Their existence together was good - well, not good, but tolerable. Sai was even worse at human interaction than Sasuke was, but that suited Sasuke just fine - it meant that Sai was always brutally honest. Sasuke was through with people lying to him. And Sai didn't expect Sasuke to feel, he only expected him to be there - it didn't matter that the only reason Sai didn't pester him for sweet words was that he didn't know they should exist. That he didn't know it was odd for you to wake alone when you'd not fallen asleep that way. But at the same time, Sai didn't have to deal with so many things he couldn't understand from Sasuke - because Sasuke was like him. Sai didn't have to hear 'I love you' and honestly not know how to respond, he didn't have to worry about hurting by telling the truth.
"How the hell does an ANBU black-ops stay as innocent as you?" Sasuke muttered over his breakfast one day as he watched Sai squirting chocolate syrup on his toast in a smile that matched the one on his face.
"Innocent?" Sai asked, automatically turning the bottle right-side up and holding it away from his toast so as not to spoil his crooked picture. "How am I innocent? You watched me remove a man's organs over the course of five hours yesterday without knocking him unconscious. That's not innocence." He looked honestly confused as he brought the container to his mouth to suck on it like a baby bottle, and Sasuke nearly gagged.
"That shit'll ruin your teeth," Sasuke growled.
Sai smiled around the bottle. "It tastes good. You should try some."
Sasuke frowned as he stood up, "Quit drinking that, we've got a mission later and I don't want to deal with you on a sugar high this early in the morning," and moved to take the bottle from Sai but the other boy twisted out of his reach without removing the bottle from his mouth.
A few moments of chasing him around the kitchen and Sasuke managed to snatch the bottle from his hands, only to find Sai's lips against his own. He was surprised for half an instant, not long enough for anyone to register, but Sai noticed anyway and chuckled into the kiss as he steered Sasuke across the kitchen until he was pinned against a wall. Their hips ground together slightly, and Sasuke tasted chocolate as their tongues twined with one another.
An hour later they were late to meet their teams and were washing dark stickiness off each other in the shower.
Three nights later, Sai snuck past the traps of Sasuke's house with hardly a flicker of extra movement to deactivate and reset them. He paused in the doorway of Sasuke's room, knowing Sasuke was watching him despite the fact the Uchiha was by all appearances asleep.
"Take off your shoes."
Sai slipped off his shoes and set them to the side of Sasuke's doorway. It was the closest to asking permission to enter and being granted it; if Sasuke told him to go away, he would. But if he snapped at him to take off his shoes, or stop dripping water on the floor, or to clean the blood off his face - that meant it was all right for him to be there. Sasuke didn't move as Sai climbed onto the bed, just waited for Sai to arrange himself around him and bury his nose into the crook of Sasuke's neck.
"Are you only this stupid around me?" Sasuke said after a moment without turning toward him. He could feel Sai's smile tickling the base of his neck.
"What do you mean?" A small kiss accompanied the words, set at the short, bristly hair halfway down Sasuke's neck.
"You don't smile around anyone else. Except that weird forced one, or if you're talking about your brother."
Sai pushed himself up, sitting so he could look down at Sasuke. "I smile around you?"
"Yeah, and you're stupid and childish. You're petty and touchy-feely and you...you..." he trailed off. Sai was looking at him in honest confusion, something resembling a hint of worry slipping into his expression. Sasuke rolled half onto his back to look up at him, mind catalogueing the location of every weapon and potential weapon in the room as his body retained its sleepy posture. The Sai Sasuke knew would never have let his emotions loose for an instant, but this Sai, the one that forgot to take off his shoes, the one who drank honey and chocolate syrup, the one who kissed Sasuke as if it were only natural...this was a different Sai.
His Sai. Maybe even the real one that had never been allowed to exist.
Because he'd realized as he was mentally locating all his weapons - some were hidden behind pictures. Nameless pictures of flowers and cats and people, some pinned to the wall by tacks or shuriken, others lying in piles on the floor alongside dirty clothes and bottles of ink. And there was that one picture, the one under a mat on the desk - to protect the desk from ink stains, of course, not the picture - done in quick, messy brush strokes with nothing more than watered-down black ink on cheap paper. The one he'd called 'Sasuke' before crumpling it up and throwing it in the trash.
Something clicked in Sasuke's mind as he understood the look on Sai's face, and he reached up to twist his fingers in Sai's hair and pull him down into a kiss. "I'm not telling you to stop," he said quietly when their lips parted, not meeting Sai's eyes.
They didn't want love or expect it, and knew full well that the day would come when one was gone in the morning and didn't come back. But in the meantime, they took comfort in the quiet warmth of one another's arms as they fell asleep.