i personally am a big fan of Denial Kakashi where after he meets Tobi for the first time and sees That Eye, he knows. he knows but he can't wrap his head around it. it's inconceivable and insane and should not be possible but plenty of insane, unreal things have happened to him before and his life is one big cosmic joke so why couldn't it be true? after that day, he's plagued with this feeling—guilt or something else, he's not quite sure—and it won't go away and it's making him even more paranoid because what if other people can tell something's up with him, that he thinks his dead teammate/best friend/crush might actually be alive and be a part of the akatsuki. it's so insane and so unreal and so unfair that it makes him sick most nights and he pleads with any being that is alive that it's not true, that he was seeing things. but kakashi knows his eye and it was like something clicked when he saw that masked man's eye and he knows it's his eye's other half. he can just tell.
so he goes between wanting to believe he's crazy and wanting to believe it's anyone but obito but if it is someone else, that means obito's other eye was stolen and that means someone played with his remains but that's also improbable because obito was a nobody uchiha; there were plenty others more notable and feared and known than obito. but if someone had, that's even worse because the eye would be in the possession of an other and for that, the other will pay with his life. but kakashi knows, deep in the gaping wounds of his still healing grief, it's obito.
but he can't say it. he won't say it. and he hopes no one looks at him funny because he feels stitched together in a grotesque caricature of himself that'll come apart at the seems if someone asks 'are you okay'. some nights he feels young. he's sweaty and his hands won't stop casting. the lightning bolt scars that wind across his arm and down his wrist to the very tips of his fingers burn and his joints creak. he can't sleep else he be plagued with visions of neverending tunnels, the scent of petrichor, warm slippery blood between his fingers and sheathing his arm.
some mornings he wakes up and half his body feels fake, like mush and not his at all. imagines of obito half-dead under that fucking boulder flash in the empty spaces of his mind and he can't take it. he tries to put it all out of his head, he tries to push it away and tell himself there's more to focus on like naruto and sakura, and even that sai kid and tenzo too. he's yamato know or whatever but kakashi doesn't care because he has another friend back, one who knows some of the nastiest sides of him.
he can push it all away, he forget about it for a little but the nights he has alone are all but soaked in blood and memories. and he knows it's obito, he knows he should say something but he can't. it's like the words are stolen from his mouth as soon as he opens it in a silent thievery. he tries to tell himself that he'll say something but he won't. he won't because he can't because it's a betrayal of everything he knows. of obito the boy he once knew, of obito who he's still loyal too, of himself for giving up a treasured comrade no matter what deeds he's done. it's not something he can do.
and when the mask finally breaks, kakashi whispers his name in disbelief, except it's not disbelief. it's horror and sorrow and a beg for forgiveness all wrapped up in one name. his eye's other half, the split of his soul, the very wounds of his chest are in front of him in the shape of a boy he used to know.
so yeah, i believe kakashi knew it was obito all along but boy is he good at Denial.
