The host who carries the Dax symbiont two centuries after the Defiant crashes on the planet in Children of Time.
Yedrin Dax is a descendant of the Defiant's stranded crew who became host to the Dax symbiont after Jadzia, in the timeline the crew discovers in Children of Time. As a result he carries memories of the crash and of the founding of the colony two centuries before.
Yedrin offers the crew a way to save both the colony and themselves by duplicating the ship, but the plan is a trick to ensure they crash again so that his people will exist. The crew chooses to repeat history, only for Odo's older self to alter the course and erase the colony.