 Cain and Ra's al Ghul did not know that the boy still lived, and Cain began a new experiment, raising his own daughter, Cassandra, to replace his earlier failures.Ra's al Ghul's daughter Nyssa Raatko did know that "the Mad Dog" had survived.Years later, after Ra's' death, she sought out The Mad Dog and made him a member of her new League of Assassins.