Rebellion: As an adolescent 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)
While foraging or hunting for food, you have an encounter with a trapped predatory beast. Instead of slaying it, you free it. The freed beast disappears. Later, you are trapped by a falling log. The same beast reappears, aiding and freeing you.
Faction. A factional enemy could be a religous order, a merchants guild, an order of assasins, or an order of holy knights. It is a enemy that may have agents and spies taht act of their behalf. Could be on the run, part of a rival faction, or want to join