In many ways, no one understands Batman better than the Joker. They complete one another. The Dark Knight jumps all over this theory. Take these Joker quotes:
Don’t talk like one of them. You’re not! Even if you’d like to be. To them, you’re just a freak, like me!
This is what happens when an unstoppable force meets an immovable object. You truly are incorruptible, aren’t you? You won’t kill me out of some misplaced sense of self-righteousness. And I won’t kill you because you’re just too much fun. I think you and I are destined to do this forever.
Villains whose character traits thematically connect to and complement the hero’s own development can work far better than any other kind.
Acts of Evil Can Be Expressions of Love
The Joker clip above suggests that a villain may commit evil in order to attract the hero–purely because the villain wants to spend time with the hero. In this sense, each villainous act that lures the hero to the villain is more an act of love than a crime.
I’ve heard of versions of the Satan myth where Satan rebels because he refuses to serve humans out of love for God. He cannot conceive of serving anyone but God. This sounds far more intriguing to me than your typical ‘quest for power’ version of the story.
It’s All A Great Game
One of my favorite series of Looney Tunes shorts features Wile E. Coyote (or Ralph E. Wolf) fighting Sam Sheepdog for his sheep. At the beginning of each short, the Wolf and Sheepdog clock in for the day’s work and greet each other graciously. At the end of each brutal day on the job, they clock out and politely farewell one another. Their conflict is nothing personal. It’s just what they do.
The Joker seems to exist in the same world. The eternal struggle between good and evil is a misnomer to him. It’s all a Great Game–and his job is to play that game. He’s not a villain. He’s just the best player on the other team.
From this we can infer that the most intriguing (and threatening villain) is the one that views the fight between him and the hero as the way things are supposed to be . Rather than hoping to win or for the conflict to end, this kind of villain wants it to keep going on without end.
In Amadeus, though Salieri hopes to kill Mozart, I think that he really hopes that they can play his little games for all eternity.