Jeremy Francis Markley was a shy nine-year-old boy who escaped his troubles by daydreaming about Spider-Man but fell to his death trying to imitate his hero. His father, a man who achieved wealth using a mutant ability of persuasion, was devastated and blamed Spider-Man. Vowing revenge, Markley became Fusion, an apparent amalgam of every hero and criminal in the city. Carrying a mannequin and a small metal mallet to Edgar Tower, Fusion used his persuasion power to convince people that his mallet was Thor's hammer, that his arm morphed into the Hulk's arm, and that his body grew Dr. Octopus' tentacles. On the roof, Fusion convinced police that the mannequin was a hostage. Fusion made Spider-Man believe he had multiple super-powers and then convinced a police pilot to crash by persuading him that his helicopter had blown up. He tossed the mannequin off the roof, letting Spider-Man know it was a bomb. When the wall-crawler webbed it, the mannequin exploded, killing three hundred people in the building.
Fusion publicly blamed Spider-Man for the deaths and challenged him to a fight at the site of Jeremy's death. There, Fusion, simulating Iron Man, Sandman, Venom and others, attacked Spider-Man. His spider-sense useless against the power of persuasion, Spider-Man thought he had been struck by a Hulk-powered punch that had broken his neck. Fusion dragged the "paralyzed" Spider-Man to his hideout where he blamed him for the Tower deaths, explaining that the bomb was built to explode only if stopped in mid-air. Spider-Man refused to accept this guilt and in his resolve discovered that his neck wasn't broken after all. Spidey's strength of will allowed him to now resist the persuasion and Fusion was forced to flee.
Fusion later turned up at BioTechnix, a company that designed prosthetic limbs containing processors that could take over the wearer's mind. Fusion apparently cowed Dr. Octopus with his powers and Ock created "lost-limb" accidents to high-ranking government personnel who were then mind-probed with BioTechnix prosthetics to locate "John Hancock," a top-secret device that traced radiation signatures, so that they could locate Spider-Man. After obtaining John Hancock, Ock, feigning submission all along, attacked and nearly beat Fusion to death. Spider-Man defeated Ock and intentionally damaged the device to discourage any tracking. Fusion faced a lengthy hospital stay and presumably a longer prison stretch for his crimes.