Does fanfic mean fan fiction? Sorry, not up on the terminology. In any case, I love me some fan fiction. The various Starwars spoofs, Red V. Blue (machina fan fiction), that fan Halo movie that was supposed to come out that I just reminded myself about with this post that I should check right now to see if I can get it.
I think that as long as it is an original story and/or a spoof, it should be fair use. I know some of it is even encouraged by the copyright holders. Lucas had contests for Starwars fan films. Microsoft/bungee encouraged Red V. Blue. Basically, as long as it isn't being passed off as the real deal, I don't see much of an issue with it and think it's good free advertisement for the copyright holders as well.
There's some naughty Anime out there that might be questionable.......uh....I....uhmm...heard that from a friend of course.