The home town where the character lives is destroyed, there is little loss of life. However, after the disaster passes, the area is rebuilt and becomes more prosperous than ever before. (work with your DM to determine details)
Divorce: During your adolescence your parents split up and you were forced to chose which parent to live with (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.
Monster. A monsterous enemy could be something as weak as a goblin to as powerful as a ancient dragon. They consist of monsterous races and creatures. They might have done battle with the creature, been robbed by it, wanting revenge, or hunting it.