It's like coming home, Kaito thinks, but to a home that's been changing as much as he has, and he's not quite sure how they fit together anymore, or if they fit at all.

When Chris had left him, he had steeled his heart and told himself to move on, but it's only now that he sees how lonely he had been. How much he had missed him. He doesn't like it, how achingly full his heart is, the longing that's as bitter as it is sweet. It's almost like it was back then, when he first started to realize he was in love with him, but worse, because back then it had seemed silly and unattainable, just a crush that would never come to anything, but now he's had him and lost him and still has to work with him all day long.

They haven't talked about what they used to be. Kaito doesn't know if they ever will. Neither of them is particularly good at talking about feelings. It's sometimes a blessing, but right now it's not, because Kaito can't help but wonder what's going on behind Chris' placid smiles, whether he thinks about the old days too or regrets even the good things that have happened between them.

They tack their graphs and charts and readouts to the walls, and cover their desks in books on everything from electrical circuits to theoretical physics. It's comfortable, doing research. It's something Kaito knows how to deal with. They put the project between them and address each other through it—Good morning Kaito, shall we focus on the stabilizer today? Chris, can you pass me that book?

Chris has picked up some new habits since Kaito last saw him. He drums his fingers and shuffles papers and makes small irritated huffs when something is frustrating him. Other habits are older, ones Kaito remembers from back then. The way he frowns when he's thinking. The absentminded way he tucks his hair behind his ear. How he plays with the corner of a page when he's reading.

What are you thinking, Chris? Kaito is thinking about their first kiss, the one after Kaito had awakened his instinct as a duelist. They had been triumphant that day, kids who had taken the leap into a huge discovery. Chris had taken Kaito to his room, chattering brightly about what this meant for the future of their research, and somehow he had ended up inside, sitting on Kaito's bed, and before Kaito knew it their knees were touching and their hands brushed each other and he was pretty sure he was blushing and Chris had a hand on his face, running a thumb over a bruise he had gotten during one of their many duels, and he murmured something about how incredible he had been, how strong he was, and Kaito blushed harder and started to say it was nothing special and then Chris kissed him, and Kaito had no idea what to do except gape.

"I'm sorry," Chris had said then, looking like he hadn't expected it himself, "That was—inappropriate, and I—"

"No," said Kaito, and kissed him back, and their mouths were misaligned at first, but then Chris shifted into it and their fumbling hands found each other and Kaito was pretty sure he was terrible at this but it didn't matter at all because his heart was beating so fast it felt like it was about to explode.

That was then, though, and this is now. Kaito wonders if Chris has been with anyone since then. He doesn't think there's anyone now—at least, Chris hasn't mentioned anyone—but it's been years and Chris is handsome and anyone would want him, it's only natural.

It's not like it matters, he tells himself, a little disgusted with how much he seems tocare.

(It still makes something twist in his chest, imagining.)

At the end of their first day they unroll their sleeping bags and spread them on the floor a few feet apart. Chris falls asleep first, and Kaito listens to his soft breathing and remembers the few times they had shared a bed. He had buried his face against his shoulder and smelled the clean scent of soap and shampoo and felt like an adult, like they were more than just two kids who had no idea what they were doing, like they were a real couple. Even thinking the word had sent something warm and happy and squirmy down his spine.

God, he had been so naive then. He had imagined they would be together forever, that once he was old enough they would move in together and he would have Chris' smiles and Chris' encouragement and Chris, and everything would always be simple.

He growls in frustration. Why is he acting like a lovestruck child? He's eighteen years old now. He's dueled beings from three worlds, he's taken Numbers and souls too, he's building a goddamn interdimensional portal. He's not the kid he used to be. He clenches at the fabric of his sleeping bag. He's not.

He gets up and sits in the other room with a lamp on low, poring over books until he's too tired to understand what he's reading. He slips back into his sleeping bag and wakes up a few bleary hours later, and does that the next night too, and the night after that. He's starting to run on empty, and he prefers it that way.

Five nights later, Chris catches him at some obscene hour of the night, taking notes that he isn't sure he'll understand in the morning.

"It's late, Kaito," he says, more of a question than a statement.

"I couldn't sleep," Kaito says, which is true. "I figured I might as well do something productive. We don't have a lot of time, in case you forgot—"

"Mm, really? Have you found anything new?"

Not really, because half the exercise is him trying pointedly not to think of everything Chris had said to them that day. He's silent.

Chris' face softens. "You need to be at your best, Kaito. Working all night doesn't mean much if you're about to collapse at any moment."

"I'm not about to collapse—"

"I know you better than that," says Chris, and it's the first time since they came here that either of them has acknowledged that. "You need to stop working yourself to exhaustion."

Kaito disagrees, but Chris refuses to go back to sleep until Kaito is tucked snugly back in his sleeping bag, so after that Kaito spends his nights lying awake and wondering.

—

One day they solve an impasse, one of the coding snarls that seemed impossible at first, and Chris wants to go outside to celebrate. "We deserve some fresh air," he says. Kaito doesn't particularly like the snow, but it's hard not to be a little happy, especially with Chris smiling like that, so they put on their coats and step out into the cold air. They're greeted with a stinging wind, one that seems to pass right through Kaito, and he finds himself wishing he had brought better clothing. Chris' face is already pinkening, snowflakes catching in his hair and eyelashes.

"It feels good, doesn't it?" says Chris. "To really be making progress. No one's ever done this before; it's incredible, when you think about what we've already accomplished."

A pang of nostalgia hits Kaito, and right then it's unbearable, with Chris smiling and handsome and completely fucking oblivious. "You said something like that back then," he says.

"Back…?"

"When you kissed me for the first time." It's terribly ill-advised, but Kaito is sick of sitting around. He's sick of this gnawing in his heart, these stupid flutters when Chris praises him, the memories that won't stop taunting him, the dreams about what he tries so hard to ignore. If you won't say anything, I will. One way or another, let's put this behind us. If we're done, then let me know.

He steps forward, meaning to say something, anything, but somehow his intent gets jumbled up between his brain and body, and instead he grabs Chris by the scarf and yanks him forward and kisses him. His breath is hot. He doesn't move. Kaito doesn't move either, and for a moment it's just two mouths on each other with neither of their owners sure what exactly is going on.

Then Kaito pulls back a little. Not far enough that they can look each other in the eye. Chris is warm, and anyway, he's not sure he wants to see his face right now. Not after…that.

"Kaito," says Chris quietly. "What did you mean by that?"

Kaito thought it was pretty clear what he meant by that, but as he opens his mouth he realizes he doesn't know, not really. I missed you. I miss being with you. I loved you then and I love you now. All of those things are true, but he doesn't know if he can say them yet. "I still want to be with you," he says finally, stiltedly. "If you. Want that too." He thinks Chris breathes in at that, but it's hard to tell over the pounding of his heart and the winds gusting at the snow.

"Do you really mean that?" says Chris, and Kaito allows himself to hope a little, because Chris sounds hopeful himself."You want to—to try again? To start over?"

Kaito pulls back enough to look him in the eye, but he's still close enough that his hands are on Chris' shoulders. His face is red—from the cold or blushing or both—and the smile on his face is one Kaito hasn't seen in a long time.

"We don't have to start over," Kaito says. "Where we left off is fine. I just—Chris, I—"

He doesn't know what else to say, but luckily Chris understands. "I'm so happy to hear that, Kaito," he says, eyes bright. "You know, I—"

Kaito doesn't hear what he says next, because a particularly strong wind takes the opportunity to shower them with a flurry of icy flakes. The winds are getting rough, Kaito realizes; he hadn't even noticed.

"Let's take this inside," says Chris, laughing. He laces his hand through Kaito's, and they walk back inside together. Kaito moves toward the fireplace, but Chris doesn't let go of his hand, and pulls him to the other side of the room.

"It's cold," Kaito protests.

"We'll share body heat." It's rare for Chris to be this forward, and Kaito follows, wondering vaguely if this is a dream he's about to wake up from. If it is, it's unbelievably cruel.

They don't have couches, but they have computer chairs, and Chris sits in one and pulls Kaito into his lap. It's a small chair, and they're curled close, Kaito straddling Chris' hips and leaning against his chest. It's not a comfortable position, but Kaito could stay like this forever, regardless—that's what he's thinking when Chris wraps his arms around him and buries his face against him, and Kaito feels every bit of tension leave his body in one contented sigh.

"I didn't want to say anything," Chris says finally. "After what I did to you. I thought I had no right—"

"Idiot," Kaito fondly, but it's an odd sort of relief, knowing that Chris' heart had been aching too. It satisfies some sort of primal possessiveness he hadn't quite known he had.

He leans his head against Chris' chest; it's completely undignified, but he finds he can't quite bring himself to care. They stay like that for a moment, listening to each other breathing, and then Chris pulls back and runs his fingers over Kaito's cheek, his jaw, his lips. The look in his eyes is so tender it hurts a little.

"You're cold," he says softly.

"Your fault." Then, a bit more daringly, "You should take responsibility." Kaito kisses him again, more languidly this time, and Chris' lips are so warm he doesn't want to pull away. Chris' hand finds the small of his back, and Kaito wraps his arms around his shoulders and plays with his hair.

Stupid, Kaito thinks they were both so stupid, but he was probably the stupidest. If he had done something earlier they could have had this all along, every day.

He has what he wants right in from of him, and he's feeling greedy today. He arches against him, grinding his hips down, and Chris makes a muffled moan.

"K…Kaito…" is all he manages.

"Aerobic activity will warm us up, right?" Kaito murmurs. "In this climate it's important to keep our body temperatures up one way or another. Some studies have shown sex improves focus and concentration, you know."

He hasn't stopped rocking his hips against Chris, and Chris is starting to breathe harder, clutching at the back of Kaito's shirt like someone who's not about to let go anytime soon. Kaito likes seeing him like this, completely uncomposed, and it makes him move against him even more urgently.

"Only you would seduce me with studies, Kaito," Chris says, tense and smiling and so, so hard.

It's too cold to undress, but it's fine this way. Kaito unbuckles Chris' pants and palms his cock, and Chris whimpers needily at the touch. One part of Kaito's mind says that this is too fast, they barely just reinitiated this, they still don't know quite where they stand and anyway isn't this a distraction too—but the other part says it's been years since he's had Chris, and he'll be damned if he's not going to make up for lost time.

—

Days are the same, mostly. They wake up and eat a breakfast of cold biscuits and work until their necks are stiff and their backs are aching, and then work more. They talk about the project, but they're quiet a lot of the time too, each focused on his own tasks. The difference, Kaito thinks, is that the silence is warmer. When their hands brush together they linger a little, and when they make eye contact Chris smiles at him. Sometimes Chris puts a hand on his back when he passes by, just for a moment. They sit shoulder-to-shoulder when they read and it's comfortable, so comfortable Kaito can't believe it took them this long to find it again.

They zip their sleeping bags together and share body heat every night, curled close together. Some mornings Kaito wakes up and finds they've rolled apart, but other mornings he wakes up with Chris' chin against his shoulder, or Chris' arm thrown over him, or their legs entwined uncomfortably.

They make love again and again, once more in the chair and once in the shower and once on a desk, with Kaito's shoulderblades digging into the countertop. Sex is good for the mind, he tells himself, it stimulates blood flow and decreases stress, he's not being selfish here, it's a simple matter of productivity. He starts saying something like that to Chris once, when he's pinned against a wall with Chris' mouth on his neck, and Chris just laughs lightly.

"Why do you think you need to justify this to me?" he asks, and Kaito starts to think about that, but then Chris' knee is between his and everything fizzles out, and maybe right now he can take a break from thinking, after all.