It's odd, but I've heard people say that how you RP and how your characters behave - particularly with other people's characters - is an indication of the inner workings of your mind; and how well you get along with people.
Hmmm... Michael and I...
have 1 pair of characters who started out with mine trying to kill both his char and herself, now they seem to be friends. Tentative friends, but still.
1 pair (technically, I'm not certain they count, as they're from different universes alltogether) that hate each other, his tries to terrorize mine.
2 pairs who are quite in love. One pair is hormonal (somewhat disturbing when you take into account that at some point, we've both said our half of that pair is the character most like ourselves) to an almost amusing extent, the other pair is very sweet.