•It takes a lonnnnng time. Even if Kakashi knows he loves them, even if he’s sure of it and there’s no doubt in his mind, it still takes a while. He knows saying it too early on can be a little unsettling, so he just waits for the right time
•It has to be after something. Like, something needs to prompt him to do it. Maybe they had a fight, and while he’s making it up to his s/o, he says it. Or after he’s been on a mission for a long time, he comes home, settles down with them in bed and relaxes, and it just slips out
•If it’s going to be a casual affair, it might as well be while they’re lounging around together on the couch or something. Just after a long day, after he’s feeling particularly happy, he just says it “I love you”
•He only worries about how they’ll respond after he says it, and there’s a fleeting moment where his heart skips a beat because shit, did I really just say that?
•It all depends on their reaction, and the delay of their reaction, actually. If they’re silent for a while, Kakashi quickly mediates the confession with a, “What? Was that too fast?” It sounds very much as it was intended to be: like a joke. But on the inside he’s like damn it… it probably was too fast, wasn’t it?
•Hopefully they’ll chuckle, look at him with a genuine smile on their face, and reciprocate the confession. He doesn’t even mind if they tease him a little, something like “Is that true? You love me, Kakashi Hatake?”
•As long as he doesn’t make a fool of himself, and they say it back and don’t leave him hanging, then it’s fine. He calms down. Mission accomplished
•Actually, he won’t mind if they don’t say it back. He knows they might not be ready and doesn’t want to push them. He can wait if he needs to