jdrakeh
Front Range Warlock
I played in a campaign where one of our players got tired of his character, so working with the DM, they arranged to have that character betray the party and disappear into the night (literally; they sabotaged the party's air ship in the middle of the night and escaped undetected). Later, that character returned as a villainous NPC, having mutated into a gross human/dragon hybrid. He blamed the party for his woes, so sought to exterminate them. It was a GREAT campaign arc and we all had a lot of fun with it.