Rezyl quickly became a leader among the survivors of the Collapse who came seeking shelter under the Traveler, guiding humanity through infighting as well as against alien scavengers to create the City — and its walls.1
Despite the successes of the City and its Guardians, Rezyl grew frustrated at the constant battles. He is described as "growing tired of small wins, however meaningful".2
Rezyl traveled to the Moon where he discovered that the Hive were still active. He proceeded into the Hellmouth without his Ghost and encountered Xyor. After battling many Hive, Rezyl faced a knight covered in bone armor.3
After two days Rezyl emerged from the Hellmouth, bearing the bones of the knight as a trophy. While contemplating the reappearance of the Hive, Rezyl grafted the bones onto his hand cannon, Rose.
The next steps of Rezyl Azzir are not clear, but the events on the Moon and the fact that Rezyl's hand cannon was named Rose suggest that he abandoned his existing identity and created a new one, Dredgen Yor.