I think most if not all of the standard origins careers could accommodate a social outcast background. I'll use OLD as my example but this could probably also apply to the other genre systems. Like so:
Acolyte, Page, Wizard's Apprentice: you ran away from home to become a....
Farmer, Primitive, Slave, Urchin: you/your family was driven out of their rightful place and forced to live as a...
Noble: your family did something treasonous in the recent past (example: fought on the losing side of a civil war). Maybe your family's political power prevented the king from outright killing you all, or maybe you flipped sides at the end of the war, or maybe he/she issued a general pardon as part of the end of the war, but whatever the reason you aren't dead, the nobles (and commoners) from the 'loyal' faction remember your original treason and treat you like dirt. Another possibility: your family isn't noble by birth. You did something underhanded for the king (or maybe some other country's king) and were rewarded with a title, but everyone from your original community thinks of you as a sellout while the more traditional noble families think of you as a lowlife social climber.
Then for mechanics, you make this your hook. That way your dice pool explodes any time your outcastiness would give you some sort of edge.
