I'm going to get out some (sns meta) thoughts that I've had percolating for a while now and have expressed on discord here and there. I don't know if these will ever make it into a fic or not. RE: Sasuke characterization
One of the things I find kind of frustrating about the way fans characterize Sasuke and SNS is that I keep seeing memes and fanworks that sort of imply Sasuke feels he is unloveable in some way? As if, his issues with accepting Naruto's affection in Shippuden stem from some fundamental belief he has that he doesn't deserve to be loved that way, so he has to push Naruto away. And to me this is just.... so confusing? Like it's wrong in a super obvious sense, but also I'm not quite sure where it comes from beyond a desire by a subset of fans to project their own insecurities about their self-worth onto sasuke, but I feel like it's more widespread than even that.
Most generously, I see one particular panel used as "evidence" of this characterization - the panel/page where Sasuke asks what "friend" means to Naruto and he replies "when I see you take things on by yourself, I hurt." Sasuke's response is pure surprise, and I can get how that's easy to read as "oh wow you LOVE me and don't just think of me as a friend?" From there it's usually extrapolated by fans as Sasuke having some hangup over believing his own love was painfully unrequited and that's why he was acting out, which is an undercurrent to his revenge mission, but I think it's such a misread. Idk it's so boring/dumb to read it as "Sasuke is so gay and Naruto is so hetero and oblivious he had to become a terrorist about it!" pls
Sasuke isn't surprised in that panel because he is realizing that Naruto actually loves him romantically when he thought he wasn't worth loving, I think the key lies in Naruto's phrasing - he *hurts.* Loving Sasuke hurts, but he does it anyway. That's what Sasuke has been running away from this whole time, isn't it? This idea that his love for Naruto or for his team could be used to hurt him because his love for his family/brother had already been used to hurt him - that's the fundamental drive of his character. Sasuke is afraid of the pain of love, either the pain from losing someone or the pain caused when that love is wielded like a weapon against him. It's not a question of whether or not he's deserving of love - he actively tries to be as unloveable as possible because the more someone loves him, the more likely he is to fall into reciprocity. It's easy when he just has fangirls who don't truly know him, but that's not what it's like with Naruto.
Meanwhile, here is Naruto, laying in a pool of his own blood, smiling and admitting that loving Sasuke hurts, but he shows no hesitation, no sign of backing down. Sasuke has given him every reason to turn his back on him, to close himself off, and Naruto never does. He just bleeds and bleeds and exists with his heart on his sleeve like that, not even scared to admit it. I think that scares and amazes Sasuke, which accounts for his expression in that scene. That's why Sasuke loses. He thinks by killing all of the soft parts of him that he can grow past feelings as juvenile as fear, but here's Naruto with all of this terror at losing him, losing his village, his friends, but he doesn't flinch. He just accepts the pain as part of living, which is what Sasuke ultimately realizes he needs to do. I think it's actually way more interesting a read than Sasuke just being surprised someone loves him so much.
It's not that I don't think Sasuke can't have self-esteem issues. He's insecure to a fault in part 1 and it's what drives him away from the village. He fears not being the best, of falling behind to someone he sees as a sort of protegee. As much as SNS fans despise the mention of any kind of "brotherly" bond I genuinely think that's what they have in part 1, even if it's twisted. I think them forming some kind of earned brotherhood is what makes the end of part 1 impactful, like Sasuke kind of, in miniature, does to Naruto exactly what Itachi did to him: a fundamental betrayal, violence, the severing of his most important bond which tears away any semblance of family. I think it's the transformation of this relationship (they no longer see each other as protegee/brother) in part 2 which actually opens the bond up to becoming something more romantic. And then, after part 2, I definitely think Sasuke would struggle with guilt and whether or not he feels worthy of Naruto's love, but there's never really a question of whether or not he has it (whether or not that love is romantic is obviously another question entirely). But I dunno, I can't abide any characterization where Sasuke mopes around feeling sorry for himself all the time. I also think any guilt he would feel after shippuden is purely restricted to Naruto - there is just no way I see his "redemption journey" as him actually feeling sorry for threatening the kage. His participating in Orochimaru's human experimentation is another issue - one I haven't made up my mind on. I think Sasuke would come to regret parts of it, but I also don't see him beating himself up over it constantly.
Anyway, these are just the ramblings of someone procrastinating on writing, but they're things I think fundamentally inform how I write and interpret Sasuke in canonverse fics.