Sometime after Julian Chase was recruited into the gen:LOCK program, his Mindframe was made and copied multiple times for safety. Chase's top secret missions against the Union were extremely effective, leading to the Union taking interest in taking his Holon and his Mindframe with an ambush conducted to capture Julian. Unable to escape, he was captured but left his copied mind and body intact. In the Union, Chase's mind was subjected to torture and indoctrination.
The Union also heavily altered his Holon, likely in an attempt to both understand the technology and improve the mech for their own uses. Eventually, the Union convinced Chase, now the warped and insane Nemesis, that they could return him to his original body in exchange for his cooperation.
Four years after the Battle of New York City, the Union launched a surprise attack on the Ether data center in Dallas, drawing the attention of the Vanguard. They and the gen:LOCK team went to reclaim Dallas, and, finding minimal resistance, easily retook the city. While the gen:LOCK team was patrolling the streets, Nemesis appeared before Cameron MacCloud, who initially mistook him for Kazu Iida. Cutting off her escape with Nanotech, Nemesis effortlessly ripped off her head and began clawing away at her chest armour to get at her Mindframe, only to be interrupted by Chase - his copy. Chase was soon joined by Kazu and Yasamin Madrani, but Nemesis managed to hold them all off until the arrival of Valentina Romanyszyn, who took up a sniper position and dazed him with a well-aimed headshot. By this point, the Vanguard had arrived, including Miranda Worth. Visibly reacting to her presence, Nemesis regained his bearings and fled before the fight could continue.
Rematch in Atlanta
Sometime after the battle in Dallas, the Vanguard attack a Union base in Atlanta alongside upgraded Holons. The base is successfully destroyed, and Miranda escapes in a stolen APC with several rescued scientists with assistance from Cammie and later Yaz, only to bump into Nemesis, who recognizes Miranda and calls her by name.
He is then attacked by Yaz, fighting and knocking her away, before Cammie draws his attention. Nemesis complains that she "thinks too loud" and charges forward, only to be shot by Valentina, who was using mindshare with Cammie to see through his Nanotech wall.
Chase then arrives on the scene to fight Nemesis, the latter expressing his desire to kill his copy and uttering his old catchphrase "Let the good times roll". Chase is soon joined by Kazu, and the pair manage to rip off two of Nemesis' arms. Nemesis then flees on a Union heavy transport, despite Chase's efforts to stop him.
Attack on the Anvil
Shortly after the incident in Atlanta, the Union launches an assault on the Vanguard base "The Anvil", sending a Behemoth loaded with troops and with Nemesis in tow. Nemesis contacts the Anvil control room who recognize him as Julian Chase, and confronts Rufus Weller and Raquel Marin about them abandoning him and replacing him with a copy. Weller tries to talk Nemesis down, but he refuses to listen, and their conversation is soon cut off by Chase, who had just found out the truth behind him and Nemesis and engages his original mind in a fit of frustration.
Nemesis and Chase continued to fight each other as they get closer and closer to the Anvil. Eventually, Nemesis spots the rest of the gen:LOCK team evacuating the base with his original body. Immediately he runs after them but is stopped by the arrival of three Striders, who hold him off long enough for Chase to catch up, giving the gen:LOCK team time to escape. The two then resume the fight up until the Behemoth reaches the Anvil and begins attacking it, forcing Chase to abandon the battle and defend the base.
Remodeling and Death
As the gen:LOCK team flee the Anvil, Nemesis uses the gen:LOCK network to track them and send Union forces to give chase, taking the opportunity to taunt his copy about his lack of humanity. Eventually, the team figures out how the Union's been finding them, and Chase stops uploading, preventing the Union from tracking them.
At some point after the Battle of The Anvil, Nemesis receives an extensive redesign, further increasing his lethality, and partakes in a battle in Chicago. Soon after, he becomes aware of the gen:LOCK team uploading, and immediately flies over, reaching them in a matter of seconds. Despite the gen:LOCK team's own upgrades combined with their extensive use of mindsharing, they are unable to hold their own against Nemesis, who can predict all their movements due to his own connection with them, as well as using his upgraded nanotech to heal his wounds. Eventually, they are forced to return to their bodies before they exceed their uptime, but Chase stays back, sacrificing his body to give them time. Hearing this, Nemesis focuses his attention towards Chase and starts mocking him, telling him he still has time and inviting him to hid in Nemesis' body. Moments later, Chase exceeds his uptime, becoming trapped in his Holon, and Nemesis taunts him, claiming he is just like him. The two continue to fight, with Nemesis dominating until he is finally able to pin Chase. He continues to belittle him, but then Chase forces some of his own memories into Nemesis. At first, he is caught by surprise, but he then notices a picture with the rest of the gen:LOCK team, and decides to instead kill them, dragging a structure onto Chase and leaving him there before flying away.
Soon, he touches down in front of the ship the others are using while their uptime resets and approaches them, only to be interrupted by Miranda Worth and Leon August, the latter of whom has uploaded into Rob Sinclair's Holon. He quickly overwhelms Leon, and moves in for the kill, however, at the last moment, Miranda throws herself in front of him. Caught off guard, Nemesis is stunned long enough for Chase to return and knock him away. He attempts to go after the gen:LOCK crew again but is shot back to the ground, giving them time to upload back into their Holons. Once there, all five connect their minds, and overwhelm Nemesis with their synergy, eventually reaching into his mind and deactivating his Nanotech, which also removes his repairs and exposes his wounds. Now vulnerable, the team continue their assault on Nemesis, eventually ending with Chase dropping him from the sky, leaving him broken and defenseless.
Valentina hands their sword to Chase, who prepares to deliver the finishing blow, but not before Nemesis gives him visions of endless copies of Chase, giving his copy his dying order of killing the rest of the "copies". Chase then stabs the blade into Nemesis' chest, destroying the Holon's Mindframe and finally freeing his original mind from its suffering.