I think Ras actually gave up. Not that he fought back. He's a machine. He has no light to offer and so is of no value to the darkness. The problem is they built him to survive. One command over road another. He is probably sitting next to the darkness right now. Un effected by it. In order to survive he had to take the world literally off its shoulders and in doing so watched it turn to ash. But he survived. As programmed.