I know, the whole sibling/betrothed thing is a little gross but somehow I think that the series will end pretty tragically and no one will actually get together. So at least we won't have to think about the incest babies...
I like YuukixZero; I still think that the whole thing with Zero and Yuki isn't finished even though he's so angry about her turning into a vampire. I just don't think Zero can hate Yuuki, and even if he tries attacking her they both still care about each other. Not that Kaname would let it get that far. Of course considering the fact that Zero will eventually go crazy I somehow don't think that it will work out in the long run.
Of course my favorite part is them rivaling over Yuuki and her having to pick, and I don't think that's over yet.