Red John
Over the years he'd grown accustomed to the thrill of blood, the flash of fear in his victims' eyes always made his heart beat faster.
However, even murder was slowly but surely losing its allure; the only thing that really mattered to him now was the glorious rivalry he shared with Patrick Jane. Red John both loved and hated the man, just as much as he loved and hated himself.
That was the single reason why he kept on killing; Patrick's approval was like the air that he breathed, he couldn't disappoint his best enemy even if he wanted to.