Once a close and dear friend to God, the Devil was exiled from heaven after belittling God’s most prized creation–the human. Now the Devil fancies himself a rival to God. He spends his immortal life doing everything he can to corrupt and diminish God’s favorite little pet. He does not act forcefully or fright his victims into joining his side. On the contrary he is quite courteous and pleasant to his targets. This makes his revenge even sweeter when he is able to turn humans against God.
He toys with his rival by stealing the souls of humans–though what he does with them can only be speculated. Eat them? Or perhaps use their energy to create his own creations, demons? Or maybe he just enjoys collecting them? He won’t tell.
The devil is the ultimate mischievous trickster. Every move he makes is well calculated. He is sneaky, clever, and witty. Life is a game to him. The rules are constantly changing with every new discovery made and in order to pack the biggest punch against God. Though he may not play fair, he has his own moral code. For example, he only steals the souls of humans willing to give them up. He will never do anything by force, ever. To him, it just defeats the whole purpose of the game.
He is also very even-tempered, oddly enough. Even when cursed or threatened he only seems to grin.
It is only when humans are rude enough to call him by name (Satan) that he ever shows his fury.

I think I explained my interest in this character quite enough in the post on Samu and the Phoenix.