snupin and severus/regulus are my faves as well. I've written a couple of implied sev/reg fics and one where they kiss, but that's it. I enjoy reading good snupin immensely, but I don't write it, as I fear I wouldn't be able to pull it off.

I prefer my own personal Lily too ;-), though when writing them as teens I will sometimes keep it slightly canon, but flesh out her character more, and try to figure out her motivations and stuff. Stuff that Rowling just failed to give us (whether do to lack of time, space or interest I just don't know).