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.
Political. A politcial enemy might inlcude a local magistrate, a noble who rules the region, or a monarch ruling the kingdom. the NPC might have offended a local ruler,become an outlaw, or a be a political rival.