Mister One and Mister Two were Shi'ar Empire Subguardians, prototypes of the technology that would be refined into Warstar. Through unknown means, they found themselves stranded on Earth.^[1]

They were found on the side of a highway by a man named Joe Keegan, who brought them to his home. Assuming they were mutants, he placed an advertisement in the local newspaper asking for assistance from any individual or organisation equipped to help them. The advertisement was read by both Captain America and Magneto.

Captain America took Mister One and Two to a SHIELD facility for study, while Magneto began planning to capture them for his own ends – having recently come into possession of a tiny spaceship, he hoped to recruit Mister One into his new Brotherhood and then take advantage of his tiny size to explore the interior of the spaceship.

Magneto's Brotherhood attacked Mister Two, creating a diversion while Magneto himself abducted Mister One. While being held captive, Mister One was able to communicate his location to Mister Two, allowing Captain America and Two to confront Magneto and the Brotherhood. In the ensuing battle, Burner used his full power against Number Two, killing him. Feeling the death of his other self, Number One crawled inside the tiny spaceship, activating its self destruct as a final act of revenge against Magneto and his Brotherhood.^[2]

Both Number One and Number Two transmitted data on their deaths back to the Shi'ar as they died.^[1]

Mister One and Mister Two existed symbiotically, one mind in two bodies. The tiny Mister One was a powerful telepath, while Mister Two had superhuman strength.

Mister One was immobile and mute, and Mister Two had no mind of his own. As such, each was entirely dependent on the other.