There's a lot of good Twilight UC fic at
this lj community. It's been so long since I've read Twilight fic that I can't think of any Carlise/Rosalie to rec. Most of what I've read of them is dirty though, anyway, so I wouldn't feel comfortable reccing those anyway.
Oh, there was also a
Twilight Uncanon Drabble-A-Thon if that interests anyone looking for fic.
ETA: I do really want to recommend this Edward/Tanya fic though:
Memento Mori: remember your mortality - 10 things you didn't know about Tanya (and Edward)
I simply love that fic.
