Character profiles are optional for this one!  My personal preference is to figure out my characters as the story progresses.

Magic would be ok.  It could easily be why your character was imprisoned in the first place.  (That's sort of what I'm assuming about Gisk's hedge wizard, but he hasn't revealed anything specific yet about why Rolf was thrown in prison.)  If you go with a character with magic, just keep it relatively low powered.  

Hmmm....  I can't think of anything else restriction-wise.  (Well...  unless maybe to say please no demons, demi-gods, or the like!)