Lately, I've found myself intrigued by the mindbender prestige class in Complete Arcane. Mind control isn't a theme I've explored much, but I think I'd enjoy giving a character like this a try. The catch is, of course, that the mindbender is a pretty crappy class for a normal D&D game (and would probably annoy other players even if it wasn't), which is why I'd rather do this as a one-on-one.
I haven't given the character's personality too much thought yet, but it would probably be more interesting to play a neutral mindbender who is seduced by the exploration of his powers than a mindbender who starts off as an evil sociopath.
I'm flexible as to the exact setting, although the Forgotten Realms might be a problem, simply because even a high-level mindbender would probably get tracked down and eliminated by one of the many, many powerful characters in Faerun.
So, any takers?