You and another player character (or a notable or popular NPC in the GM's campaign) become acquainted with each other. Select an appropriate character (work with your DM to determine details)
Poverty You or your family fell on hard times and were unable to pay taxes, resulting in either your character or a family member spending time in prison. Work with your DM to detirmine the details)
As an adult you joined a rebellion against the local ruler, if successful you are outlawed, if it failed you escape, with only friends and family knowing your involvement. (Work with your DM to detirmine the details)