The most interesting idea I've heard of the Devil, is that he is a Simian Dei. Not in the sense of being God's monkey, but aping God and his actions. Unfortunately, the Devil's sense of good is warped by his pride and therefore his inherent evil, so his actions lead to the horrors most commonly attributed to him.
In this way the Devil is in fact a well meaning child, but through his misfortune of misunderstanding the ineffable plan, mucks up the fate of the universe.