The more mature a fic can be, the better. As long as it's not overdone, I'm perfectly fine with reading the occasional sex scene, or whatever the hell may come. I don't particularily read a fic just for the awesome sex scenes, or anything, but it can definately add to a fic, showing a certain unbreakable bond between two characters.
As long as there isn't random banging every chapter, I'm perfectly okay with it.
As far as violence goes: the more brutal, the better.
Adieu,
Zak Hunter