Zalmamdar was originally named Callisto Ferrer, and he was a member of NEXUS back when it was a smaller group led by the Sheriff.
Later, after the group was renamed the "Agency Against Hank Wimbleton", Callisto was approached by new leader of the organization, the Auditor. Recognizing Callisto's high intelligence, the Auditor offered Callisto co-ownership of Project Nexus. Upon agreeing, Callisto was engulfed in black flames and transported to a tube. He was then pulled out by two men and taken to a magnified Phobos, who gave Callisto a position in his new order and renamed him "Zalmamdar Oox".
After being given a position as head scientist Zalmamdar discovered the Auditor's true origins. He was one the Employers, beings who betrayed an entity known as the High and stole its powers.
Zalmamdar began to secretly plot against the Auditor and free the High from the Employers. He cut off his hand and used his DNA samples to create multiple clones of himself, the first of which he named "Kelzad". Zalmamdar also came across an imprisoned grunt named August Huffman who suffered from several mental illnesses and incorporated him into his project, renaming him "Yeelon Mekyr".
Yeelon's tube later mysteriously exploded, freeing him and Kelzad. The two A.T.P. Grunts then tried to escape, fighting their way through many l33t Agents and A.T.P. Engineers. Zalmamdar tried to approach them and offer his hand to them. However, Yeelon began to shake violently, cut off part of Kelzad's head, and fly out the building.
Zalmamdar later revived Kelzad, and sent him into an arena to test his fighting skills. However, after defeating several Grunts, Kelzad attempted to escape again. Yeelon also reappeared and possessed several of the A.A.H.W. soldiers. Yeelon transformed into a demon face and grabbed Kelzad, but Zalmamdar and several A.T.P. Engineers and Agents appeared and shot at Yeelon, making him drop Kelzad. Zalmamdar then offered his hand out to Kelzad again, which Kelzad accepted.
Zalmamdar later gave Kelzad a weapon he had developed to fight the Employers called "the Charger". When Sokar attacked again, Zalmamdar and Kelzad fought their way through Yeelon's possessed minions. They later split up, with Kelzad going to confront Yeelon.