Biography page 1
The man now known as Proctor hails from Earth-374, elsewhere in the multiverse. On his world, he began as a hero, the extra-dimensional counterpart of Dane Whitman, the Black Knight. Proctor led the Avengers of his reality, including familiar faces such as Captain America, Iron Man, Black Widow and Crystal. None caught his attention so much as when Lady Sersi of the Eternals visited them in New Amsterdam. Seeking adventure among mortals, Sersi joined Proctor and his 
Avengers, and the two of them became lovers. Proctor fell madly in love with Sersi, and for a time she returned his affections. The two Avengers were married, and Sersi made Proctor her Gann Josin, a unique and intimate form of mental bonding by Eternals where partners shared each other's thought patterns, as soul mates.
However (according to Proctor, at least), Sersi proved fickle and eventually lost interest in him. Proctor was emotionally broken by his wife abandoning him, made even worse by the fact that they still shared a psychic link. What happened after that is unclear, but Proctor apparently gave in to the blood curse of the Ebony Blade, the enchanted sword he wielded. The blood curse and Gann Josin bond interacted in an unexpected way, causing Proctor to change and develop many abilities traditionally found in the Eternals. Seeking revenge on Sersi for spurning him, Proctor began to subtly influence her through their Gann Josin bond. Proctor caused Sersi to slowly go insane, simulating the effects of a documented Eternal illness known as the Mahd W'yry. Eventually, Sersi turned against her fellow Avengers and Eternals and apparently brought about the destruction of their entire Earth. Once the devastation was irreversible, Proctor stepped in and killed his wife with the Ebony Blade, completing his revenge. Or so Proctor tells us.
After escaping the destruction of his reality, the madman's monomaniacal obsession with Sersi led him to repeat this revenge fantasy on numerous worlds. Proctor somehow seized power over Ute the Watcher, holding the barely alive entity in stasis to preserve his life. Proctor claimed Ute was reduced to the Watcher equivalent of brain death by Sersi's cataclysm but, given his mania and pathological lies, Proctor contributing to Ute's injuries is almost a given. Through access to the Watcher, Proctor gleaned knowledge of the multiverse, and sought out other Sersis to torment. The power of the Gann Josin bond carried over to other versions of his wife, allowing Proctor to influence their minds without them even being aware they shared a bond with this interloper. Slowly inducing instability in each Sersi he found, Proctor drove them to madness and made each Sersi responsible for hurting her loved ones before destroying the world itself.
Proctor's revenge fantasy evolved over time, becoming more elaborate as he enjoyed adding new wrinkles to his twisted scenario. Oft times, Sersi was an Avenger and the genesis of her breakdowns began with an attack on her teammates. Like a serial killer collecting trophies, Proctor would occasionally save an Avenger from Sersi's mad attacks. He wove a story of how Sersi's madness was consuming the multiverse, gathering these Avenger refugees together as a team of agents for his amusement. These Gatherers allowed Proctor to play the earnest 
harbinger, prophesizing Sersi's downfall and offering these fallen heroes a sliver of hope towards gaining revenge and stopping the next cataclysm. He cast his Gatherers as brutal but heroic figures trying to stop Sersi before she went mad. The Avengers would naturally fight these Gatherers in order to protect their friend, only making it even more delicious to Proctor when his work through the Gann Josin caused each Sersi to turn against her protective teammates anyway.
The Gatherers were largely in the dark about Proctor's true nature. Using the powers he developed over time, Proctor deliberately manipulated his Gatherers' brain chemistry to keep them disoriented and loyal to his goals. Proctor's psychic influence was combined with his natural charisma and purported knowledge and experience on the issue to keep the Gatherers from plainly and coherently conveying the nature of their mission to the Avengers when they met. The Gatherers were also somewhat off-balance due to the nature of their dimensional transit. Like matter and anti-matter, a Gatherer could not exist on another Earth for long if their doppelganger 
from that Earth still lived. Their counterpart must be "gathered onto them," as Proctor put it, a process where the Gatherer was stabilized by psychic assimilation of their twin. The template would die, but the Gatherer would be spared crippling insanity. It was necessary, as Proctor said. But then, Proctor lied constantly.
Countless Earths and hundreds of Sersis later, Proctor claimed to have spent centuries on his mad quest. Gatherers came and went, sacrificed to his plans when convenient and replaced by novel new recruits when it amused him. In the current era, his active Gatherers included Magdalene, Sloth and Mother Cassandra, the oldest of the Gatherers and perhaps closer to the truth than the others. Magdalene had been Proctor's lover when he first rescued her, a dalliance that amused him for a time, but she could find no love in his obsessions, and they drifted apart. In time, Proctor identified Earth-616 as the Prime Earth from which all other Earths were derived. Through Ute's knowledge, Proctor believed eliminating the Prime Sersi would cause a chain reaction, wiping out all remaining Sersis in the multiverse.
By this time, the Gatherers were conditioned to see local Avengers as their enemies, fools in the making who would never accept the truth about Sersi. Before beginning their campaign against the Avengers of Earth-616, Proctor gathered the Swordsman from a fallen reality, Philip Jarvert. The Swordsman of Earth-616 had died years earlier, and so this Swordsman never went through 
a proper gathering. Proctor chose to take advantage of Swordsman's instability, keeping his brain chemistry off-balance and leaving him deliberately fuzzy about alternate realities and the difference between his world and the current one. Swordsman believed he had been left to die by the Avengers of his home reality, a need for vengeance that he transferred onto the Avengers of Earth-616 (with Proctor's help). Proctor did not plan for the romance that developed between Swordsman and Magdalene, though. Neither Gatherer fully understood how dangerous Proctor became when he felt scorned.
At Proctor's urging, Swordsman and Magdalene struck out at the Avengers. Using their multi-dimensional knowledge of Avengers security codes, the Gatherers found it easy to infiltrate Avengers Mansion and plant a false alert from the Fantastic Four. A team including Proctor's counterpart Black Knight, Crystal, Vision and the new Thor responded to the distress call and were struck down by Swordsman's power sword. The Swordsman's confusing but passionate accusations threw the Avengers for a loop, and bio-metric readings made during the battle 
confirmed for their computers later that this Swordsman matched the man in their history tapes. Without a gathering, though, Swordsman was prone to migraines in this new reality, and Magdalene was forced to flee with him back to Proctor before doing any serious harm to the Avengers. In truth, Proctor only wanted them disturbed... primed for future surprises as his scenario played out. [Avengers (1st series) #344]