Shift was a clone of Miles Morales created by the Assessor. He was trained and tortured by the Assessor, who ultimately advanced his age by force. He plotted together with his brothers, Selim and Mindspinner, to break out, as soon as they were strong enough.
Shift was created in Miles Morales: Spider-Man #25 by Saladin Ahmed and Carmen Nunez Carnero during Miles' own Clone Saga.
Major Story Arcs
Shift followed his brother, Selim, on various heists and kidnappings looking for science equipment and scientists. They realized they were suffering from cellular degradation and would not last much longer without a cure.
When these crimes gave Miles a bad reputation, he started investigating them. He tracked them to a lab where he thought they were making more clones, so he destroyed it. To get back at him for destroying their cure, Selim and Mindspinner targeted his family, while reluctant Shift guarded Miles.
Miles recognized Shift's reluctance to hurt him and tried to make an emotional connection with him. He was able to break free of his restraints and leave without Shift trying to stop him. Meanwhile, Selim used Billie to bait Miles to the Brooklyn Bridge. Selim engages in combat to prove he is better than Miles. Eventually, Mindspinner and Shift show up, but when Shift proves to be on Miles' side, Selim attacks him. Mindspinner defends Shift leading to Selim and Mindspinner using their venom blasts on each other and causing a large explosion.
With his brothers dead, Shift is invited to join Miles' family. Shift wasn't ready to meet the family, but Miles still got Ganke's help in checking out his disease with stolen school equipment. They determine that when Billie sneezed on Shift, it forced his immune system to create antibodies that also somehow stabilized his clone form.
Miles is served papers by the Beyond Corporation, for misuse of the Spider-Man trademark that Beyond owned. He continued using it anyway, and Ben Reilly, Beyond's in-house Spider-Man supported Miles' choice to defy the legal notice. After their team up together, Miles found evidence that Assessor might be working on new experiments with Beyond's help. So, Miles and Shift went to investigate.
They found the main hard drive where Assessor kept his A.I. The Assessor created a number of drones to take them on, so they needed help from Quantum, the Assessor's henchman. Quantum was sick of being torture as a Beyond test subject so he teleported Miles to the top of the large hard drive where Miles used a venom blast to overload it, wiping the Assessor.
Quantum left but told Miles to check the black doors. He found files on alternate universes including a report about Aaron being alive. Using a Beyond portal, he and Shift went looking for their Uncle Aaron. They ended up on a fascist dystopian Earth when Selim had survived and taken over. An older Ganke was part of a resistance that helped Miles and Shift take out Selim and rescue Aaron, who was Selim's prisoner, eventually making it back home through the portal.
Metamophic: Shift's body is very unstable allowing him to morph and stretch.
Immunity: He is immune to Miles' venom blasts.
Chemical Secretion: He is capable of secreting a multi-color knockout gas that also doubles as spray paint.