When I think of Joe, I think of this quote from an graphic novelist:
"When you write an antagonist, you always write him, in his mind, as the protagonist. That means, every villain of a story, to be a good villain, must believe himself to be the hero. Not the villain at all."
This is Joe in a nutshell. And in a way, it is a necessary way for the writers to write him in order to keep people watching. It is unsustainable to have your central character be 100% villainous. Joe wouldn't have lasted one season let alone three is they didn't tap into some method to make Joe palatable. B