Author Notes: Reading pixiv fic has made me realised that sex with Jin has the potential to be very...interesting. I chickened out from actually writing about them having sex with Jin's side effect involved though orz Maybe someday.
Jin has a bad habit of hiding his face when they have sex. It doesn't matter what position they're in, or where they are, or even if they're just kissing. Jin never looks at him if he can help it.
"I don't want to see what you're going to do next while we're having sex, Tachikawa-san," Jin had said, a slight flush of embarrassment on his cheeks that didn't suit him at all.
Tachikawa often gets told that he needs to think about the things he says more, so he wasn't exactly surprised to receive a kick from Jin after he mentioned how weird it was to see him blush. What surprised him was what Jin said after that.
"Maybe that's why I don't want you to see me when we have sex either." Jin's voice had been dry. Even Tachikawa had managed to realise that that was Jin being vulnerable.
"No," Kazama says brusquely, interrupting Tachikawa's recollections. "People don't just 'understand' Jin. He doesn't let them do that. Be more aware of how much of himself he lets you see, and how much you manage to see all by yourself compared to everyone else. Also, stop talking about your sex habits and start working on this report. I thought you wanted me to help you with your university homework."
"I do want your help with that!" Tachikawa says hastily, picking up his pen again and putting it towards the paper spread out in front of him. It doesn't last. "You really think Jin lets me in more than everyone else?"
Kazama sighs heavily, putting down his own pen. "I think he realises, because he's not dumb, that you already see so much of him anyway, he might as well let you in all the way. That's just the kind of twisted thinking Jin is fond of. You already knew more about the way he works and the way he thinks than anyone else even before the two of you started dating anyway."
"Are we dating?" Tachikawa asks morosely, leaning forward until his forehead thuds down onto the table. "I think we're just having sex."
"It's not like you to be so indecisive," Kazama offers desperately. He doesn't need Jin's side effect to know that the chances of any schoolwork getting done are vanishing as they talk.
Tachikawa blinks at him. "You're right." A determined expression spreads on his face. "You are absolutely right. Who cares what Jin thinks. I'm going to undermine that stupid foresight of his if it's the last thing I do." Ignoring both Kazama's blank look of surprise and the schoolwork spread out on the table in front him, Tachikawa stands resolutely and strides out the door.
Left behind in one of the tiny meeting rooms that characterised the administration part of Border's main base, Kazama stares at the door dazedly. "That's what you were worried about?" He looks down at the mess spread out in front of them, then starts tidying. If Tachikawa finds himself with not enough marks to pass his classes, that's his problem. But maybe he'll stop trying to talk about his sex life to Kazama now.
The night starts out like any night when they have sex. Jin's face screwed shut as they kiss, the strength with which he grabs at Tachikawa's shoulders belying his desperation. When they finally reach the bed, their naked hips rubbing desperately together, Jin automatically pulls away and turns his back to Tachikawa – face hiding in the sheets. It's the position they always have sex in, Jin's back to Tachikawa so that he can't see anything. Not the future, not the past, not the present.
But this time, Tachikawa isn't going to let him. He rubs at the hard heat between Jin's legs, pulling at his arm once he's caught Jin off his guard.
"Tachikawa…san?" Jin asks breathlessly, eyes flickering from Tachikawa to the air behind him.
"Look at me," Tachikawa says, working Jin open with his fingers. "Look at me. I will make sure the future you see does not happen, you know I will. I promised you I will."
"Ah," Jin sighs, letting Tachikawa in. "Tachikawa-san."
"Look at me," Tachikawa says again, bending over Jin as their bodies slot together.
Their eyes meet for the first time that night. "Tachikawa-san," Jin says, sounding like he's crying even though he isn't. Tachikawa can tell.
"Look at me, Jin," Tachikawa repeats, again and again and again. Their bodies moving in tandem, the kind of synchronisation that Tachikawa knows is only possible because of how much they've fought – with each other, against each other, it's all the same. "Look at me."
Jin laughs, his Adam's apple bobbing; he does not look away from Tachikawa's eyes. Not until they are done, and Tachikawa has collapsed heavily beside him. "What brought this on, Tachikawa-san?"
Tachikawa pants heavily. "I never really thought about what we're doing before. But having sex together, that's kind of a big deal, isn't it? It's like our fights. I mean, I can't overturn your foresight if you're not using it, can I?"
"What happened to your stamina, old man?" Jin says instead, but Tachikawa can see the red tainting Jin's ear.
"Well?" Tachikawa asks. "Did you see what I was going to do? Did I manage to go against what you saw?"
"Why must you be so cruel to me, Tachikawa-san?" Jin says in response. He turns around so that their eyes meet again.
"I'm not cruel, I just don't care if you're embarrassed," Tachikawa says, pulling Jin into his arms – their faces close enough for their noses to touch. Jin is looking at him; whether it's the him of the past or the him of the future, Tachikawa doesn't know. But maybe, if he's lucky, Jin is seeing the him of the present.
"You never do. Even though I'm an elite by my talents." Jin pouts.
Tachikawa snorts. "An elite that hasn't beaten me with a regular trigger yet."
"Now those are fighting words." Jin smirks. Now Tachikawa knows Jin's looking at the present.
"Wanna go?" Tachikawa asks eagerly, sitting up.
"Or…we can stay here instead," Jin drawls out, grabbing his phone from the bedside table and showing Tachikawa the time on the screen.
"It's only one in the morning. That's plenty of time for a battle and then more sex later!"
"Don't you have a report due tomorrow afternoon?" Jin points out mercilessly.
"Ah," The blood drains from Tachikawa's face as he remembers the untouched schoolwork he had left with Kazama earlier that day.
"Go to sleep, Tachikawa-san. You'll need to wake up early tomorrow to finish your report." Jin sighs, slumping down on the bed. "My side effect tells me so."