quite so easily broken, it would seem.

The worst part of it all however, was that Gen showed no signs of bringing it up himself. Which was beyond frustrating, Senku knew Gen didn’t have a problem with addressing difficult subjects, as tactful as he usually was.

The months flew by without a word about soulmates passing either of their lips and after a while, Senku figured that if Gen didn’t want to talk about it then maybe they didn’t need to. They were growing closer in spite of it after all.

And then his birthday came.

Senku was still in disbelief after everyone had left for the night. Well, almost everyone. Senku fiddled with the telescope, getting used to its limits, as Gen stood to the side and watched long after their conversation had died out. The lengths to which Gen had gone to figure out when his birthday was were, logically, obvious; of course someone would do that for their soulmate, Senku knew he’d do it for Gen if given the opportunity. But it felt different being on the receiving end, it was strange to think that Senku had someone in his life doing this sort of thing for him.

“Hey, Senku-chan.”

Senku was broken from his thoughts and looked up at Gen.

“Hmm?”

“You know, I never realised that the night sky was blue, and not black.”

Senku looked up at the sky in turn, at the expanse of deep blue peppered with bright stars.

“Yeah,” Senku replied. “It’s the same as the sky in the day; the light from the moon appears as blue the same way sunlight does, y’know, because of refraction and all that. I mean, it's all sunlight, but that's beside the point. Light pollution stopped us from seeing the sky as it should be though, and not only in cities like Tokyo.”

Gen nodded but Senku missed his small sigh. “I was vaguely aware of that. I’ve never really seen the stars like this before.”

Senku nodded. “Yeah, it was a pretty big problem actually. Astronomers couldn’t operate well in highly populated areas. Chile was the most popular relocation, much of what we learnt about space in the modern age was discovered there. Though it is a bigger issue than that, light pollution has been proven to cause severe health problems in people, including increasing the likelihood of insomnia, depression and obesity.”

“And yet you’ve just introduced artificial light into the stone age.” Gen’s words were teasing but there was no bite behind them.

“It should be alright for now. We aren’t using blue light, and the villagers all sleep and rise with the sun as it is.”

It wasn’t until the following morning that Senku realised what Gen had been trying to do, and that he’d subsequently turned it into a lecture.

He felt like an idiot, but it was comforting too. At least he knew Gen was interested in talking about it.

It was only a matter of time, he assured himself, and got on with his work.

As it usually did, life continued to get in the way of the much-anticipated soulmate conversation. It wasn’t long before they were embroiled in war with Tsukasa, and when the lives of the entire village rested on Senku’s shoulders, devoting brain power to anything other than the war effort was out of the question.

But eventually, everything calmed down.

The war was over, Tsukasa was gone for the time being and Senku was back to reviving the world, and he suddenly had all the time he needed to do it.

Senku was particularly glad for their increase in population, the more hands for the labour effort the better. More than that though, Senku was relieved to have Taiju and Yuzuriha back. And, while it may have been a little selfish, it was in large part because he knew that they would be able to help him with the soulmate situation.

Taiju and Yuzuriha had known they were soulmates for years, so he thought that Yuzuriha at least would have some useful advice. Besides there were few people he trusted as much as he did them.

The issue came up sooner than Senku was quite prepared for, however.

As the new leader of almost a hundred additional people, Senku knew early on that he would need to figure out how best to handle them all. And knowing what he was dealing with was imperative. Of course, that was one of the many reasons having Gen around was so beneficial, but there was only so much he could help with. By this point he’d been a part of the village longer than he’d been with Tsukasa which meant that he didn’t know half of their new citizens.

Hence, Senku turned to Yuzuriha.

She proved herself to be very knowledgeable about everyone, in spite of having been an openly suspected spy. Then again, while she’d never been particularly proud of it, Yuzuriha had always been good at gathering gossip, not that she was one to spread it.

One conversation later and Senku knew about everyone’s skill levels and strengths, he knew how much they ate and what times they tended to sleep. He knew about the cliques, who clashed with who and he had a vague idea of the few couples that had spawned. He even knew who was afraid of spiders and who was scared of thunder.

“Hiro was always talking about reviving his brother, he’d tell Tsukasa that he was on the baseball team and would make a good addition.” Yuzuriha was making her way through significant familial connections, which Senku figured he could use as good points of bribery. “Although I once heard him talking about his parents as well. That was quite normal actually, a lot of people seemed to disagree with Tsukasa when it came to smashing their parents. Not that anyone told him.”

“Sounds about right.” Senku nodded and looked over at the large congregations of people just beyond where he and Yuzuriha were talking. “People are fine to talk with complete logic until it becomes personal.”

“Yeah, although not everyone was like that. There are some people without parental figures at all. Anri in particular seemed to have a terrible relationship with her parents. She was more concerned with bringing her boyfriend back, although we haven’t found him yet.”

“Her soulmate?”

Yuzuriha shook her head. “She doesn’t see colour, as far as I can tell. Although it’s not unusual, as you’re all too happy to remind me.”

Senku snickered. He hadn’t told Yuzuriha about Gen yet but he could imagine she’d be saying a lot of ‘I told you so.’

“Actually, that’s a point,” Senku said, changing the subject. “Is there anyone who can see colour?”

“A few.” Yuzuriha scrunched her brow in thought. “I’ve had to pick up on that myself mostly. Unsurprisingly, everyone that I know has a soulmate seems reluctant to talk about it. I know I would be.” She looked down at her hands. “I can’t imagine not having Taiju with me, I’m just glad that he had you when I was still petrified.”

She paused for a moment before beginning her list.

“I know Nami sees colour, as does Chika. They’re pretty good friends and I wouldn’t be surprised if their soulmates didn’t play a part in it. Hideo definitely has a soulmate; he’s told me about her. And I think Yuji does. He’s a pretty private guy in the first place but I know he at least sees colour…” Yuzuriha trailed off as she continued to think about it. “I think that’s it. I can’t think of anyone else… oh, and obviously there’s Gen, but you already knew that.”

Senku did know that.

“I think I read about it in a magazine once. But it was easy to tell he could see colour from the day he woke up anyway. He’s not exactly quiet about it.”

Senku didn’t know that.

“Wait, what?” he said, voice loud and panicked.

Yuzuriha was more than a little startled by his reaction. “Uh, well, yeah. I thought you would have noticed. Gen even picked out his clothes based on colour, and no one else was particularly fussed about that. Why? Is that a problem?”

Senku couldn’t find the words to answer that. The realisation had hit him so hard and fast that he almost felt like it had punched a hole clean through his midriff. Yuzuriha had known Gen longer than Senku had, and if she’d read about it…

It hadn’t been something Senku had considered before but… was he not Gen’s soulmate?

“S-Senku!” Yuzuriha was fretting now, waving her hand in front of his face. “What’s wrong? Are you feeling sick? Should I get you a drink?”

He blinked and swallowed before shaking his head. “No, I’m fine I just…” He swallowed again and it felt like trying to swallow hair. He thought was going to vomit. “Something just occurred to me. I need to go.” He got to his feet and began to leave, but Yuzuriha followed him.

“Are you sure? You really don’t look well.”

“It’s alright,” he insisted, pausing to turn to her and force a smile. “I just forgot to do something important. I need to sort it out, so we’ll need to finish this conversation later.”

That successfully shook her off and he retreated until he was finally alone. Right then, he was very glad he didn’t have the hut to go back to, risking running into Chrome or, God forbid, Gen was not something he needed right then.

Senku spent the rest of the day holed up. Everyone was definitely worried about him; enough people came to check up on him, including Yuzuriha twice. Eventually he manufactured something to do as an excuse but made next to no progress.

He stayed stuck in his thoughts until the sun set and after he went to bed, he spent hours staring blankly at the ceiling.

It was worrying, feeling so much all at once. Senku was no robot, he had a lot of feelings all the time, but never had he let emotions so thoroughly render him useless. He was back to work as usual the following day, he didn’t have the luxury of moping when there was work to be done after all.

But still, it couldn’t stop the thought from following him like a shadow.

Chapter Text

Red wasn’t an overly common colour in nature. Gen knew that but it had never struck him so hard as it did when he woke up in the stone world.

When he’d awoken from the petrification, dazed and confused, the world around him was largely dull and grey. He knew in the back of his mind that it was a lush, bright world full of the blues and greens of nature, the gentle yellow glow of the sun, but he couldn’t see any of it.

Red signalled danger. Red, the colour of blood, indicated that something was wrong. Animals ran away from the colour red, evolved red skin or fur to scare off predators.

Again, Gen knew this but didn’t fully understand it until he woke up in the stone world. He hadn’t understood it until Tsukasa had greeted him after waking up. With his piercing red eyes, his clothing that may as well have been dipped in the blood he stained his hands with, Tsukasa was the very picture of danger.

Still, Gen loved the colour red. It was the only colour he saw after all.

Not that he let anyone know.

In the world of show business, personal information like your soulmate colour was the sort that you kept close to your chest. Gen had always found it easier to skirt those questions by pretending he already saw colour, something made that much easier by his seeing red. After all, how many people had red eyes?

Gen let this habit follow him into the Kingdom of Might.

When Yuzuriha had pulled him aside to sort out his clothing, he’d picked through the fabrics with deliberation. Most were plain grey, but others had splashes of colour to them. Some were red or pink, but others orange and purple, of which Gen could only determine from the way the red intermingled with the grey. If he tried hard enough, he could sometimes identify brown. It was something he’d grown good at. 

Gen picked up a cloth of grey with an undertone of red that ultimately felt cold.

“I’ve always been told I look good in purple,” he said to Yuzuriha as he gave it to her to use. “My costume designers liked to slip it in whenever they could.”

He didn’t miss the way her eyes widened before her expression painted over with recognition and, oddly, a little sadness. She held the cloth up to him and nodded. “I think I see what they mean. We’ll use this then.”

Gen narrowed his eyes slightly and continued to watch her for a moment, confused by her reaction. Why should Yuzuriha have any stake in his colour-sight? Or lack thereof as it were.

It was a question that ultimately went unanswered but Gen paid it little mind. It may have been strange, but as long as he banked it for later, he figured it was nothing to worry about. Especially considering how much he had that did warrant worrying about.

Gen had been awake for less than a week when Tsukasa asked him to leave. He supposed he should be thankful Tsukasa allowed him that much time to adjust considering how eager he was to hear Gen’s results. The desperation in Tsukasa’s words was so subtle any normal person would have missed it. But Gen was the king of subtlety.

He agreed, trying not to let Tsukasa know just how much he didn’t want to go on what was surely a wild goose chase. How could someone not be sure whether or not they’d killed a person with their bare hands? Gen didn’t know but he didn’t ask, and in due time made his way out into the forest.

He stopped on the way, past the miracle cave. He paused in front of the tree his target had engraved the date on.

It was strange, looking at the crudely drawn numbers and kanji. As he ran his hand over them, he got a strange feeling of wonder and comfort from it. It was the same when Tsukasa showed him the structures this person left behind. Inside, while the place looked like it had been ransacked, Gen couldn’t help but feel… peaceful.

It was a very new, very strange experience.

And maybe that was the reason Gen didn’t demand an escort, why he wanted to go alone. Why he hoped that this strange, incredible person maybe wasn’t as dead as he should be. Just so he could meet him. Just once.

He understood it all once he reached the village. He received every answer could have wanted when the strange young man, who was miraculously not dead, turned around and Gen was met by a pair of startlingly red eyes.

Senku wasn’t the first person with red eyes Gen had met, obviously. Gen remembered the first time he’d met Tsukasa, back before the petrification. When they’d met backstage, and Gen had seen that Tsukasa had red eyes, he’d been giddy with excitement, excitement that was crushed when he patted Tsukasa’s arm and was met with the same grey world he was used to.

This time though, when he looked at Senku, Gen couldn’t imagine his soulmate being anyone else.

Being in his presence felt just like running his hands over those numbers, only a hundred times more.

However, as much as Gen’s world stopped, the rest of the world carried on. The people around him continued with business as usual, which seemed to include threatening him and working him to the bone.

After thinking about it, Gen wasn’t surprised. If Senku was his soulmate, he wouldn’t see colours at all. It was something Gen had always regretted, not that he had control over it. But it was only natural Senku wouldn’t see that anything was out of the ordinary, aside from there being a spy in their midst, and would get on with life until they made skin contact.

Making that happen… was easier said than done.

Gen had known his whole life that he’d know his soulmate on sight, or that he’d be more likely to anyway. With such a unique colour, he knew he wouldn’t have to go around randomly shaking hands with people, as was the custom in the modern world, as it had been for centuries. Unlike everyone else, making contact with people wasn’t a habit he’d developed, and as the day passed Gen couldn’t for the life of him find a way to manufacture a way to touch Senku without raising suspicion.

Senku was constantly protected by Kohaku the guard dog; if Gen so much as looked at Senku in a way she didn’t like, she’d be reaching for her knife. And Senku seemed to be as uninclined to touch people as Gen himself.

At the very least, he could see that he had the same effect on Senku that Senku had on him.

There just seemed to be some kind of gravitational force between them. Senku always stood slightly closer to him than you should a spy. He spent the whole time showing off everything he’d made, which was admittedly excusable by virtue of how important Gen knew his alliance would be. What was less excusable was the look of pure joy that crossed Senku’s face when Gen gave the appropriate reactions.

It was cute.

He may have been jumping to conclusions about it all, but Gen couldn’t remember feeling so at ease, not even back in the old world.

Being attacked was a painful and fuzzy experience.

Gen remembered so little of it from the moment he was beaten bloody to the moment he woke up in the dark hut covered in bandages.

He opened his eyes and saw nothing but blurry darkness. He could tell there was a faint light somewhere but his vision refused to focus.

Despite his lack of awareness, he could at the very least sense Senku behind him. The warmth that seemed to radiate off of him was hot on his back and made everything feel just a little less awful. When they spoke and Senku leant in so close they almost touched, Gen wished he didn’t have to leave. That he could stay and bask in the feeling forever, whether Senku turned out to be his soulmate or not.

It wasn’t too much later, once he knew he was the only one left awake, that Gen hauled himself to his feet and scrambled about, struggling to pull his clothes on. He felt his way down the ladder in the dark, cloudy night, and began his race back to Tsukasa.

He didn’t know how long he rushed past dark trees and around the shadows of plants, but what felt like hours later his legs finally gave out and he stumbled, falling to the ground as his foot caught on a tree root.

Gen lay in the grass for a moment, catching his breath and wishing he were still back in the hut with Senku. He was so much colder now. He had never realised just how cold it normally was.

He forced himself back to his feet, determined to make it before Tsukasa grew suspicious. He brushed himself off and looked up to the canopy of leaves above him, where the first rays of sunlight were peeking through.

That was when he noticed it.

The colour.

The leaves above him were bright in a way he’d never experienced before. He looked down to the grass below him, shining wet with the morning dew, glowing with the same brightness of the leaves. He guessed that was green.

He looked around him, at the bark of the trees, the different hues of the wildflowers around his feet, at his own clothes.

How had he only noticed this now?

Senku must have touched him while he was unconscious. It only made sense, who else would have bandaged him up and slathered him in medicinal herbs?

Gen turned around, back to where he knew the village was. He had half a mind to go back and confirm it, but he wasn’t quite that selfish.

He sighed and continued on, picking up the pace. He’d just have to talk to Senku about it the next time they met, whenever that would be. None of it would be much good if his soulmate died before they had the chance to do anything.

He chuckled as he ran, seeing the expanse of blue (or so he assumed) above him as the trees opened up. At the very least he wouldn’t have to pretend to see colours anymore.

Whatever Gen had been expecting when he returned to the village months later, he was not prepared for what had met him.

He hadn’t been prepared to return in the middle of some kind of tournament, let alone to help with it. He hadn’t been prepared to be dragged into a race to make antibiotics either. But more than that, he hadn’t expected to return, only to find that Senku still didn’t see colour.

As he watched Senku and Chrome rush about the lab, throwing chemicals with impossibly long names together inside various pieces of glassware, the last thing Gen had expected was for Senku to turn to Chrome and ask if what he was holding had changed colour.

Gen continued to watch and every time Senku asked the same question again and again, he could feel the ground rapidly falling away beneath his feet.

Even cola couldn’t stop the painful empty feeling that continued to slosh about in his stomach. He sat in the lab alone, tracing his finger around the rim of the half-empty glass bottle and stared blankly at the contents.

He’d never heard of a one-sided soulmate bond before.

Gen knew a lot about soulmates, it was a bit of an occupational hazard. He’d done his fair share of research into the topic and not once had he come across a case of one person gaining colour-sight and the other not. It seemed cruel that he would be the one anomaly, having always been so confident in his own soulmate bond.

But again, time marched on, as it was wont to do. Gen didn’t have time to sit around crying or whatever, they were all in imminent danger.

The danger did come, and it came fast. Within two days the village had been razed to the ground and they were preparing for war.

And Gen was stuck in the Kingdom of Science.

With Senku.

It was funny how the very scenario he’d been anxiously waiting months for now managed to make him feel nauseous.

Despite that, he settled in quickly. The villagers seemed eager to welcome him, the man who betrayed the enemy for their sakes. Put like that, Gen came across as almost heroic rather than self-serving. Kaseki in particular took a shine to him, something Gen himself barely understood. However bizarre, it was a blessing in disguise as it led to a lot of time spent carrying out mindless, monotonous tasks to aid with Kaseki’s crafting. And that was time that Gen spent thinking, mostly about soulmates.

Because, the more he thought about it, the less it made sense.

Of course, the majority of people throughout history never met their soulmate in time, half of them gaining colour only upon the other half’s death. But the idea of someone with a one-way soulmate bond was in itself a logical fallacy. Soulmate bonds exist for the purpose of identifying two people who are compatible in every way; for a bond to be one-sided defeats the point.

Therefore, once Gen had finished wallowing and got over himself, he realised that, if he took this all as fact, which it was, then Senku had to see colour.

Which would mean he was faking it. It wasn’t unbelievable, Gen himself had been doing the reverse for years. The very thought lifted a weight from Gen’s shoulders.

But it begged the question: why? The only reason would be to stop the villagers from knowing he had colour-vision. But why couldn’t they know? From what Gen could tell, most of the village adored Senku, they trusted him and his knowledge with their lives. At the very least they had all agreed to go to war for his sake.

At first, Gen had guessed that in itself may have been the problem. Senku was confident to a fault, or at least his persona was, and was viewed as an unshakable pillar by his allies. From his first impression, Gen wouldn’t have been surprised to find out that Senku was hiding all signs of weakness from the villagers.

After a while that idea broke down though. Senku freely admitted to his own shortcomings and errors. And besides, seeing colour could only benefit his image. As far as Gen could tell, the gift of colour-sight was as desirable in Ishigami Village as it had been in the old world. Not to mention, having to ask for Chrome’s help when he didn’t need it seemed inconvenient and illogical.

What, then, could cause Senku to prefer such inconvenience over just telling them the truth?

Gen’s answer came mainly through getting to know Senku.

When the idea of being around him stopped making Gen queasy, he quickly found himself spending every spare moment he had in Senku’s company. He enjoyed talking with Senku beyond the fuzzy feelings his mere presence elicited. He was funny and intelligent and a challenging conversation partner, Senku seemed to play off of Gen in a way no one else ever had. And he was kind and brave and brilliant; his ambitions were so impossibly high that they literally involved space travel.

All of this, however, was hidden under a layer of social awkwardness that Gen admittedly found endearing. Senku was the type to avoid conversations he didn’t want to have if they weren’t necessary, he didn’t like to overcomplicate things outside of the lab.

And this, for the most part, seemed to explain everything: Senku, having probably told Kohaku and Chrome about not being able to see any colours, didn’t feel like explaining why he could suddenly see all of them. And so pretended he couldn’t.

Gen would have called it adorable if it wasn’t downright infuriating.

It made trying to broach the subject of soulmates that much more difficult, and Senku seemed uninclined to bring it up himself for likely the same reason.

And so, months passed without the chance arising.

When Gen began planning for Senku’s birthday, he decided that he would do what he could to bring it up then, if at no other point. It was a special day anyway, and maybe the gesture would soften Senku enough to lower his barriers.

What Gen had not been prepared for was his attempt flying right over Senku’s head. If anything, Gen cursed himself for not predicting it. Of course Senku would misinterpret what he was going for, especially when his guard was down.

Gen couldn’t hold it against him, it was one of the many things he had grown to love about Senku.

But he began to worry that it would get to the point where they simply didn’t bring it up. Ever. Gen supposed he could deal with that, their relationship didn’t seem to suffer in spite of it after all, quite the opposite.

Or so he’d thought.

After the war was over and everything was calming down, Gen had thought everything would return back to normal. That he’d go back to trailing behind Senku, watching the Kingdom of Science get on with its work, albeit with a little more manpower.

That didn’t happen at all though.

Gen couldn’t fathom why, but Senku stopped approaching him. If anything, he appeared to be avoiding him.

Which would have been bad enough on its own, but Senku, despite being overtly uncomfortable around him, seemed perfectly content to take advantage of Gen’s assistance when necessary.

It left Gen with the distinct feeling of being used.

In spite of that, months of built-up trust wouldn’t crumble in a week, and Gen decided that he would trust Senku to sort it out on his own. If Senku wasn’t going to tell him what was going on, and refuse to be around for Gen to observe, then there was little he could do about it.

Senku just needed space. They’d been inseparable for so long that it only made sense. It was healthy.

At least, so Gen told himself.

And then Senku left for Hakone again, with no plan to return any time soon and no indication that he wanted Gen to come with.

Gen didn’t want any part in the hot air balloon, as far as he was concerned that thing was a death trap, master pilot or not. But as he watched it rise into the sky, the three boys waving down at everyone else from above, Gen thought that he might have been willing to brave it after all.

He hung around longer than anyone else, who eventually all got back to work. Surviving wasn’t lazy business after all. But Gen watched the balloon as it faded to a speck and was lost behind the horizon.

It was a while before Gen could drag himself away and find something to do. No matter what he did though, and no matter how many people he was doing it with, he had never felt quite so alone as he did then.

Chapter Text

Leaving Gen behind without so much as a goodbye wasn’t the smartest thing Senku had ever done. Then again, he hadn’t really been thinking at the time.

It was growing into a bigger and bigger problem, how much Senku was allowing his emotions to control what he was doing. When he had the lives of almost a hundred and fifty people relying on his actions, it was inexcusable that he was letting his personal issues get in the way.

It was important that Senku sorted it out and, at the time, getting some distance felt like a good step towards doing that. But, if he was completely honest with himself, fifty miles was probably a little too much distance.

What was done was done though, and if he looked on the bright side, Senku figured that it would give him more than enough time to calmly think it all over. It surely wouldn’t take that long to come to terms with it all.

Senku did think it over and managed to come to exactly one conclusion: he was devastated and wouldn’t be bouncing back any time soon.

Even now that he was alone, even after weeks passed without having to contend with Gen’s presence, the grief seemed to taint every aspect of his day-to-day life. It occupied all of his free thoughts and affected his mood significantly. Everyone but Ryusui noticed, but Ryusui had no other baseline.

Senku spent much of his nights staring blankly at the ceiling of the hut, trying to convince himself of how pointless it all was and how much easier it would be if he just let it go. But he couldn’t. It seemed that being able to admit how much it hurt didn’t make it hurt any less.

It was all so infuriating. He’d been told that soulmates were one of the simplest facts of life, so then why did his have to be so complicated?

And then Ryusui had demanded they revive François. If Senku had known about the caveat, he may never have agreed.

Seeing Gen after so long simultaneously felt like a breath of fresh air and as if his lungs had been ripped from his chest.

He’d missed Gen, that much was obvious, and just seeing that he was okay flooded him with an overwhelming relief. Which instantly morphed into overwhelming guilt. Senku managed through perhaps five minutes of it before he retreated, eager to show François the new oven he’d built. Anything to distract himself.

Being around Gen in the long term proved more painful than Senku had ever anticipated.

If it hurt to think about not being Gen’s soulmate, putting up with every fibre of his being telling him the contrary was so, so much worse. Every pull to stand by his side reminded Senku that he was stealing a place meant for someone else. Every time Gen approached and he felt that same familiar warmth embrace him, he was crushed by the guilt of knowing that it wasn’t a warmth he had a right to feel.

The cherry on top, however, was how much it was hurting Gen.

Senku wasn’t blind, he noticed the looks of confusion and betrayal that crossed Gen’s face every time he left in a hurry or went out of his way to avoid his company. He hated having to inflict it on Gen, but he couldn’t help but feel that it was preferable to the disgust and discomfort he’d have to deal with if he told the truth.

He had to do it eventually, Senku knew that, but as it stood it was too soon. At least this way it was all on his own terms.

And then it seemed like Gen had had enough. Senku no longer had to go out of his way, Gen started doing it for him. He stopped hanging around, or volunteering to work in Senku’s teams, or even just saying hello in passing. Then again, why bother if he’d be ignored either way.

Senku was completely right. It was much worse.

There was a voice in the back of his mind that said things would at least be better if he’d just tell Gen why all of this was happening, but if Senku knew anything about himself it was that he was stubborn.

And so, things continued.

They returned to Tokyo once they’d found the oil.

Building a boat would be easier with more hands after all, and it felt wrong to make Kaseki make the trip to Hakone as often as he had been.

Not to mention, more people meant less time alone with Gen.

He hadn’t had a lot of that recently, but more people lead to Senku being less in his presence than ever. At the very least if Gen was occupied by other people’s company, it didn’t feel like he was being ignored.

It didn’t take Kaseki very long to figure out that something was up with Senku, although Chrome likely had something to do with that. Everyone at Ishigami Village knew there was something wrong and they didn’t seem to be capable of hiding it. Not that any of them said anything.

No one else, however, had caught on yet. It was pleasant, really, not having people look at him with concern and confusion.

And so, when Senku inevitably had to catch up with his social obligations, when Yuzuriha had demanded he sit with her for dinner, it had been a lot more enjoyable than anything had been in a while.

The company was… unusual. It seemed that Yuzuriha had become fast friends with Minami after the spy problem had blown over and she had joined them at one point, accompanied by Nikki. As had Chrome who, in the absence of Ruri, had defaulted to sitting with Senku.

The conversation was light but enjoyable. Nobody was throwing him strange looks, including Chrome who was too engrossed in most of the chatter to be focused on Senku’s behaviour. It was vaguely amusing, seeing the girls’ reactions to Chrome’s unexpected knowledge of natural cosmetics and herbal treatments.

“Wait, so you make scented soaps?” Minami had become incredibly interested when Chrome brought up that he made various hygiene and cosmetic items for the girls around the village, although mainly for Ruri.

He nodded. “Yeah, it’s easy. Just mix animal fat with wood ash to get soap and throw in some plants to make it smell good.”

“Ash?” Nikki wrinkled her nose. “Wouldn’t the soap come out all muddy and gross?”

“Maybe if you didn’t make it correctly,” Yuzuriha said. As a crafter herself she was well versed in this kind of thing. Although Chrome had the edge in crafting from raw ingredients. “But it was a common enough way of making homemade soaps in the modern era too. You could always add colourings though. Then it’ll look a lot more uniform, even to people who can’t see that colour.”

Chrome frowned. “I wouldn’t give Ruri something grey and gross, even if it is good enough for the rest of the village. She likes blue and purple so I usually go with those.”

The three girls didn’t answer that immediately, blinking at him owlishly.

Under their intense stares Chrome shrivelled a little and began scrambling for explanations. “Well, y’know… There’s this plant, with blue flowers, and if you take the roots and crush ‘em up they turn red. But add them to the soap in a bit of oil and it goes blue. Senku explained it to me once,” he said, eyes darting to Senku for back up. “Right?”

Senku nodded, choosing to ignore Chrome’s gross misinterpretation of the situation. “Yeah, alkanet root. It reacts to the alkaline of the soap. It’s not native to Japan, but I daresay it leaked out of a greenhouse or something.”

“No, no, that’s not the important bit,” Minami interrupted. “Since when can you see colour?”

Chrome was taken aback. “Since always.”

“Are you serious?”

“Why don’t we know about this?”

Yuzuriha smiled. “I assume it’s Ruri.” It was more of a statement than a question.

“Yeah!” Chrome was enthusiastic as ever to talk about Ruri. “We’ve known since we were kids. I honestly don’t remember ever not seeing colour, but I guess my colour would have been blue.”

“That’s actually kind of romantic,” Nikki said. “I’ve read books about bonds like that. To think you of all people would get a soulmate that way.”

“Hey, what’s that supposed to mean?”

“Actually, I think for the villagers it must be the most common soulmate story,” Yuzuriha pointed out, ignoring Chrome’s protest. “Everyone knows everyone since birth after all, right?” She looked back to Chrome for affirmation.

He nodded. “Yeah, I guess. I’ve heard a few of the old stories and they’re the same as us. Although I don’t know anyone else with a soulmate. Until I met you I didn’t, anyway. It’s mainly the old guys that see colour, not that we really know why. We don't know much about soulmates at all.”

“That’s true of most modern people too,” Minami said.

“So, you don’t know why either?”

“Oh no, we know that,” Nikki said. “You get your colours either when you meet your soulmate or they die.”

Chrome blanched. “Seriously? Why? That’s awful!”

She shrugged. “No clue. Like Minami said, soulmates are largely a mystery to modern people too.”

“So, you know more about space than you do about people?” Chrome crossed his arms and sat back. “That’s just weird.”

“I mean, you’re not wrong. It is a little strange,” Yuzuriha agreed. “Is there a reason for that?”

Having asked that, she and the other three all looked to Senku for an answer, who until that point had been resolutely silent. He sighed and tried to force the tension out of his shoulders. “Soulmates aren’t quantifiable the way other things like the stars and particles are. We know more about space than we do about the ocean, which is way closer to home. And again, that’s just because it’s easier. Deep-sea exploration is way more dangerous than space travel.”

“Okay, well while that’s seriously bad, I don’t see how that relates here. People are easy enough to access.”

Senku rolled his eyes. “Are you really suggesting that we should have conducted extensive human experimentation to learn more about how soulmates work?”

“We did do that, though,” Minami interrupted. “Even I know that people have been trying to figure this stuff out since ancient times.”

“But we can’t take any of it as scientific fact,” Senku scoffed. “Science is about reproducibility, and we’re not allowed to try reproducing that stuff. That’s why the study of soulmates is lumped in with psychology and the other soft sciences. It’s all theories and speculation.”

That seemed to have shut down the argument for a moment and Senku finally relaxed, thinking maybe the conversation would finally move on from soulmates.

He relaxed too soon.

“Well, if it’s a psychology thing,” Nikki said, “Gen might know more about it.”

Minami sat up and clapped. “Oh yeah, I forgot! He’s, like, an expert on soulmates. I’ll call him over.”

Both Senku and Chrome moved to shut her down.

“Don’t do that.”

“Yeah, it’s alright. It’s not a big problem, I’ll live not knowing.”

“Nonsense,” Minami shot them both down. “I want to know, too. Hey! Gen!”

The damage was done. From across the crowd of people, Gen looked up and saw Minami hailing him over.

Senku seriously considered just getting up and leaving. It certainly looked like Chrome wanted to. It was almost annoying that Chrome didn’t try harder to stop it from happening, but doing so would raise questions, and he at least had enough tact not to shove Senku into the spotlight.

Not that he had to worry about that, because Senku already knew Yuzuriha was suspicious of him. The only person who had known him longer than her was Taiju, and it was obvious that she’d noticed Senku had changed in a way bigger than you’d expect from spending a year apart. And this was even before his funk. If he hurriedly left in the middle of a conversation about soulmates it would be as good telling her outright.

So, he grit his teeth as Gen approached to talk to Minami.

“How can I help you, Minami-chan?”

It had been days since Senku had so much as heard Gen’s voice. He grimaced but otherwise remained silent.

“Oh, we just had a question!”

He nodded and looked at their group. When Senku briefly met his gaze, Gen’s entire demeanour soured and, at least to Senku, his smile became noticeably more forced.

“What did you want to ask?”

Minami, it seemed, was completely oblivious to Gen’s change in mood.

“Well, we were talking about soulmates and-”

“Wait, seriously ?” Gen interrupted, suddenly flustered.

“Yes, because Chrome here neglected to tell us he saw colours before today.” It seemed she wouldn’t be letting that go any time soon, ignoring the fact that Chrome had been fifty miles away for months at this point. “Anyway, I know you know a lot about soulmates so tell me, why do people get to see colour when their soulmate dies? And while we’re at it how do we even know that’s why?” It would seem a reporter’s instinct for questioning never died.

Gen blinked and looked around the group.

“Um, alright. Although it’s not simple answer. When it comes to soulmates, few things are.”

Minami didn’t say anything, she just moved over and patted the space between her and Yuzuriha.

Much to Senku’s surprise, Gen took the seat. He’d been half convinced Gen would refuse outright. It was strange, having him sit so close after so long. Although considering the topic, Senku could barely force himself to breathe normally.

“First off, you have to remember that when talking about soulmates you’re dealing with the theoretical so there’s never a clear cut answer. But, to put it plainly, you gain your colours upon your soulmate’s death because without a soulmate, the soulmate bond is rendered redundant. Without a soulmate, there’s no reason for you not to see colour.”

“Wait, so soulmate bonds are what stop us seeing colours?” Chrome asked.

“No, it’s more complicated than that.” Gen furrowed his brow in thought. “See, that actually used to be the accepted theory. It used to be believed that you were born with colour and once you were assigned a soulmate, that colour would be revoked. So, when the bond is severed or fulfilled, you regain your colour sight. But it was later proven to be the opposite. Infants can’t distinguish between any colours at all and gain their soulmate colour later in life. Usually by about six months of age.”

“Then why do we gain colour-sight later on?” It was Nikki that interrupted this time. “Does the bond give us colours?”

Gen shrugged. “I don’t know, no one can really answer that. I personally don’t believe so. Soulmate colours are just a tool to help us find our soulmate, they don’t affect our biology; all humans are born with the ability to see colours after all. Hence, gaining colour-sight upon losing your soulmate: in death this purpose is nullified and so you stop being affected by the bond. What’s the point of a sign without a purpose? At least that’s my opinion. You’re free to disagree, I have no real evidence.”

“Wait, go back to the part about babies,” Yuzuriha said. Senku didn’t miss the glance she shot in his direction before continuing. “If we’re all born without colours, does that mean that if a person doesn’t have a soulmate that they remain entirely colour-blind?”

Yuzuriha had always been irritated by Senku’s belief that he didn’t have a soulmate, so he wasn’t surprised she asked.

What did surprise him was Gen’s reaction to the question. He laughed. “That’s impossible.”

Senku sat up straight. “Wait, it is?”

Apparently, Gen wasn’t expecting Senku to speak at all and it took him a second to answer. “Well… yeah, as far as anyone can prove. A soulmate is just the person you’re most compatible with, romantically or platonically, so there’s no reason for someone not to have one. Besides, this hypothetical person without a soulmate would be born seeing colours, not without them. As I said, a sign without a purpose.”

While it wasn’t really a problem for Senku anymore, knowing that felt… better, somehow. He even cracked a smile when Yuzuriha elbowed him and mouthed ‘I told you so’.

But then Senku actually considered what it was that Gen had been explaining. A soulmate bond that led you to someone who wasn’t your other half was as useful as a bond to a dead person, it was redundant. For a second, Senku thought that could mean he was wrong. For a blissful second, he thought that maybe he’d been worrying all this time for nothing.

That wouldn’t explain away everything though. Senku knew that life threw anomalies at you whenever it felt like it, and knowing his luck he could really be the one exception. And it didn’t change the fact that Gen had been seeing colour long before they ever met.

“Gen, this is really cool and all,” Chrome said, interrupting Senku’s train of thought, “but I thought you were a magician in the old world. Why do you know so much about soulmates?”

Gen chuckled. “Occupational hazard. Soulmate media was really popular. I don’t really remember when, but they tied it into my branding at one point.”

“I remember there being a ton of soulmate stuff in your book,” Yuzuriha added. “I know my friends were really into those bits.”

“I think I’ve already said this, but most of that was nonsense. I just wrote whatever sold well.”

“Yeah, but it was brilliant marketing,” Minami said. “Soulmate advice from someone with a soulmate, it’s like talking to Yuzuriha but marketable. Although…” She paused and furrowed her brow. “I don’t think I ever learned anything about your soulmate. They must really like their privacy, huh?”

Senku felt like he may have finally reached his breaking point. The very last thing he wanted was to sit through Gen gushing about his real soulmate. He very nearly excused himself before Gen replied.

“Y’know, seeing as I don’t need to worry about PR anymore, I might as well tell you. I completely faked having a soulmate.”

He… what?

“Wait, really?” Nikki said. “How’d you pull that off? I thought it obvious when people were faking?”

“It wasn’t easy, but I had a leg up.” Gen smiled awkwardly and looked away. “My colour is a strange one, and I’m a very good actor, so everyone bought it.”

“A rare colour?” Minami’s eyes lit up like she'd smelled a story. “What is it?”

“Minami-chan, what an invasive question! You can’t just ask someone that.”

“Oh, sure you can. Especially among friends.” She leant in and batted her eyelashes at him. “And we are friends, aren’t we, Gen?”

He laughed. “I’m the manipulator around here, step off.” Minami rolled her eyes and sat back up again; but when she continued to look at him expectantly, along with the rest of the group, Gen seemed to realise he wasn’t going to get away without telling.

Senku was doing his best to act disinterested, he had kept his eyes trained directly on his hands, which were clenched so hard his knuckles had blanched white. But now there wasn’t a force in existence that could have torn his eyes away from Gen. And so, he was taken aback when, just before answering, Gen briefly glanced at him.

“It’s red.”

“Wow, that is weird!” Minami said, although she looked delighted. “I’ve never heard of someone having red eyes before. Then again, I can’t see red.”

“What sort of demon must you have for a soulmate?” Nikki laughed. “Though I guess it does somewhat suit you.”

“Doesn’t it just?”

Senku could feel Chrome and Yuzuriha staring at him. Coupled with Gen’s eyes being grey, the cat was fully out of the bag now. But it was hard to care when Senku’s entire world had just been flipped on its head.

While he may have been stubborn, Senku wasn’t quite so obstinate as to ignore facts. If Gen’s colour was red then… Senku was wrong. He’d been subjecting them both to emotional torment for months. And all for absolutely nothing. All because he was too wrapped up in his own head to think about things logically. All because he didn’t just talk to Gen about all of it a year ago when they first met.

Thankfully, that was also the point at which the group Gen had abandoned came asking after him. They joined the six of them and conversation moved on for the rest of the evening. Although Yuzuriha kept throwing subtle looks Senku’s way. Chrome’s looks were far less subtle.

By the time he managed to slip away into the privacy of his own room, Senku knew that he needed to talk to Gen.

Urgently.

Chapter Text

Senku waited until everyone had gone to sleep and most of the lights were out before he braved visiting Gen. It would be potentially disastrous if someone interrupted, either on the way or while there. It was hard enough to keep one foot moving after another without someone diverting his attention.

When he reached Gen’s room, the doorway was dimly lit from the inside. Night owl that he was, it was easy to guess that Gen would be awake long after everyone else had retired. 

Senku pulled back the leather curtain covering the doorway and peered in. He’d expected to find Gen mucking about with flowers or the multitude of tricks he hid up his sleeves. At the very least he expected to find him playing with his deck of cards, Senku had frequently walked in on him playing solitaire in the past. 

Right now though, Gen was sitting on his bed idly pushing an empty bottle around the floor with his toes. 

He didn’t notice Senku’s presence at all, too lost in his own thoughts. So Senku cleared his throat.

Gen looked up and, predictably, his expression pulled down into a frown. 

“Well, if it isn’t Senku-chan. I’m surprised you remember where I live.”

Senku winced but didn’t comment.

“Can I… Can I come in?”

It was strange, asking for permission to enter Gen’s room. He was so used to waltzing in whenever he felt like it. Gen used to do the same. It only now hit him just how much he’d missed that. 

“You’re half in already.” Gen rolled his eyes and got to his feet. “But whatever.”

Senku ducked under the curtain and felt it fall back into place behind him with a heavy thump. Even though he’d technically been invited in, he continued to stand in the doorframe, watching as Gen picked the bottle up from the floor and moved to place it alongside a few others on a shelf. 

“Did you actually want something or did you just drop by to stare at me?”

“I, er…” This was way harder than Senku had anticipated, and he knew it wouldn’t be easy. “I just thought, well…” He sighed. “We need to talk.”

Gen snorted. “Yeah, no shit.” He turned to face Senku and crossed his arms. “So?”

He supposed it was best to be direct, especially when Gen seemed to be in no mood to put up with much of this. 

“I’m sorry,” Senku blurted out, clenching his hands by his sides. “I’ve made things… difficult for the both of us and so I… I need to apologise for that.”

“Yeah, you do,” Gen agreed, his expression stonier than before. “I don’t even know what’s going on.”

“Yeah.” Senku nodded and averted his eyes. “I can explain.”

“You had better make it good.”

He wasn’t sure if he could. He knew he thought it was all pretty pathetic. 

It was difficult to find somewhere to start but, while he knew it might sound like an excuse, he started at the beginning. 

“You already know that I couldn’t see colour at all, for most of my life.”

“That wasn’t something I could control,” Gen interrupted. “I never- ”

“I know, I know.” Senku shook his head. “I don’t blame you for that, but it’s important. I just need you to understand that I spent my whole life thinking I might not have a soulmate in the first place.”

“But-”

“That’s not how it works, yeah, I know. But I didn’t until tonight. I probably should have looked into it, but I just… couldn’t. I know next to nothing about soulmates and that was a choice. A stupid one, in retrospect, but it’s too late now.”

Senku opened his mouth to continue but then closed it again. He gulped. He’d never spoken about all of this before, not to Yuzuriha, not to Taiju and not even to Byakuya. He’d barely even admitted it to himself. 

“I always told myself that I didn’t care; that soulmates are illogical and unscientific and that most people never meet their soulmate anyway. But, yknow, not meeting your soulmate and never having one in the first place are very different and… well, I just couldn’t handle it.”

He took a shaky breath. “And I guess that’s why, when I found out that you had colour-sight before you met me… I didn’t question the idea of a one-sided bond.”

Senku chanced a look up at Gen then. He was still frowning, but it looked less severe. That was something, at least. 

“I know I should have said something but just being around you… hurt. A lot. I don’t… I’ve never actually…” Senku ran his hands through his hair. “I’ve never cared about anyone nearly as much as I care about you, and the idea that I wasn’t supposed to, that you’d never feel the same… I panicked, I suppose.”

Senku trailed off and couldn’t think of anything else to say. If he thought getting it all off of his chest would make him feel any better, Senku was sorely mistaken. Now that it was all out in the open he was even more tense. Waiting for a response was agonising.

Neither of them spoke for a while, Gen just watching as Senku fidgeted under his gaze. 

Eventually though, he let his hands fall back to his sides and looked away. “I believe you.”

Senku snapped to look at Gen, but he didn’t say anything. 

“I definitely believe that you’d panic so much at emotional confusion as to completely regress. Not that I don’t understand that…” He sighed. “Need I remind you which of us has been pretending he can’t see colours for the past year.” 

Senku felt his ears start to burn. He had completely forgotten about that, it had been so long that he’d stopped noticing. 

“I guess we’re just lucky I had enough self-awareness to realise that I was jumping to conclusions. That really messed me up for a while.”

“Gen I-”

“You’re sorry, I know.” He rolled his eyes. “I know that wasn’t on purpose. But you can’t get upset at me for essentially the same thing.”

“I’m not upset with you,” Senku said, stepping forward to grasp Gen’s shoulders, forcing him to look back at him. Much to his relief, Gen didn’t shake him off. “I screwed up, and I would do anything to make it up to you.”

Gen raised an eyebrow. “Anything?”

Senku nodded. “If I’m capable.”

“You know, I’ve started to think there’s nothing you can’t do.” He smirked and leant in so close that Senku could feel his breath on his face. “Though you could always start with getting on your knees and begging for forgiveness.”

Senku blinked. He wasn’t sure if Gen was being serious. It seemed pretty demeaning, and the thought of doing it put Senku’s teeth on edge. But it was also very Gen, and if that was what it would take he’d do it. If it made Gen happy, Senku would rip his pride in half and set it on fire. 

So, Senku knelt down. 

“Wait, huh?” Gen watched in bewilderment as Senku gently rested his forehead against Gen’s waist.

Senku took a deep breath, one hand clutching onto the hem of Gen’s haori. “I’m sorry,” he said, so quietly that he wasn’t sure that Gen could hear. If he raised his voice much more though, he was worried it would break, and he wasn’t sure how much more shame he could deal with at that point. “You deserve so much more than I’ve given you.” 

He jumped when he felt Gen’s hand on his head. “You’re not wrong.” Then he crouched down too, so they were face to face. “But also, I was kidding.”

“Yeah, I suspected.” Better to have done it than take the chance though. And then, when Gen finally smiled at him for the first time in months, it was all worth it. 

“I never expected you to do something like this.” He chuckled. “You really are desperate, aren’t you?”

“Well, yeah,” Senku said, as if it were the most obvious thing in the world. “I love you, of course I’m desperate.”

Gen sputtered and his face blossomed bright red. He pouted. “You’re making it really difficult to stay angry.” He pushed back Senku’s hair and smiled. “I’m really mad at you, I swear.”

“I know, I would be too,” Senku said, leaning forward into Gen’s touch. Where their skin met burned pleasantly and Senku couldn’t remember how long it had been since they were this close. Even before, they’d never been quite so… intimate. “But maybe you won’t stay mad?”

“Maybe.” Gen’s smile softened as he ran his fingers through the length of Senku’s hair. “Although I have many conditions before I’ll even consider it.” 

“Which are?”

“Well for one you’ll have to up my cola supply. I demand at least twice as much.”

Senku laughed. “That’s doable.”

Gen moved so he was sitting on his knees, so close that their legs were touching. “And I want more blankets. And warmer clothes. And a more comfortable bed. It’s getting cold and I demand comfort. Also the second you can, you're building me a bathhouse.”

“I can do that. You’re hardly the only person that wants an onsen.” 

Gen hummed and nodded. Then he moved forward to lay his arms across Senku’s shoulders. Senku felt his face break out in a blush but he didn’t move. “And I demand overt preferential treatment. What’s the point in dating the chief if I don’t benefit from it?”

“Having my unconditional love and affection?”

“Hmm.” Gen looked up to the ceiling as if in contemplation. “Nah, I want to be spoiled.” 

Senku shook his head but grinned. He already knew there was nothing in this world he would ever refuse Gen. “Then I’ll spoil you rotten.”

“Good.” Gen leant forward so their foreheads were resting against one another. “Although I definitely also want that love and affection thing.” 

They sat like that in silence for a while, eyes shut, simply basking in each other's presence. This was what Senku had thought having a soulmate was supposed to be like, this was what he’d always anticipated. He had also thought that it was pointless and something he was comfortable living without, but he was so wrong it was hilarious. Now that he had it, this was something that Senku would kill to never give up. 

He opened his eyes and watched Gen’s face, letting himself really appreciate how beautiful he was. The soft lines of his cheeks, the delicate curve of his nose, the way his eyelashes fluttered as he blinked.

Without thinking, Senku lifted his hand to Gen’s face and ran his thumb against his cheek. Gen opened his eyes in response and Senku stared back. 

He had wondered what he would do when he finally met the eyes that had left him in a world without colour. He had thought he might hate them, hate whoever they belonged to. But right now, staring directly into them, staring at the brilliant, beautiful person they belonged to, he could feel nothing but pure adoration. 

“So,” Gen said, a small smirk rising to his face. “How long are we going to sit like this until you finally kiss me?”

Senku needed no further invitation. He pushed forward until his lips met Gen’s.

It was strange. Senku had never kissed anyone before and it was obvious that Gen hadn’t either. Neither of them knew what they were doing, but every second that passed, every movement they made, felt simultaneously electrifying and downright serene. As Gen curled his arms around Senku’s neck, pulling him forward so their chests were flush, Senku thought that nothing in his life had ever, and would ever, feel quite so right as this did. 

But, as all good things must, the moment had to eventually end. As inexperienced as they both were, they inevitably had to surface for air.

They returned to a comfortable silence and Senku gently stroked Gen’s cheek as he caught his breath, delighting in the sensation of Gen playing with the hair at the base of his neck. 

But then, try as he might, Senku couldn’t suppress the yawn that passed his lips. 

“Tired?” Gen said, a statement more than a question. 

“Apparently.”

Senku wasn’t surprised, it was late and he’d been working himself to the bone for the past week. Now that he was allowing himself to relax, to indulge in something truly good, his body decided it was time to shut down all at once. 

“Stay.” Gen was so quiet it was barely a whisper, but Senku heard. “Here, tonight.”

It was music to Senku’s ears. He nodded.

Silently, they got to their feet and collapsed onto Gen’s bed. Gen reached up to turn out the light and plunged them into darkness as they wrapped their arms around each other, tangling their legs together like it was how they were always meant to be. 

Lying there was almost surreal, Gen’s head tucked beneath his chin as they lay so close that Senku could feel Gen’s breath tumbling down his chest, that he could feel his heart beating under his embrace. 

If it didn’t feel so real and wonderful, Senku might have thought he was dreaming. 

At the very least, he knew that if it meant he could stay like this forever, Senku never wanted the sun to rise.