Soon after having been created, Jennifer became independent due to a solar tsunami severing the link between her and the original. Still believing herself to be the original Jennifer, she was soon found along with the rest of the original team. Soon afterwards, she felt ill and was accompanied to the loo by Rory. Upon coughing up Flesh and realising she was not the real Jennifer, she hid in a stall. Momentarily unstable, she punched Rory while demanding the humans let the Gangers live.
Calming down, she decided to look for him and apologise for what she'd done. Jennifer later searched her belongings, reminiscing about her memories, and was found by Rory. She admitted she had feelings for him, and pleaded for recognition as a human and his help.
She was later present when Gangers and humans met with the Doctor to negotiate peace between them. However, the original Cleaves ruined this by killing Buzzer's Ganger. Jennifer called on her fellow Gangers not to trust the humans, fled and prepared to fight for their right to live. (TV: The Rebel Flesh)
She planned to have the Gangers kill all the humans at the factory, with the exception of Rory due to the crush she had, while she and the others posed as their counterparts and took the rescue craft to the mainland, where she then intended to incite a Ganger revolution worldwide. In the meantime, she searched for anyone left outside the monastery and left the original Jennifer for dead after throwing her off one of the towers.
Deciding to take advantage of Rory's compassion for the Gangers, Jennifer used some excess Flesh to make a duplicate of herself and injure her own leg to make it seem like she was the genuine article. Upon coming across decommissioned Gangers that had yet to lose individuality, she killed Buzzer.
Finding Rory and succeeding in getting rid of her duplicate, Jennifer tricked him into turning off the cooling systems as a human was needed to do this. Her next step was recruiting the Ganger Doctor to her side and trapping everyone else in the acid room by tricking Rory.
However, the Eleventh Doctor was able to reach the humanity in the other Gangers, causing them to abandon Jennifer's plans and free everyone. Swearing to succeed, Jennifer fled to the halls as the detonation of the factory drew ever closer.
Having now become completely insane, Jennifer altered her body into a monstrous form, killing Dicken, and attempted to kill everyone else. She was killed by the Ganger Doctor, who used the sonic screwdriver to emit a pulse that destabilised the Flesh, at the same time killing himself and the Ganger Cleaves. (TV: The Almost People)
At first, Jennifer was timid and kind like the original Jennifer Lucas. When she discovered her true nature as a Ganger, she was terrified and only desired to be acknowledged as Jennifer Lucas and to be able to live. Like her original self, she developed a crush on Rory Williams. However, after the murder of the Buzzer Ganger, Jennifer became less trusting and felt that it was "them or us" and that the Gangers had to fight to survive, even willing to murder the original Jennifer to accomplish this. (TV: The Rebel Flesh)
As time went on, Jennifer's desire for survival caused her to change from a kind-hearted, timid individual into one willing to do anything to survive. After she stopped fighting the memories of her other Gangers being destroyed, Jennifer was driven insane and began to desire to lead the Ganger race up against the humans. Her insanity transformed Jennifer into a complete psychopath who was highly manipulative and murderous. When the other Gangers refused to help murder their original selves after being reminded of their humanity, Jennifer was willing to take on the whole human race by herself. Jennifer was even willing to go so far as to transform herself into a giant monster to get her revenge. Despite her stated desire to protect the Gangers and her obvious affection for those who were thrown away, Jennifer had no remorse in creating a duplicate of herself and then destroying it just to manipulate Rory. (TV: The Almost People)
Of the Gangers who gained individuality, Jennifer proved to be the least human. While the others, even when away from their human counterparts, appeared to prefer taking on their full human appearance, Jennifer spent most of her time in her Ganger appearance. She only took on her human appearance when she was manipulating Rory. Jennifer took full advantage of her lack of humanity, manipulating and changing her body to suit her needs. (TV: The Rebel Flesh, The Almost People)