Hmm.. probably Kyon, from Haruhi no Yuutsu.
I use that character to repesent myself a lot, through forum theme/avatars, etc. I'm not even that big of a Haruhi fan, actually.. I never really got huge into the series, but it was good. Alot of my friends used to call me Sasuke when they were real big into Naruto.. :/ but eh. I'm not emo, or hell bent on revenge. So.. Kyon wins over Sasuke.
I'm calm most of the time, but also when I do actually get a bit more lively, then that side of me is probably more like Hige from Wolf's Rain. xD;