I think it depends on my audience, which is mostly dictated by fandom, because I know most of the FMA people don't read my, say, Alias fic, and the Harry Potter people don't read my FMA. And the Batman Begins fandom is so tiny, I doubt many people read that. So yeah, I write far more in a story-teller vein when I write FMA, but when I write Batman Begins, it's pretty much entirely for my own benefit, because I don't expect to get many readers (whether or not that's true). I write what I want to read, and something that I think I'd like to read, or a story I just need to write.
FMA, on the hand, I know people read (or so I think, at least) so I tend to curb my more self-indulgent tics when I write for that. I'm more aware of the fact that other people are going to read what I write. It changes the dynamic of writing, because I'm not completely measuring my work on my own terms, I'm also trying to judge it by someone else's as well.
So yeah, what do you guys think you are? Where do you fall on the spectrum? Does it vary? Does it not vary? What?
ETA: I want to do yuletide, and I haven't done it before. Regularly poke me into writing a New Year's Resolutions fic.