Chapotraphouse

How Dondarrion describes it is that he isn't alive. That his soul was basically grabbed as it was fleeting away and bound back to the necromantically animated body. Considering that Red Priests are shadow binders, this makes sense that they can bind souls. The body itself should have ceased functioning, it had huge open wounds and missing chunks of organs. He smelled badly. He was basically a zombie that had someone in the driver's seat. Every time he got "resurrected" he came back with less and less of himself, more and more an unthinking zombie. That's why he passed off the baton to Lady Stoneheart, he knew his next resurrection would be impossible or completely out of control.