Given that I'm a big The Lord of the Rings fan, I think it would be fun to try combining that setting with my roleplaying interests. The role would generally go as follows:
I'm a human serving Saruman a couple decades before the War of the Ring. I'm truly convinced that he has the world's best interests at heart and am doing everything I can to support him in his attempts at conquest. As I have some aptitude for magics, I am working on a very important problem: the pacification of Saruman's clashing and unruly army. In short, my theory is that a race of sex slaves could be bred which would serve his troop in large numbers, keeping them occupied when they aren't doing his bidding. As a member of the second generation of this slave race, you stood from the others on the basis of certain qualities you possessed.
I won't set in stone what race(s) you've been bred from, nor what happens in the story, except to say that I do not enjoy struggling with a submissive character constantly. In this role, particularly, it would be silly to do so, as the female character (to say nothing of the male) would be fairly expendable and wouldn't last long if she caused trouble.
If you're a creative female roleplayer who knows a bit about The Lord of the Rings, pm me or post and let me know you're interested.