He was a small-time hoodlum, reborn once and for all. He has undergone a huge change, and with his change comes an unexpected end. He lost his family in the apocalypse, whether it was fate or God...
He is the king of the vampires and the chief culprit of this apocalypse, because he caused this disaster. That's why. The two of them came together. He originally disdained walking with humans, but he didn't know when he fell in love with the humans he had always disdained...