Never thought of a prisoner/guard idea, sounds interesting going to try it.
I really like using the bodyguard roleplay...its so many different things you can do
Push/pull: "I'll pay you 1,000 dol...matter fact I'll pay you 1 french frie a day."
Story: Talk about an incident where she had to protect your or anything that still plays the dynamic of Bodyguard.
Cold Read: "I can see it now, your all quiet and innocent but deep down your a bad girl...I'm kind of liking that it makes you seem tough...you know what your my new bodyguard!"
Kino: "In order to be my bodyguard you must pass my Strength test...first you must beat me in arm wrestling...then lets check out how tough you really are, flex a muscle."
C&F: "Now when we go to clubs you must protect me from all the women trying to grab my sexy body and don't betray me by helpping them and jumpping on me."
Ok you get the idea.
Some other roleplays that I do are:
Runnaway lovers (You both ran from home and met each other and now together)
Bonnie/clyde
Marraige
Bf/GF
Gang (Your the leader and she has to join)
Sexual innuendo: "To join my gang you have to get fuked in...we shall see if you can hang on for atleast 1 minute...actually no I don't think you can handle getting beat up for 1 minute." (I'm thinking bout field testing this)
I must say Roleplaying is one of the most fun techniques to play around with. So many different things you can do while keeping that roleplaying frame. It's also good call back humor.