The very definition of deceit, avarice, and gluttony, he was known for his many appetites. He was also known as an inventor, and he claimed responsibility for inventing a lot of Goa'uld technologies, including the Goa'uld holographic projector, a system to disable the Correlative update system of the Dial Home Device, and the means to activate multiple Stargates at once, the latter of which, he insisted, was what had made it possible to defeat the Replicators, as he says he did for Ba'al during the Goa'uld conflict with the Replicators.
Nerus contacted Stargate Command with an obsequious message claiming that it would be a great honor to meet "the heroes of the Tau'ri who brought the Goa'uld to their knees" and that he had intelligence of the utmost urgency to aid Earth in the battle against the Ori. Nerus was eager to meet Teal'c (the Jaffa responsible for the original uprising) and the rest of SG-1, despite the fact that he had been fighting against them for many years, and was actually quite disappointed that Major General Jack O'Neill and Lt. Colonel Samantha Carter were no longer with SG-1. Teal'c was aware of him and saw no reason to why he could not be brought through the Stargate to Earth. Despite Vala Mal Doran's warning that he was not to be trusted, Nerus was permitted to come to the SGC, and at his request, a feast was prepared in exchange for his information. Although his dietary requirements included ripened trakeel eggs, he discovered that seedless grapes and chicken were a more than adequate substitute. Nerus had brought word that the Ori invasion had begun on Kallana where a force field had begun to expand across the planet, and he urged that Earth must attack the energy field with the most powerful weapons in their arsenal.
Following his advice, SG-1 detonated a Mark IX warhead on Kallana, but only after the weapon's energy caused the force field to envelop the entire planet did it become evident that Nerus had deceived them from the start. He had become an agent of the Ori, confident that one day he would share their power and ascend. Knowing that the Ori attempt to create a beachhead required additional power, he had encouraged SG-1 to play into their hands. The Ori invasion at Kallana was prevented, however by Vala's efforts. Afterward Nerus openly admitted his treachery to Major General Henry Landry, looking forward to being sentenced to death, thereby ascending to the Ori. Instead, Landry ordered that Nerus be taken into custody and incarcerated in a small dark room in the basement of Area 51 where he would stay until hunger compelled him to devise a defense against the Ori. (SG1: "Beachhead")
Seven months later, in February 2006 when Stargates were being stolen across the galaxy, Major General Henry Landry visited Nerus at his cell at Area 51 and once again offered him a feast in exchange for information. Over turkey, soft pretzels, pizza, assorted breads and cheeses, twinkies, and individually frosted cakes, Nerus confirmed that Ba'al was behind the theft of the Stargates. By putting Nerus's research into practice and disabling the Correlative update system so that Stargates could be moved without transmitting their new coordinates to the rest of the network, Ba'al had begun to steal Stargates from dozens of planets with the intention of rebuilding his empire. Landry provided a deception of his own and offered Nerus his freedom in exchange for Ba'al's location, then he allowed Nerus to leave through the Stargate with a sizable assortment of his favorite cupcakes, secretly tagged with tracking beacons, and a trojan-like computer virus programmed into his devices thanks to Dr. Bill Lee, viruses that would disable any systems to which they were connected.
Using the subspace beacon, the Odyssey was able to trace Nerus to Ba'al's Ha'tak where his many clones had been gathering the stolen Stargates. Ba'al was distrustful of Nerus's dealings with the Ori and the Tau'ri, and his suspicions were only confirmed when Nerus's devices caused the ship's systems to fail, providing SG-1 with the opportunity to beam aboard. SG-1 succeeded in tagging the dozens of Stargates in the ship's hold with locator beacons and making their escape through one of the on board Stargates just as the Odyssey beamed the stolen gates aboard and Ba'al's ship was targeted by the Lucian Alliance. With the Ha'tak systems on the fritz, Ba'al logically deduced Nerus was the problem and immediately Ba'al summoned Jaffa, and headed straight to Nerus' quarters. Nerus was shot, and presumably killed, by a staff weapon fired by an angry Ba'al or one of his clones. Even if Ba'al had not killed Nerus permanently, Nerus and the Ba'al clones perished when the Ha'tak was destroyed by the Lucian Alliance. (SG1: "Off the Grid")
- His final line, "But I'm so interesting." parallels the sentiment of the Roman emperor Nero's purported last words, "Qualis artifex pereo." (roughly, What an artist dies in me).