I wrote SaiNaru, and I hardly like Sai. But I'm a sucker for angst, so yeah...
I don't own Naruto...
The first time Naruto saw Sai he was forcibly reminded of Sasuke. The way they both won't show their emotions, the 'nicknames', how both of them will never goddamn smile. But Naruto knows that Sai isn't Sasuke: they're far too different.
They both never showed any emotion, except that Sai claims to have no emotions, whereas Sasuke, Naruto knows, has them.
Sasuke has shown many emotions in front of Naruto--anger, as he attacked Naruto on top of that hospital, and then later, at that waterfall, but also love as he whispered sweet things in Naruto's ear, and protected him even at the near cost of his own life. Sai has shown nothing but cool indifference and a fondness for Naruto's penis. No, Naruto knows that Sasuke and Sai aren't the same.
They both called Naruto names that questioned his worth--Sasuke with dead last, and absolute moron, and scaredy cat; Sai with no-penis and other such things.
Except Sasuke called them in a 'pet-name' sort of way, they were done because it accurately described Naruto, and because Sasuke didn't like to say his name. But Sasuke used to call him other things, too. Sweet things like koishii and Naru-chan, even if it was only sometimes at night. Sai called Naruto names because he's read in a book, somewhere, that nicknames were a good way to get along with someone. Naruto doesn't know if Sai says them because he thinks it true, but he does know he doesn't say them in the same way Sasuke did. Yes, Naruto knows that Sai and Sasuke are two very different people.
They both hardly ever smiled, Sasuke and Sai. But Naruto knows that that isn't true. He's seen Sasuke smile at him asking if he was 'alright Mr. Scaredy cat', or on missions when Naruto did something particulary amusing (stupid) and Sasuke found it funny, or at night when he used to just hold him and smile. Sai has only smiled at Naruto once, and even then he insulted him. Other than that he has only looked at Naruto with a leer or a smirk, and it's worse than Sasuke.
Naruto knows they're not the same people. He understands that. But as Sai presses Naruto against the futon placing a bruising column of kisses down Naruto's neck, his artists hands quickly stripping Naruto of his black and orange jacket, and then his shirt, Naruto knows it's not Sasuke.
But if he turns his face and squeezes his eyes shut, he can pretend that it's Sasuke running his tongue over Naruto's stomach and seal, and that it's Sasuke touching him in that way. And as Naruto arches against the bed, making fists in the sheets he can pretend that it's Sasuke making him feel like this. Except that Sai doesn't touch him in the same way that Sasuke does--did.
And, in the end, Naruto knows that Sai isn't Sasuke, he's a constant reminder of everything Naruto's lost.
Please review, tell me how crazy I am.