Well, this is more of a unoriginal desire list. Until I can think of some good games and plots, I'll just toss a few idea's that I think would be fun. (Keep in mind, I only play the male roles.)
(Taken) WoW - I like WoW...My ideal play would be something along the lines of a Draenei or Night Elf female being taken by one of the horde...Tauren, Blood Elf, Orc, Troll....Could even go as Undead....But I don't much like Undead....Hell, I could even play a beast, mob, or boss from the game too. (Most anyway. And partial to the Draenei)
Final Fantasy - I like Yuna. Her innocence appeals to me...Something I'd be able to corrupt. Be it beast, bad guy, or one of her friends. Aries and Tiffa are also favorites of mine. As far as settings go, I'd be willing to try a lot of things with them.
(Taken) Demon - I could see myself playing a demon, be it summoned from hell by a rich, stuck up girl that has no idea what she's doing...Or in a more fantasy type setting where it takes a Drow woman and kidnaps her, using her for hisown personal toy that he can mold to his perfect toy.
(Taken) Dreams are Alive. - Well, this is a actual game that I used to RP with someone on AOL. The way it went, the woman was pure, virgin, about twenty years old. She'd never had sex, nor seen a man nude in person before. Never even had an orgasm before. (These details aren't important and can be changed.) Never the less, a spirit comes to haunt her at night, as every time to falls asleep she is subjected to the sexual exploits of the spirit. This game can involve anything in the site rules, as even if she gets killed, it's only a dream, so she'll be perfectly fine when she wakes, as well as the next time they play. Limits will have to be set up beforehand in detail, as there would be a strong possibility for many things to happen. Sometimes, it could be gentle teasing, and soft lovemaking. Another, he could have her thrust against a wall and using her without her will. It all depends on how things work.