Millions Knives

Knives is Vash's twin brother. He is the opposite of Vash. Basically his main goal in life is to make Vash's life a living hell, why? I think it's because Vash loves the humans, and Knives hates them. Their opinions vary greatly, and because of this, the two don't like each other very much for the entire show. It isn't until the end when Vash fights Knives that we discover, for all his big talk, Knives is a big baby. He hates pain, and is defeated because of this weakness.
Knives's look on life is a very realistic one, if not cynical at times. He believes that you never have a choice in a situation. You look at it and take the route that will ensure your survival, and oftentimes, the other's death. This differs greatly from Vash's belief that there are always other options. (I agree with you Vash!:)-) If you go along with the typical good vs. evil story, Knives had already lost from the beginning, because of his fixed views.