Mountjoy was what Bishop
referred to as a 'merger', one who had been trained by the Emplates.
By hiding inside the mutant Bantam
, Mountjoy was able to travel to the present through Fitzroy's
time portal undetected. Once in the present he remained hidden until he made an attempt on Bantam's life, as the diminutive mutant was the only one that knew he had escaped from the future. This brought him into conflict with Bishop and the X-Men.
With the help of a holographic version of Bishop's sister Shard
, Mountjoy was defeated and presumably incarcerated. He later surfaced with the London version of the Hellfire Club
, possessing the body of the mutant called Scribe
. In a battle with Madelyne Pryor
he was forcibly evicted from his host.
Mountjoy's primary mutant ability was to merge his body with that of others. He manifested this power in two ways:
He can enter a person's body, possessing them. The victim remains conscious, but Mountjoy's will is dominant (though some strong willed individuals, such as Bishop are able to fight and regain momentary control of their actions). The possessed person's, called a 'mount' or 'ride' by Mountjoy, body and clothing remain the same, but Mountjoy's facial features are usually superimposed over their own.
The second manifestation was known as a 'hostile takeover', wherein Mountjoy absorbs the person into himself. In this instance Mountjoy's body will take on some physical traits of the person, or people, he has absorbed and sometimes their faces or limbs can be seen struggling from his body. Mountjoy can absorb several people at once and has access to all of the memories and abilities of anyone he has absorbed (for example he once absorbed Gambit, Psylocke and Archangel and possessed Archangel's metal wings, Psylocke's telepathy and Gambit's kinetic charging power). Unless he is forced to divest a victim shortly after he has absorbed them they will cease to exist.
Additionally Mountjoy is able to project a 'Basilisk field' within a five foot radius which slows the reaction time of anyone within it (though there is some evidence that he needs to make eye contact for this ability to be effective). He also has a degree of enhanced strength, enough that he is able to rip off a car door and make large acrobatic leaps.
Mountjoy is an excellent hand to hand fighter, but prefers to avoid physical confrontations where possible. He uses two small knives as his weapon of choice.