CORNBRINGER
I in my opinion of the LoK series where they introduce the First Avatar Wan, thought the way Wan handled thing around him is rather selfish. Both of battling spirit give warning to him to go away and in his own self-justification separate both entity. That recklessness set things go awry all the way. Just a moment after separation Vaatu incites more spirits to go rogue and forced human to defend themselves and get more creative with their bending. But then if he didn't start it human will go on forever living on the turtles back. Or they just get off the turtle when they are more ready or smarter. It just that, Avatars preach about balance but they are a living proof about forced balance. Vaatu is just the poison the world need to get a bit drunk.