I think Draco is said to dislike Lupin in PoA, though I can't remember if there's any given reason aside from an ornery insistence on hating anyone Harry likes.

He (Lupin) dresses badly, also. (Rather confirming all the speculation over Draco's sexuality, there.)

It seems that it would be so much more interesting to make it messed up. Power play. Revenge fantasies.

Helenish has done a short series based around this.

Another one where I'm not quite clear on whether they've actually had any canonical interaction.

CoS, briefly. A quick search helper is either www.geocities.com/willowsevern or marysia.com/hpcanon

Otto Octavius/Peter Parker

Is there a lot of Doc Ock fic around? I'm not really a Spiderman fan, but... *curiousity is aroused*