He's shown to be depressed and doesnt give much care to the world and not really evil as most would think as being the fusion of a negative energy and destroyer of worlds. He takes more of Error's personality rather than of Nightmare's. After his corruption, he's shown to be sly, snobbish, unsettlingly calm, classy in personality not in fashion sense, ambitious, charming and arrogant. He likes dominating things and making them destroy each other for his own amusement. He's well-mannered.