Archive of Our Own

It was a calm evening. The Perseus had anchored near some coast to gather materials, food, and anything else the team might need before setting sail again. Now, after a quite exhausting day, they sat around a fire, just talking and drinking while the fire already burned low. The ship lay quietly nearby.

Sai sat slightly apart from the center of the circle, he wasn’t exactly distant, just... also not into the loudest parts of it either. There was a cup with some alcoholic liquor in his hands. He had not been drinking much, just enough so that he wasn’t the only completely sober one.

It was... a nice evening. Peaceful.

That word felt strange, considering everything that had happened until he too got depetrified. Stone wars, revivals, conflict, rebuilding civilization from nothing... and yet here they were, sitting around a fire like it was the most natural thing in the world.

And now they even want to build a computer in this goddamn prehistoric world. Something so precise and complex, something that required nonstop planning! It almost felt overwhelming, rebuilding that level of technology completely from scratch. But Senku would figure it out. Senku could figure out everything. That certainty had settled in him.

And after that, their next plan was... building a rocket. Space didn’t feel so far anymore. Senku could get even there. Sai’s eyes moved over the group and landed on him. Senku was sitting near the fire, half-listening to the conversation around him while he was obviously thinking about something else entirely.

Yeah... he would do it. He and...

His gaze shifted to Ryusui.

Who was sitting on the other side, impossible to ignore. He was louder than the others and stretched out comfortably with one arm behind him and a full cup in the other hand. The light of the fire let his hair shimmer and his eyes got brighter when he laughed. He looked completely at ease, just like he belonged wherever he was.

And Sai... still wasn’t entirely used to it.

To his younger brother.

The word sounded strange in his mind, not unwelcome, just... unfamiliar to use, after all this time. They were still rebuilding their relationship, doing it one step at a time. But they were improving through conversations, arguments, and simply trying to understand each other better.

It felt real now. And maybe that was why it got complicated.

Because the closer they got, the harder it became for Sai to ignore the way he saw him now. A way he really wasn’t supposed to. He knew that was something he should have shut down a long time ago. Sai remembered having these thoughts even before petrification, back when ignoring them had still been easy because of the distance. He always told himself it didn’t mean anything. That it would pass.

“You’re absolutely lying!” Chrome said, leaning forward with bright eyes.

I am.

Across the fire, some laughter broke out again. Gen was saying something exaggerated, his hands were moving as he spoke, clearly in the middle of a story.

“Ohhhh am I?” Gen placed a hand over his chest, mock-offended. “I would never, my dear Chrome.”

“You literally just did!”

Suika looked between everyone around the fire with obvious excitement, as if simply being there already made her happy.

Francois moved through them quietly, they refilled cups and adjusted things without being asked. When they passed Sai, they paused to offer him another drink. He hesitated at first, but then nodded.

“Thank you.”

For a brief second, Francois seemed to reconsider something. Then they leaned down slightly.

“You know. I have seen him hurt before.” Francois said quietly into his ears. “I would prefer not to see it again.”

Sai let out a small breath. “You’re assuming too much. Don’t worry.” He said, more to himself. Francois paused just a moment, like they were considering saying more, then simply inclined their head and stepped away.

I’ll keep it under control.

The problem was, he wasn’t entirely sure he believed that.

Kohaku suddenly shifted where she sat, looking between everyone like she was waiting for the right moment. It didn’t take long.

“Okay, everyone! We should play a game!”

A collective annoyed reaction followed immediately.

“Not againnn...” Chrome groaned, as he was dropping back onto his hands.

Gen laughed. “I knew she would say this at some point.”

Kohaku sat up straighter, clearly unbothered by missing enthusiasm. “Let’s play spin the bottle!”

That led to an even louder response.

“Nooooo.” Chrome said immediately.

“We literally played that last time.” Gen added, still smiling but with a hint of resignation.

“And the time before that.” Came another voice.

Kohaku frowned slightly, like she didn’t see the issue. “And? It is a good game!”

“It’s your favorite game, since Chelsea told you how to play it.” Chrome corrected.

Senku looked up. “Listen, I’m not doing a repeat of last time.”

Kohaku frowned. “What was wrong last time?”

“I don’t want to kiss other people on the lips.” He said. “Not even a peck. Let’s change this rule.”

“But Senku, that is how the game works!”

“Then the game needs an update.” He replied. “A kiss on the cheek should be fine too, don’t you think?”

She paused, thinking it through.

“You did not seem concerned when it was Gen.”

Senku shrugged. “If it lands on Gen, it’ll be fine.”

Gen blinked, then smiled. “Oh? Now I feel special.”

“We’ve done this enough times. It’s not an issue.”

“...I’m choosing to take that as a compliment.”

Kohaku nodded. “Alright. Accepted.”

Sai tilted his head a little and looked up at the others. “Spin the bottle, huh... isn’t that kind of a college thing?”

A few of them laughed.

“It is.” Gen said easily, swirling his drink. “But somehow we are dragged into it repeatedly.”

“Because it is fun!” Kohaku replied without hesitation.

“It’s fun for you!” Chrome muttered.

Chelsea rubbed the back of his neck, already looking nervous. “Last time was kind of intense though...”

“That’s putting it lightly.” Gen added, clearly entertained by the memory.

Sai glanced between them, curiosity slipping in despite himself. “What happened?”

Chrome groaned immediately. “Don’t remind me.”

“Oh no, we are absolutely reminding you.” Gen said, sitting up a little straighter, now talking directly to Sai again. “He spun, it landed on Kohaku, and he just froze. Completely. We thought he was going to pass out.”

“That’s because she was staring at me like she was about to fight me if I do something!” Chrome shot back.

Gen let out a quiet laugh. “And then, it was the quickest kiss I’ve ever seen. It barely even counted.”

Chrome buried his face in his hands. “I hate you all.”

Sai huffed through his nose, not quite a laugh but close. He caught himself looking over to his brother. Ryusui looked completely amused, like the whole thing was just another story to enjoy, another moment to collect.

...Right.

Sai leaned back slightly.

“Doesn’t sound that bad.” He said in an even tone.

“Just wait until it’s your turn. No pulling out, no matter who!” Gen replied lightly.

Sai didn’t answer that. It won’t be anything. It’s just a silly game.

There were... what, seven of them who were playing? Eight, including him. Kaseki had already disappeared to bed not long ago, grumbling something about old men needing proper sleep and Francois had made it very clear they intended to remain an observer only.

Okay, so eight active players, huh? The bottle would have to land on him first. That alone was already only a one-in-eight chance. Then it would have to land on Ryusui second out of the remaining seven people. One specific outcome out of fifty-six possible combinations.

Sai stared down into his drink for a second.

Calm down. That’s not even two percent.

Even if he counted the reverse situation too, which was Ryusui first and then him, the odds were still barely under four percent. This was statistically insignificant. So there was no reason to freak out about it. Realistically, it probably would not happen at all tonight.

...Unless the game continued long enough. Repeated probability was significantly less comforting.

But… no.

It’s not going to happen. And even if, it’ll just be a peck. No big deal.

The bottle stayed between them for a moment, like no one wanted to be the first to actually start.

Then Kohaku leaned forward and spun it with visible enthusiasm. It rattled in a wide circle before slowing, then finally pointing straight at Chrome, and then at Suika.

Chrome looked like someone had just been sentenced publicly. He glanced at Senku, who gave absolutely nothing away, then at Kohaku, who was watching like this was some kind of ritual.

Gen rested his chin on his hand. “Redemption time, Chrome. Try not to freeze.”

“I’m not!” Chrome snapped, which did not sound convincing at all. Technically Suika wasn’t even much younger than him anymore. Unfortunately, Chrome’s brain had never updated that information.

Suika blinked at him from across the fire, looking more curious than nervous.

Instead of arguing, Chrome leaned forward abruptly and pressed a quick kiss to her cheek, clearly copying Senku’s earlier clause. It was so fast and awkward that Suika looked surprised for a second before breaking into giggles.

“There!” Chrome muttered immediately, retreating back to his spot. “Done.”

“Awwww, that was tragically wholesome.” Gen sighed.

Kohaku crossed her arms. “You are all avoiding the spirit of the game, Chrome!”

Chrome didn’t care. To him, Suika still felt more like family than anything else.

Sai watched quietly and sipped at his drink again, a little amused. It seemed simple. A bit of embarrassment, some laughter, nothing that lingered.

The bottle spun again. It slowed and settled on Gen and then on Ryusui.

Gen’s smile sharpened immediately. “Ahhh. Now this is interesting. Captain, do try to leave a lasting impression! I bruise easily.”

Ryusui leaned forward without hesitation, a confident grin on his lips. “Ha-HA! If you bruise from this, I’d be concerned.”

“Ohhhhh... promises already?”

Chrome groaned. “Can you two not narrate it like that?”

They leaned in. There was no awkward shuffle, no hesitation at all. Their lips met cleanly, and they stayed.

Sai felt it in his stomach before he understood it.

One second.

Two.

Three.

They were still kissing.

Four.

Five.

Why are they still...!

His neck suddenly felt far too warm and his grip tightened around his cup without him meaning to, his fingers pressed harder into the ground.

There’s no need to take that long. It’s a game. ... Just pull back already.

Ryusui wasn’t laughing it off or rushing it. He looked... comfortable.

Like this was nothing.

That thought came fast and it felt sharp and ugly.

Tze. Anyone will do with him, apparently.

The bitterness surprised him. It felt mean. He did not like that it came from him.

Why do I even care?!

The question came too late. His heart was already beating harder than it should have because of something so random. He shifted slightly, suddenly aware that his face felt warmer than before.

They finally pulled apart.

Gen looked pleased. “Not bad at all. I can see the appeal.”

Ryusui smirked. “High praise.”

Sai forced himself to look away.

As if. It didn’t even look real. More like bad acting.

That was a lie and he knew it.

Suddenly the bottle spun again.

This time it stopped on Gen and then on Senku.

Chrome immediately perked up. “Oh, come on. Really? You can just kiss your boyfriend?”

“Jealous?” Gen smiled.

Senku rolled his eyes but leaned forward first, his fingers hooked into Gen’s sleeve as he pulled him closer. The kiss that followed was quiet and familiar. The others went silent for a second.

Sai found himself watching a second longer than he meant to.

And as the bottle spun again, slower now, it tipped on...

...himself.

Oh.

A few voices cheered, someone laughed, another one probably made a comment, but it all blurred together for a second. The bottle was already spun again.

This time he didn’t dare to look away, his eyes followed the movement closely, taking its time circling around before losing speed.

It stopped at Ryusui.

No. Oh no.

Shit. Shit Shit Shit.

Sai’s heartbeat kicked so suddenly he actually heard it in his ears. His palms went damp instantly. He wiped one subtly against his pants before pushing himself forward.

This is ridiculous. Stop acting like an idiot! It’s the same as the others. It means nothing.

Across from him, Ryusui was not smiling. He was watching him as he waited.

Sai swallowed.

Gen’s voice sounded amused. “Don’t disappoint us. The captain has already set expectations.”

That stung. Thanks, I know, I saw that!!

Sai moved forward before he could hesitate. If he reacted awkward now, people would notice. And if he gave himself even a second to think more about it, he knew his thoughts would get stuck in his own head. His hand came up and rested on Ryusui’s shoulder, the sudden warmth under his palm sent another stroke through his chest.

Just a quick peck. You can do it.

Their lips touched. And for a second, it stayed controlled. But then Ryusui’s hand slid to his side and pulled him closer. Deliberately.

Sai’s breath caught.

The shift was immediate and undeniable. His grip tightened, his fingers curled slightly into the fabric at Ryusui’s shoulder.

He could feel the heat between them now, the solid press of Ryusui’s body as the distance disappeared completely.

Why is he not stopping?

...Why am I not stopping?!

The thoughts collided. His heart was beating ridiculously fast. His other hand hovered awkwardly in the air for a moment before he settled it lightly against Ryusui’s chest, maybe just to steady himself.

This wasn’t like the kiss with Gen.

No.

It was worse. Because this felt intentional and Ryusui was not performing some bullshit. He was leaning into it as if he had been waiting for it to happen.

Sai’s mind raced.

He didn’t hold Gen like this. ...Yes he did. It doesn’t matter, stop comparing!

The jealousy was there again. It wasn’t supposed to feel like this and he wasn’t supposed to want more...

But truth was, he didn’t want it to stop. And that thought scared him more than the kiss itself.

He finally pulled back abruptly, breath uneven. His hand dropped from Ryusui’s shoulder.

For a moment no one spoke.

Then Gen let out a slow, theatrical whistle. “Oh dear, that was definitely not the cheek. Should we be concerned, or just impressed?”

Chrome blinked. “You guys... uh. That looked... wow.”

Kohaku nodded seriously. “It lasted way longer than the others! Nice!”

Ryusui leaned back slowly, his gaze still locked on Sai, no embarrassment in it at all. “Ha! No one said there was a limit!”

Sai couldn’t look at him. His palms were still damp. His heart had not slowed down. And the worst part was that he knew exactly why.

The game kept going, but it didn’t feel as before anymore.

People laughed, someone complained about the next pairing and Gen made a few comments. But Sai barely followed any of it. The noise blurred together into something distant, like he was sitting just outside of it.

What... was that?!

He still answered when someone spoke to him. He even smiled once or twice. But his focus kept slipping, always back to that moment. Back to the pressure of Ryusui’s hand at his side and to the fact that he hadn’t pulled away immediately.

Fuck... why didn’t I...

He cut the thought off.

At some point the game was over and the group began breaking apart naturally. A few people got tired, others complained about the cold and so one by one they started going back toward the ship, to their cabins.

Sai stood up as well. His plan was to walk back calmly, wash his face and reset. By morning he certainly would be able to manage the situation again.

But he barely made two steps before fingers wrapped firmly around his wrist. He turned, already concerned at how quickly his heart reacted again.

It was Ryusui.

“I’m not letting you just walk away from that, Sai.” He said, not loudly but with enough force so that Sai immediately stiffened.

“From what?” Sai replied, a little too fast.

Ryusui’s grip tightened, just slightly, to make the point clear. “Hah. Come on! Don’t act like you don’t know what I mean.”

Sai looked back toward the others. They were already quite far now. He pulled his wrist free and tried to ignore the upcoming heat. “We were playing a game, Ryu. You’re making this unnecessarily dramatic.”

Ryusui stepped forward, closing the distance Sai had just created. His eyes dropped briefly to his mouth before coming back up. “I desire to do it again.”

Sai stared at him. “What?” Had he heard that right?

“The kiss.” Ryusui said plainly. “I want to do it again. Now. Without being in a game.”

He did. And the directness hit him hard. Sai felt the reaction in his body before he could find an answer. His chest tightened and his palms warmed again.

“I think you’ve had too many drinks.” Sai said while he forced his tone back into control. He couldn’t let that happen.

Ryusui shook his head slowly, his eyes never leaving Sai’s. “I know exactly how much I’ve had. And I know exactly what I want. Don’t do that.”

“Do what?”

“Act like kissing me didn’t mean anything to you, too.”

Sai felt his pulse getting faster again “It didn’t. It was a game.”

“Bullshit.”

The word landed sharp. Sai’s brows pulled together. “You kissed Gen the same way! So go and approach him instead!” That came out faster than intended and the second it left his mouth, he knew it. But it would make everything so much easier. Fuck.

Ryusui’s eyes narrowed slightly.

“...wait. Are you jealous? Is that what this is about?”

“It’s not about anything,” Sai shot back immediately. “I’m just stating a fact.”

Ryusui took another step forward.

“The kiss with Gen was totally different.” Ryusui said quietly.

Sai’s heartbeat kicked harder.

“It wasn’t.” He insisted. “You leaned in. You held it for a bunch of seconds. Same as with me.”

“No.” Ryusui said, and there was no humor left in his tone now. He sounded serious. “It really didn’t matter with him. Not for me.”

Sai looked away for a moment.

“It was the same...”

Ryusui didn’t back off. “Stop lying.”

Sai quickly looked back at him. “Excuse me?”

“Sai... come on...” Ryusui said, voice low, steady. “You’re trying to convince yourself because you don’t want to deal with... this. But if it had been the same, we wouldn’t be standing here arguing about it...”

The space between them felt even smaller again. Sai’s hands curled at his sides. He was painfully aware of how fast his pulse was beating now and how warm his face felt.

“This is getting absurd.” He said. “You’re drunk, you’re reading into things and I’m not playing along.”

Ryusui shook his head. “I wanted that.” He reached up then, his fingers brushed lightly against Sai’s side. Sai felt it like a spark. He could feel Ryusui’s breath every time he spoke now.

“That’s not...” He started, then stopped.

Ryusui didn’t give him time to recover. “I’ve wanted that for a while, you know...”

“This is a bad idea, Ryu.” Even to himself, he sounded less certain each time he said it.

“It was just a silly moment. And that doesn’t change anything.”

“It changes everything.”

“It doesn’t!” Sai insisted, sharper now. “We’re...”

He stopped. The word stuck, but Ryusui didn’t say it for him. The silence stretched just long enough to make it even worse until Sai finally forced it out.

“We’re brothers, remember?”

Ryusui didn’t flinch. That should have ended it. The ultimate argument. It didn’t.

“And?”

“And that matters!”

“Why?”

The question caught him off guard. Why? Huh... Sai opened his mouth but then closed it again. His mind searched for all the reasons. Social structure, logic... but all he could find was Ryusui standing close and the memory of that kiss, like it was still happening.

“Because it complicates everything.” He finally said.

Ryusui studied him for a long moment. “Tell me you didn’t feel anything. When we kissed.”

Sai’s heart was pounding hard and his hands were sweaty again. He thought about the moment when their lips met. About how he had not pulled away immediately.

“I...” he started, then stopped.

That was the problem. He couldn’t. And they both knew it.

“Kiss me again.” Ryusui murmured.

Ryusui moved closer, slowly this time but oh so deliberate, giving him every opportunity to step back. Giving him time to stop it. Sai didn’t move. And that was the answer.

“This is a bad idea...” Sai said again, but it sounded weaker now. Ryusui’s eyes did not soften.

“Then stop me.”

He held his gaze the entire time. Sai hated how simple that sounded. Because he could, he absolutely could. But...

He didn’t. And their lips met again.

This time it wasn’t awkward or careful for long. It started slow, almost like they were both checking if this was really happening. Sai’s heart was already beating way too fast the whole time and after a moment it didn’t really feel like a mistake anymore. Ryusui pressed closer and Sai’s breath caught quietly as the distance between them disappeared. His hand tightened in Ryusui’s shirt again without thinking, his fingers curling into it like he needed something to hold onto.

Oh gods. This is...

He didn’t finish the thought. Instead, he pulled him even closer.

The kiss deepened. Sai barely noticed the moment as his lips parted against Ryusui’s, only the sudden warmth of Ryusui’s tongue in his mouth and the way it made his thoughts completely scatter. Sai leaned in just a little more, matched the pressure instead of fighting it. It felt so much hotter now, more real. Sai’s thoughts were still trying to catch up.

This is really happening. We’re really...

That thought came out of nowhere and it made everything worse. Or better. He couldn’t tell anymore.

Sai pushed forward, his tongue gliding against Ryusui’s now, matching every movement with one of his own. He could feel Ryusui right there, not holding back or treating this like something temporary. And all he could think about was that he really didn’t want to stop. But he should.

When they finally pulled apart, Sai was breathless. His hands were still gripping Ryusui’s shirt and for a second he just stayed there, unmoving.

Then he abruptly stepped back.

“We need to stop.” He said, sharper than he intended.

Ryusui didn’t move back.

“If you wanted to stop, you would’ve.” He replied, calm, like he was stating something obvious.

Sai shook his head. “It doesn’t matter. It was a mistake.” Again.

“It didn’t feel like one.”

“That’s not the point!”

Ryusui tilted his head and studied him, still far too close. “Then what is the point? Give me a clear answer!”

Sai opened his mouth once, then closed it again. The truth was, he didn’t have a clear answer at all.

“You know we’re not supposed to do this. Let’s stop.” He said finally. But is it still... true?

Ryusui watched him for a moment, then exhaled quietly. He was not arguing anymore, not pushing further. At least for now.

“Tze. Alright.” He said.

Sai blinked, caught off guard by how easily that came.

But Ryusui didn’t step away. Didn’t leave.

It was silent for a second before he added, more casually this time, “At least don’t leave me standing here alone. Come on. Just walk me back.”

Sai exhaled slowly and ran a hand through his hair. “You can’t possibly think this is helping.”

“That’s not a no.”

“...okay.” Sai muttered. “I’ll walk you back. Nothing more.”

The walk back to the Perseus was quiet. They walked side by side, close enough that Sai was constantly aware of his brother’s presence. Ryusui didn’t fill the silence right away, which somehow made it worse. It left too much space for Sai to think, and thinking was exactly what he needed less of right now.

But after a while, Ryusui spoke again.

“You’re overthinking it, Sai.”

Sai let out a quiet, humorless breath. “Of course I am. One of us has to.”

That was the difference between them. Ryusui followed his feelings first and worried about the consequences later, if he worried about them at all. Sai was supposed to be the responsible one between them. He had spent years convincing himself to draw lines Ryusui never would. But the old world was gone now and suddenly, deep down, he caught himself wondering why he was still holding onto rules that no longer seemed to belong anywhere around them.

They reached the ship not long after.

Ryusui’s cabin was larger than the others, one of the few privileges that came with being captain, even if large on the Perseus still meant practical more than luxurious. The bed occupied most of the space opposite the door only a few steps away from the entrance. It was bigger than the beds in the ordinary cabins, definitely enough for one person to sleep comfortably, maybe even two if neither of them moved around much. There was also a desk, some shelves, a lantern... everything was neat and functional.

Sai realized after a moment that the room barely looked lived in and that Ryusui probably only came here to sleep. That made sense. Most of his time was spent on deck with everyone else, steering the ship, yelling orders, dragging people into plans they definitely had not agreed to five minutes earlier.

Sai stepped slightly ahead, already preparing to end this here, to put distance back where it belonged.

“That’s your cabin.” He said, gesturing vaguely toward the bed. “You’re fine from here.”

Ryusui laughed softly and sat down on the edge of the bed. As Sai turned toward the door, fingers suddenly closed around his wrist.

He sighed quietly, but didn’t turn around.

“Ryusui...”

It came out lower than he intended.

Ryusui’s fingers tightened, like he knew exactly what Sai was about to do and was already preparing for it.

“Please stay.”

Something in Sai’s chest tightened painfully. Because... something was odd in this sentence. Huh. That was not Ryusui’s usual voice.

He stilled for a moment.

Damn. He should leave. Seriously, what the hell was he still doing here? This was a bad idea to begin with and he knew what staying here meant, even if he didn’t want to admit it directly. It meant letting this become something real. And the problem wasn’t just that it was risky or complicated, it was that part of him wanted to see where it went anyway. He wasn’t moving and that was the problem, because the longer he stayed the more it stopped being an accident and started being a choice. But the way Ryusui was holding onto him right now, the way he hadn’t let go even once... Ryusui really truly wanted... more. All of it. Shit. Of course he did. That explained too much. The way he’d reacted earlier, the way he hadn’t hesitated even once... Ryusui meant it.

Okay, fuck it.

“Ryu... if I stay...” Sai said, breath unsteady, “This isn’t going to stay harmless. You get that, right? I can’t guarantee what I’ll do.”

Sai realized his hand was tightening around Ryusui’s wrist instead of pulling away. His voice wasn’t as steady as he wanted it to be.

Ryusui’s answer was quick.

“I don’t want you to hold back!”

The honesty got him. Sai swallowed. He opened his mouth to answer and realized he’d forgotten what he wanted to say.

“You don’t understand what you’re asking for.”

“I know exactly who I’m asking. I’ll take whatever you give me.” He said quietly.

That should have pushed Sai out the door immediately. But instead, something in him snapped.

Sai turned around and stared at him. At the way Ryusui was sitting there pretending to be composed. But his shoulders were tight, his breathing was not quite even and his hand was still not letting go.

He seemed calm but he was barely holding himself together. He was nervous.

And suddenly Sai understood something awful and simple.

Ryusui must have been thinking about... all this for far longer than Sai had realized.

Slowly, Sai reached back with his free hand and pushed the door close.

This is stupid.

This is reckless.

This will ruin everything.

But... we both want this.

“...you don’t know what you’re getting yourself into.”

Ryusui’s mouth curved. “Only one way to find out.”

Sai felt his restraint finally crack.

He suddenly stepped forward, closed the distance in one motion and pushed Ryusui back onto the mattress with more force than he intended. Not violent or urgent, but like he needed the change of control to keep himself from unraveling.

Ryusui fell back with a surprised look on his face. Sai hovered over him, one hand beside his head and the other tangled in his shirt to hold him right there.

His heart was pounding so freaking hard.

“Are you actually sure?” Sai asked, but his voice was low and rough. “If I don’t stop right now” He added, quieter now “I won’t stop halfway.”

That was the closest he would get as a warning. Ryusui looked up at him, his eyes bright in the dim light. Slowly his grin came back.

“I was hoping you wouldn’t.”

And that was enough.

Sai moved before he would overthink again.

He leaned in and kissed Ryusui hard, firm and direct. Not testing this time. His mouth pressed fully and when Ryusui answered right away, his arms were sliding around Sai’s shoulders and he pulled him down. Ryusui made a quiet sound into the kiss, something like a laugh that turned into a breath.

“You really meant it...”

Sai didn’t answer. He kissed him again, deeper now, his tongue pushed clumsily. It was not smooth or practiced, just pure intention.

Ryusui reacted instantly and moved up to meet him, one hand sliding against Sai’s side as the kiss deepened. Their bodies pressed together and Sai could feel the change right away.

He pushed Ryusui back onto the mattress, a little bit too fast and too rough, but Ryusui only let out a short breath while he held onto him.

“Careful.” Ryusui muttered, but he was smiling. “Or don’t. That works too.”

Sai still hovered over him, already breathing harder than before.

“This is still a bad idea.” He said quietly.

Ryusui looked up at him, eyes sharp, focused. “Then let it be a bad idea for a little longer...”

For a second Sai just stared at him, then he pulled at Ryusui’s shirt, his fingers not as steady as he wanted them to be. The fabric resisted for a moment and he clicked his tongue before tugging harder.

The captain noticed the problem and tugged the shirt over his own head before Sai could fight with it any longer.

“You could’ve done that immediately.”

Ryusui laughed under his breath. “You’re the one rushing.”

“Don’t be so smug about it.” Sai avoided to look at him directly.

Sai’s hands found Ryusui’s bare chest and lingered there for a second too long, the warmth beneath his palms making his thoughts like jelly again.

Ryusui noticed. Of course he did.

“Thinking again?” He asked, quieter now.

Sai shook his head once but swallowed. “No. Just... give me a second.”

It sounded a bit off, like he was still trying to convince himself to continue. Then his hands moved again, slower this time, sliding down over Ryusui’s chest and his stomach. More careful than confident.

Ryusui shifted slightly under him, a small breath slipping out.

“Don’t... don’t stop there.”

Sai’s mouth tightened just a little. “You’re talking a lot.”

“You’re moving slow.” Ryusui shot back, but his voice already sounded less steady.

Sai’s hand reached the waistband. He hesitated again, just for a moment.

He could still walk away.

That thought came and went quickly. His fingers hooked into the fabric and he pulled. Ryusui lifted his hips to help, still smirking.

“Finally. Was starting to think you’d stop halfway...”

Sai glanced up at him. “Want me to?”

“No.” Ryusui’s shook his head. “Absolutely not.”

Sai let out a quiet breath and pulled the rest down, exposing him fully. That changed the atmosphere again. Sai sat back just enough to look. Just for moment, but it was enough to make his face heat up once more.

He slowly exhaled. Damn, that was a view.

Ryusui watched him closely, that same sharp focus, but his chest was rising faster now.

“You’re staring.”

Sai blinked. “Shut up.” But there was no bite behind it.

He reached for his own clothes next. This time he hesitated longer than before. His hands paused at the hem of his shirt as his mind tried to catch up.

This was going too fast. He pulled the shirt off anyway.

Ryusui’s eyes tracked the movement. “Finally.”

Sai ignored that and finished pulling his pants off in one quick motion. The fabric hit the floor. When he leaned back over Ryusui, there was nothing in the way anymore, both were completely bare.

Ryusui’s hands came up right away, settling on his back again, pulling him down. He was not teasing, he just wanted him closer.

“Stop pausing. Just... do.” Ryusui said softly.

Sai let out a heavy breath. “I’m trying not to mess this up.”

The words slipped out of his mouth before he could stop them.

Ryusui blinked, then smiled a little. “Relax. You won’t.”

Sai didn’t answer. But he leaned down again, yet this time his mouth didn’t go to Ryusui’s lips.

It moved to his neck.

The reaction was immediate. Ryusui’s head tilted back, a quiet sound escaped him. Sai stilled for a second. Then he did it again and pressed his mouth there, slower now and more deliberate.

Ryusui’s grip tightened. “Ah... Sai...”

Hearing his name like that sent a bubbly feeling through Sai’s chest.

He shifted lower, kissed along his collarbone while his hand moved at the same time. It slowly wrapped around Ryusui’s cock, not as confident as before, but not stopping either.

Ryusui jerked up.

“Ffff... okay, yeah, that works...”

Sai almost laughed, but it came out as a small breath instead. He didn’t move his hand right away, just held him, feeling the weight, the heat. Trying to process it.

Then his hand started to shift over Ryusui’s cock. Slow at first. A bit uneven.

Ryusui reacted right away, breath catching. “Gods... don’t slow down now...”

Sai’s mouth brushed against his chest. “Hey. I’m still figuring out what you would like.”

“You. Just more of... you.” Ryusui mumbled.

Sai adjusted and moved a bit faster now. His thumb stroked over the tip and Ryusui’s breath hitched hard.

“Ah... Sai...”

Sai froze for half a second before he could keep going. That reaction would definitely stay in his head.

His movements got more certain and focused after that. He watched every small reaction, every shift.

Ryusui’s hands were not steady anymore. One was gripping Sai’s shoulder, the other sliding along his side, pulling him closer without thinking.

“Sa... don’t stop, just...”

His words cut off into a soft moan when Sai pressed his mouth back to his chest.

Sai swallowed. Holy shit, this was getting to him. After a moment Ryusui’s hand slipped away, reaching toward the nightstand. He fumbled for a second before pulling something out and pressing it into Sai’s hand.

Sai slowed, frowning slightly. “What is this?”

“Just use it.” Ryusui said, breath uneven.

Sai looked down, at the small tube of lubricant, then back at him. It took him off guard. “Wait... how long has the Stone World had lube??”

Ryusui huffed, cheeks flushed. “Don’t start. It was necessary.”

Sai stared at him for a second, then let out a quiet breath, almost a laugh.

“Of course it was.”

He opened it anyway. His movements slowed as he spread it onto his fingers, the feeling making him pause again for a second. Then he looked back at Ryusui.

“You’re sure?”

Ryusui met his eyes. “Yeah.”

Sai nodded once.

“Okay.”

He shifted his position slightly. His hand left Ryusui’s cock, and Ryusui made a small sound right away.

“Hey... don’t just...”

He cut himself off when Sai’s fingers touched him somewhere else and his whole body tensed.

“S-Sai...”

Sai stopped there, watching him closely. “Still okay?”

Ryusui nodded quickly, even though his breathing had already changed. “Yeah! More than okay just... don’t stop now.”

Sai moved again, careful at first before he gently eased one finger inside. The lube made it easier. Ryusui reacted to every bit of it. His grip tightened, loosened, then tightened again.

“Ahhh... yeah... that’s...”

His words broke off into a softer sound.

Sai swallowed again. Hearing him like this was really doing something to him, just like before. He leaned down and kissed him, it was a bit messy but it worked. Ryusui kissed back immediately, clinging to him now.

Sai added another finger and Ryusui’s whole body jerked. Sai’s fingers stayed still for a moment, not moving yet. Then he pulled back just enough to look at him. “Too much?”

Ryusui shook his head fast. “No! No... keep going.”

“You’re... quite tense.” He said, a bit quieter.

Ryusui let out a shaky laugh. “Yeah no shit.”

Sai huffed softly. “I’m serious. If it hurts, just say it.”

“If it hurts, I’ll tell you.” Ryusui replied. Then he added, a little breathless “But don’t hold back on me now.”

Sai hesitated, but then moved slowly again.

Ryusui’s grip tightened immediately. “Gahhh... yeah, that’s... oh keep doing that... Ff... Sai...!”

Sai breathed a bit heavier now, and did keep going.

“You’re not holding back at all, Ryu.” He muttered.

Ryusui let out a breath that almost sounded like a laugh. “Why would I?”

Sai hesitated for a second, then moved again, a little less careful this time. The reactions got louder, less controlled. Ryusui’s head pressed back into the mattress, his hands gripping wherever they could.

“Sa... Sai... shit...”

Sai felt that in his chest. He shifted again, adjusting slightly, then after a moment, added a third finger. Ryusui’s reaction was immediate. His back arched, a louder sound breaking out.

“Oh gods... Sai... please...”

Sai froze. That simple word truly did something to him.

“Say that again.” He muttered, almost without thinking.

Ryusui’s hands pulled Sai closer.

“Please.”

Sai exhaled sharply. His thoughts were all over the place, Ryusui’s reactions already did things to him. He pulled his fingers back slowly, watching him while his breath was still uneven.

Ryusui looked up at him, flushed, his eyes unfocused and his chest rising fast.

“I want you.” he said, voice strained.

Sai moved forward again, positioning himself closer. He was already hard. That part was impossible to ignore now. He looked down at Ryusui for a second.

“We’re really doing this...” Sai said quietly.

“Yeah. We are.”

Sai shifted even closer. For a second, he just stayed there, hovering, his own cock already twisting and aching. The atmosphere between them felt different now. It was not just tension or curiosity. It was way more and way heavier. Ryusui watched him, his fingers tightened where they held onto him.

“Sai...” He said again, softer this time, almost a pull.

 “I know.” He muttered.

Sai reached down, adjusting himself. His hand that was not as steady as he wished for it to be. His other hand was put beside Ryusui’s head, it kept himself from collapsing forward completely.

There was a brief pause. Sai hesitated. Not long, just enough for his breath to catch. Then he pushed forward. Ryusui’s reaction was immediate. His whole body tensed, a sharp sound breaking out of him.

“Ah... nngh Sai...!”

Sai froze for a second. He stayed like that, letting both of them adjust.

“Too much?”

Ryusui shook his head quickly, even though his fingers dug harder into Sai’s arms.

“No...”

Sai tried to steady himself. “Okay... just give me a second.”

He didn’t move for a moment, his forehead dipped slightly as his breath came out heavier than before. It felt different but so much better than he had expected.

“...shit, Ryu...” He muttered again under his breath.

Ryusui let out a weak laugh.

Sai huffed quietly but then he started moving. Slow and careful at first, even if he was trying not to be. His rhythm was uneven, like he was still figuring this out and still adjusted it with every new motion.

“Ah... okay... yesss... keep going...”

His pace picked up slightly. Ryusui reacted right away. His hands slid up Sai’s back.

“F-fuck Sai... ah shit... move fast- argh”

Sai leaned down without thinking, his movements getting a bit more certain.

“...faster?”

“Y-yeah... don’t... ah... don’t go slow...”

Sai didn’t argue. His pace picked up.

“Ah... shit yes! Fuck... just like th- ngh!”

Sai moved again, deeper this time. Ryusui’s breath broke into a louder sound.

“Sai... nngh... fuck...”

Sai’s thoughts slipped even further away. This felt so good and it was too easy to get lost in.

“You’re... reacting a lot.” He muttered.

Ryusui let out a breath that almost sounded like a laugh. “That’s... nngh y-your fault...”

Sai’s focus shifted again as his rhythm steadied and his pace got faster again. He was not thinking anymore. Just reacting and following what felt right.

But Ryusui’s voice kept slipping, his words breaking apart between breaths.

“Sai... don’t slow down... just... keep that...”

Sai nodded faintly, even though he was not sure Ryusui could see it. His pace stayed steady for a few seconds longer, then picked up again, a little faster now. Ryusui reacted immediately, a sharper sound escaped him.

“Ah... yeah... like that...!”

Sai’s grip tightened against the mattress. Damn. Hearing him like this was something he never thought he would experience outside the fantasies he kept buried.

He thrust deeper, pulling out almost completely before thrusting again. Ryusui’s body reacted instantly, a louder cry coming out of him.

“Ahh...! F-fuck...!”

His words were gone now. Just sounds, broken sounds.

“Sai... oh yes... take me...!”

Sai sucked in a sharp breath. Those words in this voice went straight through him.

“...shit...”

His pace lost any control after that.

“Ah... nngh... fuck... yes...!”

Ryusui clung to him, pulled him closer, tighter. At some point, the rhythm stopped being something Sai controlled and turned into something he was chasing. The feeling was building too fast. Sai’s movements stuttered for a second. Ryusui noticed immediately.

“D-don’t slow...”

“I’m not.” Sai said, breath uneven.

But he was. Just slightly. Trying to hold it back.

“It’s just...I’m getting close.” He admitted, his voice lower now.

Ryusui’s reaction was instant and his grip tightened sharply.

“Don’t pull out!” He said, almost too quickly.

Sai blinked, thrown off. “...what?”

“I... mean it...!” Ryusui added, breath breaking. “Don’t...”

Sai hesitated. His thoughts tried to come back all at once.

“That’s going to make a mess inside.” He muttered.

Ryusui let out a shaky breath. “Don’t care.” He shook his head.

Sai stared at him for a second.

“...okay.”

That was all it took. His movements picked up again, faster now and less controlled, more driven by the pressure building inside him.

Ryusui’s reactions followed immediately, louder, more desperate.

Sai’s thoughts blurred again. All he could focus on was how good it felt. How Ryusui sounded. How he kept saying his name.

It was getting to him.

“Say my name again...” He muttered, almost without thinking.

“Ah... Sai...”

That pushed him over. Sai’s breath broke, his movements lost their rhythm for a second before he came, his body tensing hard.

“Shit...!”

He buried his face against Ryusui’s shoulder as the feeling hit him all at once. Ryusui’s reaction came right after. His body tensed, a louder sound broke out of him as the sensation hit him. His whole body was shaking as he followed. Sai kept moving through it, slower now but not stopping, riding out the last of it as both of them struggled to catch their breath again.

After a few moments, his movements finally stilled and he pulled back slowly. For a second, he just looked, then he ran a hand through Ryusui’s hair. Ryusui let out a weak, breathless laugh. Sai shifted again, then leaned down next to him and pulled him closer without really thinking about it. His hand moved to Ryusui’s back, with slow absent strokes. Ryusui did not resist. He leaned into it.

“...You’re shaking.” Sai muttered.

Ryusui huffed softly. “So are you.”

Then there was a quiet moment. They were both just breathing and enjoying the feeling of being close. Sai’s hand kept moving slowly over his back and his neck.

“That was...” He started, then stopped.

Ryusui tilted his head slightly. “Yeah?”

Sai exhaled quietly. How in hell should he describe that?

“...A lot.”

Ryusui smiled faintly, eyes half-lidded. “Yeah.” He said. “It was.”

“How are we even supposed to act tomorrow?” Sai muttered.

“Normally?” Ryusui suggested.

Sai stared at him.

“Ryu, we just had sex.”

“I’m aware!”

“Senku is going to notice. Gen too.” Sai mumbled.

Ryusui reached up without thinking and grabbed Sai’s hand. Sai blinked but didn’t pull back. Their fingers interlaced together.

“What are you doing?” Sai muttered.

Ryusui didn’t look away. “Just let me stay like that.”

“Okay.” After a second Sai’s grip tightened. His other hand still moved slowly over Ryusui’s back. For a moment, neither of them said anything. There was just the sounds of them breathing and the quiet regular creaks of the ship.

Ryusui shifted a little closer, his forehead brushed lightly against Sai’s shoulder. Sai noticed.

“You’re not letting go.”

The blonde huffed softly. “You don’t sound like you mind.”

“I don’t.”

Ryusui didn’t say something after that. His fingers squeezed where they were still interlaced. Sai’s hand slowed for a moment, then continued.

“...Ryu? You okay?” He asked after a bit.

Ryusui let out a small breath. “Yeah!”

It came too quick. Sai didn’t call it out immediately. He just kept tracing slow patterns along his back, feeling the tension that hadn’t fully left.

“You don’t sound like it.” He said eventually.

When Ryusui shifted again it was obvious he was a little restless.

“I said I’m fine.”

Sai exhaled quietly. “...you always say that.”

That got a weak reaction. Not quite a laugh. And for a second it seemed like Ryusui would leave it there. But then his grip tightened again.

“You’re going to leave again.” He said and his voice sounded lower now.

Sai blinked. “...what?”

Ryusui didn’t look up. His fingers curled tighter, almost like he was waiting for something.

“I bet when I wake up you will be gone.” He mumbled. “And then you will just... don’t talk about what happened.”

Sai stared at him for a second.

“Ryu.”

Ryusui breathed out slowly, visibly trying not to let the moment affect him too much.

“Forget it! I just-”

His voice caught and Sai felt it immediately.

“Hey.” He said, softer now. But Ryusui didn’t answer. His shoulders had tensed again. Sai pulled him a bit closer without thinking.

“Look at me.”

Ryusui didn’t at first. But then, after a second, he looked up. His eyes were teary and unfocused.

“I’m not going anywhere, okay?” Sai said.

For a second, Ryusui looked unexpectedly vulnerable. “You don’t know that.”

He moved his hand against Ryusui’s back a bit more deliberate now, like he needed the motion to think.

“Yes, I do.”

Ryusui huffed weakly and it felt off. “You say that now.”

Sai shook his head slightly. “No. I mean it, Ryu. I’m still here, right?”

Ryusui’s grip tightened again. “That doesn’t mean anything yet.” He hesitated, like he was choosing his next words carefully. “You always disappear when things get complicated.” Ryusui said and now it sounded more like an accusation. Sai flinched slightly at that.

“...you’re right.” Sai admitted after a second. “Usually I do. But I won’t.”

Ryusui’s jaw tightened.

“What makes this different?”

Sai didn’t answer immediately. His hand kept moving, grounding himself as much as him.

“You do.” He said finally.

Ryusui blinked as Sai exhaled quietly.

“...and what just happened.” He added. “That... wasn’t something I can just ignore and pretend it never happened.”

Ryusui’s still looked unsure.

“...you could.” He muttered.

Sai shook his head. “No.” That was fast and certain. Ryusui watched him closely now. Sai paused for a moment, then spoke anyway.

“I’m... not saying I have a plan.” He admitted. “I don’t have that figured out. This is... messy.”

Ryusui didn’t interrupt him.

“But I’m not leaving you over it.” Sai continued. “And I’m not just going to act like this didn’t matter either.” He added quickly. “That’s not... possible anymore.”

Ryusui swallowed.

“...why?”

Sai blinked. “What?”

“Why not?” Ryusui said, quieter now. “You’ve ignored worse things.”

Sai let out a small breath.

“Because I can still feel you. We crossed a line.” He said. “That’s not something I can just forget and go back to acting normal about.”

He paused.

“That kind of changes things.”

The silence stretched for a second.

“And you wouldn’t let me anyway.” He said, a bit softer.

Ryusui huffed weakly. “...no. I wouldn’t.”

Sai almost smiled at that, just barely.

“See? Good.”

Ryusui’s shoulders finally eased a little.

“Okay.” He murmured, quieter now.

Sai’s hand moved up to his hair again, brushing through it gently. They stayed like that. Closer than before.

“You need sleep.” Sai muttered after a while. “You’ll be unbearable tomorrow if you’re too tired.”

Ryusui laughed quietly. “Can I stay like this?”

Sai’s chest tightened unexpectedly at how casually Ryusui asked that.

“Yes.”

Ryusui was quiet for a second before asking softly “You planning to still be here in the morning? When I wake up?”

“Also yes.”

Ryusui looked far too happy hearing that.

“Mhm.” Ryusui’s voice softened. “Can I keep this version of you?”

Sai clicked his tongue quietly. “Don’t make it weird.”

Ryusui relaxed fully against him, warm and content in a way Sai still didn’t quite know how to deal with. He stared at the ceiling.

This was going to become complicated.

Probably very complicated.

But...

...

Was it?

Lying here now, listening to Ryusui breathe softly beside him, Sai found himself thinking something strange.

Maybe allowing these feelings wouldn’t actually be as terrible as he kept expecting.

Tonight had felt strangely easy.

Scary, yes. New in ways he still wasn’t ready to acknowledge. But not wrong.

And Ryusui was here too, carrying the same feelings.

Maybe that changed things. That did make the future feel a little less frightening.

And figuring this out together would feel less impossible than doing it alone.