Jack

Jack, also known as Subject Zero and by the name Jacqueline Nought, was a human biotic counted among the most powerful of her kind and a notorious criminal whose record ran to piracy, kidnapping, and murder. Made dangerous by years of experimentation she had answered with a lifetime of violence, she was held in cryogenic stasis until Commander Shepard bought her freedom and recruited her against the Collectors. Beneath her fury lay a survivor of one of the cruelest projects Cerberus ever ran, and her account is in large part the story of what she made of that. (Mass Effect 2; Mass Effect 2: Lair of the Shadow Broker; Mass Effect 3)

Subject Zero#

Jack was born in 2161 and abducted by Cerberus operatives in 2165, taken for the biotic potential she had gained from accidental exposure to element zero in the womb. As a cover, her mother was told she had died. She became the central subject of a Cerberus project at the Teltin facility on Pragia, its aim to maximize human biotic potential at any cost. Designated Subject Zero, Jack received every enhancement that proved survivable, while many other children of lesser ability were treated as expendable and died in trials meant to ensure the treatments would work on her. (Mass Effect 2; Mass Effect 2: Lair of the Shadow Broker)

She was tortured both physically and psychologically to study how pain affected her abilities, kept apart from the other children, and forced to fight them in monitored bouts while drugged, conditioned to associate killing with euphoria. The other children, dying in experiments to advance her, came to despise her as the source of their suffering. Eventually, while being led to another experiment, the children rioted, and in the chaos Jack was freed. Her powers had grown beyond anything that could stop her, and she killed nearly everyone in the facility before stealing a shuttle and escaping Pragia. (Mass Effect 2)

A violent life#

After her escape, Jack lived a bloody life. To sever ties with her past she took the name Jack and reacted violently to her old designation. She ran with gangs, became a pirate, crashed a station into a hanar moon, and at one point joined a cult. The Teltin facility was shut down soon after her escape, and the Illusive Man later claimed he had been unaware of the brutality of its experiments and had closed it once he learned of it. Eventually Jack was captured and imprisoned aboard the Blue Suns prison ship Purgatory, where the warden, eager for the price she could fetch, locked her in cryogenic stasis. (Mass Effect 2)

Recruited by Shepard#

Shepard's team came to Purgatory to buy Jack's freedom. Her ordeals had left her unpredictable and deeply distrustful, unable to determine what the Commander wanted from her, yet beneath the hostility she remained tormented by her past and longed for closure. She joined the crew in exchange for the Cerberus files detailing her experimentation, and afterward asked Shepard to help her destroy the abandoned Teltin facility by planting a bomb in the cell that had been the source of all her misery. (Mass Effect 2)

On Pragia the two fought through mercenaries and encountered another former test subject, Aresh, who had hired them to restore the facility; Jack wanted to kill him, and Shepard could intervene. They planted the bomb in her cell and escaped before it detonated. If Miranda Lawson's loyalty had already been earned, a confrontation followed aboard the Normandy in which Jack demanded that Miranda admit Cerberus had wronged her, and Shepard could side with one, the other, or neither. Whether Jack survived the assault on the Collector Base depended, as with the rest of the crew, on the Commander's leadership. (Mass Effect 2)

The psychotic biotic#

If Jack survived the mission against the Collectors, she changed considerably. Approached by the Systems Alliance, she accepted a position teaching biotics for combat at Grissom Academy and agreed to temper her language to the standard expected of a teacher. Her unconventional methods served her students well, and they took to imitating her, even bestowing on her the affectionate title "the psychotic biotic." Having never had a family, Jack came to regard her students as one and swore retribution against anyone who harmed them. (Mass Effect 3)

Jack was present when Cerberus attempted to abduct gifted students from the academy, and she defended them, shielding her charges with biotic barriers until Shepard's team broke the assault. Together with Shepard and Kahlee Sanders she helped the students escape. Over the course of the war her students were sent either to the front lines or into support roles. If Shepard did not reach the academy in time, Jack was taken and turned into an indoctrinated Cerberus Phantom, met later at Cerberus headquarters, where the squad was forced to put her down. If she lived, she fought on through the battle for Earth. Once the Crucible was fired, a Jack who had not romanced Shepard was seen either visiting her students' graves, if they had been sent to the front, or alongside her living students and Kahlee Sanders, if they had served in support; a romanced Jack was seen gazing at the stars. (Mass Effect 3; Mass Effect 3: Extended Cut)