I read a good fic back in the day about him seeking revenge on Cloud for not protecting her. It ended up being TsengxElena in the end because she was helping him get over his anger but it was still sweet.
Link please.
I can't remember if I've posted this before on this forum, but since I don't care about repeating myself, here's my take on the infamous helicopter slap:
Tseng has known Aerith for a long time - exact length of time is unspecified, but certainly longer than the 48 hours (max) that she's known Cloud and Co. During that time he has both wooed her to return to Shinra, and protected her from Shinra, since it's clear that the Turks are making no great efforts to bring her in, and even seem to have some kind of understanding with her. Reno knows where she lives, yet after the Church incident he just buggers off, presumably to report (yet another) failure to capture her.
AVALANCHE , meanwhile, have blown up several reactors, with considerable loss of life, and have presumably been causing trouble and suffering for a while before that. [I don't mean to imply by this that Shinra are the good guys. No government is ever the good guy.]
So when Tseng discovers that his precious last of the Cetras has got all pally with a bunch of terrorists she hardly knows, he is, quite understandly, livid, both on a personal level (it's a huge rejection of everything he's done for her) and at Aerith's own dangerous stupidity - or so it would seem to him. When she pushes it too far, he lashes out at her - to shut her up, to warn her, to teach her a lesson, because he can't control himself, and because he is a man who makes his living by violence. That doesn't make it OK to hit her,
obviously. Probably doesn't make it forgiveable. But it does make it understandable, I think. It's not as if he's randomly punching her because he gets a kick out of abusing women. He's infuriated by her naive folly. I'd be really surprised if there's anyone who has never felt (though of course resisted) the urge to land one on the face of someone they love who's done something incredibly stupid.
I have confined myself to supporting my argument with evidence from the OG. Evidence from the Compilation only makes it stronger.
The defence rests.