Superwholock :D This is how the Christmas episode is going to happen, Dean is going to kill the doctor and then he's going to regenerate and send dean to hell.
I never understood why people always portray Death as evil. As this post said, he is the definition of neutrality. If you believe in some sort of heaven or hell, he's the middle, he doesn't have a side. He either does stuff (theoretically) for his job or for his benefit. He doesn't "take sides" so he's not a threat.