History
This version of Giant-Man's past is most likely the same as that of his Earth-689 counterpart, up until after he had followed through with Scarlet Centurion's plan.
This Giant-Man, along with his fellow Avengers members, was duped by the Scarlet Centurion, into defeating and imprisoning all the other heroes and villains on their earth. Once the Avengers had completed their objective, the Hulk eventually turned on them. He was promptly defeated by the Avengers and added to the Centurion's collection. With no purpose, the remaining Avengers retired, and Centurion seized the opportunity to conquer the world, so the Avengers reunited and defeated him. Once he was beaten, they went back into retirement.[1]