David Charles Haller was born in Haifa, Israel. His mother, Gabrielle Haller, was a mental patient at a hospital in the city, her mind having retreated into a catatonic state after the deaths of her family in the war. She recovered from her dissociated state thanks to the efforts of Charles Xavier, who secretly used his telepathic powers to reach her inner self in a way no other psychologist could. The love affair between them that followed was medically unethical and ill-advised, and their relationship ended before Gabrielle learned she was pregnant with Charles’ child. Gabrielle ultimately chose to keep the boy’s existence a secret from Charles, in part because, after learning of Xavier’s psychic powers, she didn’t trust whether her feelings for him were really her own. Instead, she raised David with the help of his godfather, Daniel Shomron, who had served as her attending psychologist in Haifa.

Gabrielle later entered the Israeli diplomatic service and she and David traveled the world for a time. When David was ten, they were living in Paris, France as part of the Israeli embassy staff. At that time, they were attacked by a Palestinian terrorist cell. The attackers swept the room with gunfire, killing Daniel Shomron as he shielded David. David was terrified and the intensity of the situation unlocked his mental powers. David killed the terrorists in a wave of psionic energy, wiping their minds clean. David’s emerging powers also absorbed the psyche of the lead Palestinian, Jemail Karami, pulling the gunman into his mind.

The collective trauma of the ordeal was too much for David to cope with, and his mind shattered. He retreated from the physical world, entering a catatonic state that gave no response to his surroundings. Inside his mind was a battlefield, broken up into countless splinter personalities that ran amok through his mindscape for the next nine years. Each personality represented not only a different aspect of David’s psyche, but also a different aspect of his mutant powers. Jemail Karami found himself in control of David’s telepathic ability. Although initially furious and vengeful over what had been done to him, Karami used his newfound telepathy to read David’s mind from the inside and realized the innocence of the mind he now inhabited. He then read the minds of Gabrielle Haller and others in David’s life, and developed an empathy that he had lacked in his prior life. Jemail resolved to undo the damage that David’s mind had suffered due to his attack. Thanks to David’s telepathic power, Jemail possessed considerable control over the landscape and physical laws of the mental world he now inhabited and used these gifts to begin rounding up the splinter personalities within David. He created an ebony dome at the center of David’s mindscape as his staging ground and congregated the aspects of David’s mind he captured there, working to reintegrate them into the whole.

Over the following years, Jemail Karami was quite successful in restoring David’s splinter personalities to the core consciousness, but two personalities proved to be particularly troublesome. One was a nihilistic firebug named Cyndi, a thoroughly unpleasant and uncooperative individual who commanded David’s pyrotic powers. The real threat, however, was Jack Wayne: David’s telekinetic persona. Jack was a devil-may-care adventurer, with little regard for anyone but himself. Wayne and Karami waged a continuing war campaign against each other for nearly half of David’s life. Things became deadly serious when David began manifesting his mutant powers in the waking world. Although still catatonic, he began having fits of telepathic, telekinetic or pyrotic output that couldn’t be controlled. [New Mutants (1st series) #26-28]

No longer able to cope with her son’s troubles on her own, Gabrielle Haller reached out to the geneticist Moira MacTaggert for assistance. Having risen in the political world to become Israel’s ambassador to Great Britain, Haller could easily beg an audience with MacTaggert, but was unable to keep the identity of David’s father a secret when Moira insisted Charles Xavier would be better suited to help the boy than she. [New Mutants (1st series) #1] David was brought to the Muir Island Research Center for care but Moira was unable to breach his catatonia and connect with the boy underneath. She finally convinced Gabrielle Haller that there was no hope for David but to alert Charles to the situation. [New Mutants (1st series) #25]

As the war for David’s mind escalated, he began to absorb the psyches of those nearby as he had with Karami, beginning with Muir staff Tom Corsi and Sharon Friedlander. Xavier and his New Mutants arrived on Muir Island at Moira’s request, but Charles remained unaware of David’s true relationship to him. He attempted to telepathically penetrate David’s mental barriers, but was forcibly expelled from the psi-scape. One by one, David abducted the minds of Moira, his parents and the New Mutants, bringing them inside his subconscious to a bizarre mishmash of Paris and Beirut. Inside, Xavier and the New Mutants encountered Jack Wayne, who convinced them he was on their side. Jack claimed Jemail Karami was torturing David’s psyche inside the ebony dome and wanted their assistance in freeing David and killing Karami. Along with Cyndi, they stormed the dome and penetrated Jemail’s inner sanctum. There they uncovered Karami’s efforts to reintegrate David’s psyche and Jack Wayne showed his true nature.

Wayne was defeated, and Xavier forced him to work with Jemail Karami to rearrange David’s shattered mindscape into a whole once again. The effort was mostly successful – David Haller emerged from his catatonic state and began interacting with the world once again. Unfortunately, he was now a boy in a body twice his mental age. Furthermore, Jack Wayne pulled a fast one and arranged for his own survival. Jemail Karami, Jack and Cyndi each remained active inside David’s mind, able to manifest their personalities and powers through David as they chose. [New Mutants (1st series) #26-28]

David became known as Legion (for he was many) and remained on Muir Island for observation and care by Moira MacTaggert. On one occasion, David was forced to unleash his telekinetic powers to save Moira and Wolfsbane from a lab accident, but in doing so he allowed Jack Wayne to take control of his body. Free to do as he pleased, Jack traveled to Scotland to indulge himself as he chose. Wolfsbane summoned the New Mutants to go after him and they engaged Jack at a local pub. Jack was forcing Cyndi to work with him, giving him access to David’s telekinetic and pyrotic powers and making him strong enough to battle the New Mutants to a standstill. Jack Wayne was finally defeated when Sunspot had Magik teleport them to Limbo. Confronted by Illyana’s dark magic and demonic realm, Wayne retreated back into the subconscious, allowing David to assume control over himself again. [New Mutants (1st series) #44]

Several months later, Muir Island had become a haven for many lost souls, including the Warpie children and the surviving members of the Morlock clan after the Mutant Massacre. Muir Island was attacked by Donald Pierce and his Reavers as part of their ongoing campaign against Wolverine and his friends. Legion was in the nursery playing with Sunder and the Warpies when Bonebreaker and his chums burst through on a killing sweep. Again, David Haller reached out with his telekinetic powers, hoping to defend his friends from harm, but again doing so allowed Jack Wayne to reach the surface of his mind. Once in control, Wayne, thought it would be amusing to reshape the telekinetic shield to protect only him, leaving Sunder vulnerable to the gunfire. [Uncanny X-Men (1st series) #254]

Jack and Cyndi continued to run wild during the attack, doing as they pleased without any thought of the consequences. Their antics continued after the U.S. government’s strike team Freedom Force arrived to help fend off the Reavers’ assault. By snuffing out Pyro’s flame at a key moment, Cyndi incidentally ensured the death of Stonewall that followed. Legion also assaulted the elderly precog named Destiny. 

Destiny had sensed him in advance and sent her protector Forge away so that he wouldn’t suffer the same fate. Legion probed Destiny’s mind, only to see visions of his own uncertain future reflected in her precognitive sight. Panicking, Legion struck out with a telepathic blast and killed Destiny before she could show him anymore. [Uncanny X-Men (1st series) #255, X-Men Forever (1st series) #2]

Amidst the chaos of the assault and the Reavers’ eventual retreat, Legion’s part in the day’s tragedies remained unknown. In fact, due to the fortifying of the island’s defenses and the overall negative emotional influence of Lorna Dane’s new powers, no one even noticed the changes in Legion. Jack Wayne had assumed control over David’s body and all of his powers, and decided to have some fun with the island’s inhabitants. He imprisoned Polaris in the Mutant X detention cell, since she was the only one unaffected by her own “negativity” force, and began making plans. [Uncanny X-Men (1st series) #257-258]

In the meanwhile, Jack continued to act like David Haller in the presence of others, and so he allowed himself to be used by Forge in an experiment to locate the missing X-Men with a Cerebro unit. Unfortunately, they made telepathic contact with something else altogether… the Shadow King. [Uncanny X-Men (1st series) #259] Seeing the heightened negative energy that permeated Muir Island, Farouk saw a fertile playground for his own personal brand of mental manipulation. Through Legion, he began to corrupt the Muir Islanders far beyond what the passive effect of Lorna Dane’s power was capable of. [Uncanny X-Men (1st series) #269]