Forerunner in a Galaxy Far Far Away

Warrior was Forerunner general during the of the Forerunner Empire, he led his forces against humans and other alien species but when the Flood came he knew that thier no stopping them, Warrior went the Librarian to about the future and she suggests the Halo rings where it would kill the flood though with a price of taking life and Warrior agrees. Warrior tries to reach the Ark to activate the rings but he was an ambush by the Flood, not wanting to be killed by them his last attempt escape was to slipspace into the unknown of space.
Centuries have passed since the Forerunner wars, warrior wakes up from his cryosleep discovers that he's not in the same galaxy expect this one is in another galaxy that's far far away.....