No Hope of Redemption

They save them, they kill them, they become them. And they are still them, and they are still them. It's not reincarnation, it's a cycle, an unbreakable cycle... It's also interspersed with a second cycle and stories that the protagonist didn't see in the three cycles. He knew that he was in a cycle, but he did not break it, but waited for the next cycle to begin... For eternity...