Vexen is sort of alive, but Weird. He's a soul with only a tiny fragment of a heart, piloting the magical equivalent of a fossil of a body that's already faded away. According to the laws of his universe, he's a being that should not exist, yet does anyway because his soul was too powerful to fade with his body when he lost his heart. He was originally human, but probably doesn't quite read as such anymore.

Magically speaking, he is a quite powerful mage (on a scale of 1-10, his raw magical power canonically ranks 8).