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.
Social. A social enemy might be a personal rival, an idealogy, or a cultural trait. Its an enemy tied to interactions with others, they may have trouble fitting in, be a social outcast, not identify with their culture, or be wanted but their own kind.