Courage has an opposite stat, menace. If entity A has more courage than entity B has menace, A won’t be afraid of B (per definition). In all cases, though, there’s a “threat ratio”, which is basically
menace / courage which is used to determine the range at which an entity will start avoiding the other one.
That means that, if you have an entity with 1 menace, it won’t create much fear, nor will it be avoided largely. However, an entity with a hundred will probably be feared by everyone and entities will keep a large distance away.