Born into a future where people were dehumanized and fearful of a cannibalistic race of vampire-like beings known as the Emplates. Mentored and trained by these predators, Mountjoy created a horrific reputation that made him public enemy number one among this future's protectors.
Escape from Tomorrow
Mountjoy hails from the same dystopian future (Earth-1191) as X-Men member Lucas Bishop. The murderous Mountjoy was trained by the vampiric, mutant-bone-marrow-consuming Emplates and was considered a danger to both mutants and humans. He topped the most wanted list of the mutant-policing Xavier's Security Enforcers (XSE), but remained elusive until finally located and captured by XSE members including Bishop's sister, Shard, then incarcerated. Apparently freed during a mass breakout, Mountjoy secretly merged with mutant biotemporal displacement anchor Bantam and escaped through a portal created by teleporter Trevor Fitzroy to modern-day Earth-616 alongside a mutant outlaw army; Mountjoy separated from Bantam upon arrival.
To Conceal a Secret
After Fitzroy and all the mutant outlaws (except for Bantam) were killed through unrelated events, Mountjoy hunted Bantam for months, wanting to slay the only being aware of his presence on Earth-616. While trying to merge with Bantam, Mountjoy was attacked by a street gang, which allowed Bantam to escape to seek help from Bishop, now a member of Reality-616's heroic X-Men. Mountjoy killed the all the gang members before following Bantam to Bishop, who was in New York City for an evening. After merging with X-Man Storm (Ororo Munroe), Mountjoy battled Bishop, but when Bishop threatened to kill Storm to stop him, Mountjoy abandoned her and fled. After Bishop tracked Mountjoy to a Manhattan police precinct, the two began an extended running battle that resulted in Mountjoy absorbing many victims and murdering a police officer. While Bishop was staggered during the fight, Mountjoy merged with him and used him to access the X-Men's Westchester County mansion, intending to kill them to hide his existence. Despite Bishop's resistance, Mountjoy attacked and merged with X-Men Gambit (Remy LeBeau), Psylocke (Elizabeth Braddock) and Archangel (Warren Worthington). Bishop and a holographic matrix of Shard ultimately forced Mountjoy to divest the X-Men, and despite being tempted, Bishop refused to execute him per XSE protocol, instead turning him over to authorities.
The Inner Circle Invaded
After escaping, Mountjoy infiltrated the Inner Circle of London's branch of the Hellfire Club, perennial enemies of the X-Men and a group dedicated to power acquisition, by taking over their Red Rook Scribe (Jane Hampshire). Trough them, Mountjoy intended to gather enough power to turn entire countries into feeding pens of "human cattle." When the London Inner Circle's activities became more aggressive, a threatened Shinobi Shaw, who was now the leader of the American Club's Inner Circle, notified super-team Excalibur of Mountjoy's infiltration. Former Excalibur and Hellfire Club member Captain Britain (Brian Braddock) claimed a circle seat to discern who Mountjoy possessed. Apparently to stop rival Circle member Emma Steed and others plans to gain ultimate power from a demon beneath London, Mountjoy (as Scribe) told the Captain of the Circle's plans, and he in turn informed Excalibur. During the resulting battle, Mountjoy revealed his identity and attacked the Captain pursued and captured him; Mountjoy was again incarcerated. Later, while reforming the American Inner Circle, Sebastian Shaw bailed Scribe and (and Mountjoy) out of jail and pitted her against Circle candidate Madelyne Pryor (secretly Reality-9575's Jean Grey) to test her worthiness. During the battle, "Pryor" reached into Scribe and tore Mountjoy out of her, a seemingly impossible feat that caused Mountjoy intense agony. Mountjoy's fate following the insane Scarlet Witch (Wanda Maximoff) stripping the majority of mutant-kind of their abilities on "House of M|M-Day" is unrevealed.