What is special about the replicant Roy Batty?

Roy Batty is a Nexus 6 Replicant. This means he is superior than the average "natural" human. Roy is superior in terms of intelligence, strength....Roy is the leader of the Nexus 6 Replicants, played by Rutger Hauer. His goal is to find Tyrell, his creator, to get reprogrammed for a longer life. Batty kills Tyrell when he finds out that this won't be possible. Roy Batty eventually saves Deckard's life before expiring in the film's final battle scene.