Originally a partner of the mind-altering assassin Black Swan, Nijo spied on Deadpool as part of the Swan's plan to exact revenge for Deadpool falsely taking credit for the Swan's assassination of the Four Winds crime family, which included Nijo's brother. Nijo was killed by the Swan after refusing to kill Deadpool's assistant, Sandi Brandenberg. Confronted by Deadpool, the Swan's powers flared out of control, telepathically linking their minds and mixing traits and abilities before the bomb detonated. Now sharing Deadpool's healing factor, Nijo was resurrected, but with no memory of his identity or past except for a burning ambition to become the world's best mercenary. He instinctively sought out Sandi, who took him in due to his resemblance to Deadpool. He named himself Alex Hayden after the composers Alexander Grieg and Josef Haydn, Sandi enlisted the help of her mercenary boyfriend Taskmaster and the gunslinger Outlaw for Hayden's training, creating within him a combination of Deadpool's and the Swan's skills.
Alex and Sandi formed the Agency X mercenary service, and were paid for their first job with a run-down amusement park. With Agency X, Alex romanced Outlaw and entered a challenge to steal the Punisher's guns. He also encountered the young mutant Mary Zero, whose power prevented everyone except Alex from noticing her existence. Alex also roughed up the creator of Internet pop-up ads, hired Arcade to upgrade the amusement park, and clashed with the Four Winds and their new leader, Higashi. In a showdown at the park, Alex and his allies battled super-criminals hired by the Four Winds. Despite overwhelming odds, Alex and the others survived and made peace with Higashi; but only after he hired Alex to eliminate his troublesome lieutenant.
Sandi briefly romanced Alex while they were on an assignment to kill retired super-hero Fight-Man. Alex was then confronted by Deadpool and the Black Swan, who proposed they restore their original selves. During the transfer, the Swan betrayed them and absorbed their powers. Aided by Taskmaster, Outlaw, and hired guns from the Four Winds, Alex and Deadpool killed the Swan after stretching his newfound powers past their limit. Reforming Agency X, the mercenaries went on vacation with the Black Swan's stuffed corpse.
Later, Alex was hired to prevent Deadpool from restoring the mind of Cable, who had become a would-be world savior. He was ultimately unsuccessful.