The human-manufactured robot known as Nemesis Prime is a mindless drone created by MECH, controlled remotely by a human operator. In order to cause psychological, as well as literal, damage, the machine was built in the exact likeness of Optimus Prime, the leader of the Autobots. Nemesis is capable of operating as both a semi-rig truck and a humanoid combat robot with the same strength, agility, and firepower as the original article, except with MECH leader Silas in control. Having no mind of its own, it therefore has none of Prime's moral strengths, and also lacks any form of pain receptors, making it an utterly merciless killer.
Nemesis Prime was the culmination of MECH's Project Chimera, an almost exact copy of Optimus Prime controlled by Silas from MECH's base of operations. In preparation for Nemesis Prime's creation, MECH took a complete scan of Optimus Prime's body and abducted and analyzed Breakdown's body components.
To finalize the prototype, MECH stole Bumblebee's T-cog and installed it in the robot. The first attempt to create Nemesis Prime, however, was less than a success without access to Energon. They were helped by Starscream, now a rogue, who approached MECH with a deal to give them access to Energon so long as Starscream had a share of it. Operation Bumblebee, Part 1 After finding and processing some Energon, the Nemesis Prime prototype began to work. But a vengeful Bumblebee stormed the base and took back his missing part, heavily damaging the prototype in the process. To compensate for his loss, Silas turned on his ally, taking Starscream's T-cog and installing it into Nemesis Prime's body.
On its first excursion, Nemesis Prime attempted to ram Agent Fowler off a bridge, but retreated when the Autobots arrived on the scene. Arcee followed it into an abandoned petrol station when Nemesis blindsided her, knocking her unconscious. It later attempted to frame Optimus Prime and the Autobots by transforming and attacking Alden Military Base. It made another retreat when the real Autobots showed up, though the damage was done: many of the base's vehicles were destroyed and the blame was on Optimus Prime.
Nemesis Prime next confronted the Autobots when they were closing in on MECH's base, taking them out one-by-one. Optimus confronted it in combat after the other Autobots had been defeated. After a lengthy battle, it seemed that Nemesis Prime had the advantage since it was impervious to pain. But before Nemesis could finish off his foe, Silas had to vacate the robot's control chair to battle Agent Fowler, who had made his way into the building and taken out the other MECH members in the room. Nemesis was left immobile in the interim, allowing Optimus to gain the upper hand. After defeating Fowler, Silas desperately jumped back into the chair, but was too late. Optimus smashed Nemesis through the roof of MECH's base, crushing both the equipment controlling it and Silas himself. The heavily wounded MECH leader was pulled to safety by his men.
Nemesis Prime's body was placed in storage by the military. General Bryce mistook it for Optimus Prime and believed the Autobot leader was dead. He abruptly changed his mind during Fowler's testimony when he had an unscheduled face-to-face conversation with Optimus.
Nemesis Prime is capable of operating both in a semi-truck and a humanoid combat robot with the same strength, agility and firepower as the real Optimus Prime. Only one exception is with the MECH leader Silas in control of Nemesis Prime, as having no mind of its own, it has none of Prime's moral strengths and lacks any form of pain receptors, making it an utterly merciless killing machine