I'm considering a re-watch, which is a baaaad thing, because I still have to: watch Classic Who, watch the original Star Trek series and all the movies, finish watching Doogie Howser, M.D., and play Kingdom Hearts II again. Oh, and I promised a friend I would watch Castle. Oy.

I do not know those Avatar pairings, but I think I see what you mean. For me it depends on the relationship, but I tend to like the sibling kind the best. It's half the reason I started watching Supernatural, in fact.

Sorry for all the edits, I keep screwing up my HTML.