Jamie’s power is the ability to create duplicates of himself at will through an unknown process whenever he is struck, or even when he snaps his fingers or stamps his foot. Each of the duplicates is completley capable of independent thought and can create duplicates of himself. The original Madrox is telepathically and emphathically linked to his duplicates, and can absorb them back into himself at will. When Jamie was born, the doctor’s slap caused him to multiply into two identical babies, which was rather a surprise to his parents and the doctor. Professor Charles Xavier suggested that the Madroxes move to Kansas and raise the boy in privacy. His father created a suit for him to wear which would absorb kinetic energy, the presumed source of the duplication. When Jamie was 15, his parents were killed by a tornado, and for the next few years he ran the farm by himself until his suit one day malfunctioned. He ran for help to New York City, where he met Mister Fantastic of the Fantastic Four. Mister Fantastic helped him with the suit and informed Professor Xavier of the dilemma.
Jamie was invited to join the X Men, but he declined. Instead, he moved to Muir Island to assist Dr. Moira MacTaggert with her research. There he met Theresa Cassidy (Siryn), the daughter of Sean Cassidy (Banshee). Syrin eventually joined X Force and Jamie returned to Muir Island. He ended up being associated with the original X Factor when the group was under Val Cooper's control. His chief contribution to the group was to make Val mad. He became a close friend of Wolfsbane, a future member of X-Factor II.
Eventually, the original X Factor was disbanded, and Val Cooper founded a new team, creatively named X Factor II, whose goal was to create a more positive image of mutants in the public eye. With the help of Professor Xavier, Cooper persuaded the X-Men veteran Alexander Summers (Havok), brother of Scott Summers (Cyclops, the X-Men’s longtime leader), to join the team. The other members included Havok’s girlfriend, Lorna Dane (Polaris), the former New Mutant Rahne Sinclair (Wolfsbane), Guido Carosella (Strong Guy), a former bodyguard of the mutant rock star Lila Cheney, and Madrox himself.