A student at Xavier's School for Gifted Youngsters, John became best friends with Bobby Drake, who ironically ended up having the complete opposite powers. When William Stryker attacked the X-Mansion, John escaped with Bobby, Rogue and the Wolverine. It was this that allowed him to get into contact with Magneto and spur up his geneticist tendencies. Fascinated by Magneto's ideals, John joined the Brotherhood of Mutants and took the codename Pyro. He violently fought against the Leech Cure culminating in a fight with Bobby during the Battle of Alcatraz. After losing this fight, Pyro was incarcerated by the authorities.
John possessed a degree of control over fire, meaning his X-Gene made him a Pyrokinetic. However, he was unable to generate any fire himself. Rather, he was forced to manipulate pre-existing fire. Due to this limitation he had to wear flamethrowers on his hands.