And in RoTJ, the novel: "There is still good in him." he declared. Ben shook his head remorsefully. "I also thought he could be turned back to the good side. It couldn't be done. He is more machine, now, than man - twisted, and evil." Luke sensed the underlying meaning in Kenobi's statement. He heard the words as a command. He shook his head back at the vision. "I can't kill my own father." "You should not think of that machine as your father." It was the teacher speaking again. "When I saw what had become of him, I tried to dissuade him, to draw him back from the dark side. We fought ... your father fell into a molten pit. When your father clawed his way out of that fiery pool, the change had been burned into him forever - he was Darth Vader, without a trace of Anakin Skywalker. Irredeemably dark. Scarred. Kept alive only by machinery and his own black will ..."