It’s not uncommon to meet people who say they love PvP. I don’t think I’ve seen them making characters who are in opposition to their PvP loving friends’ characters so they can play that out, but I would presume that it happens on games that are more PvP-friendly than ones I’ve been playing.
Yeah. Most of the games I’ve seen that have been CvC friendly and succeed at it have built up a lot of OOC tools and methods to make that work. I have yet to see the OOC techniques and tools for that really catch on in the MU hobby, but I have seen it work in other online RP formats and in live play (the strongest examples of this were LARPs where workshops and care were given to make sure the players understand that their characters are in conflict where as the players are not).