Nothing is known of Aziel's life before he became one of Sokar's four chief underlords, but in this role Aziel was charged with managing the day to day affairs of Sokar's most important planets. While, being simply an underlord, Aziel was only a minor Goa'uld in the grand scheme of the Goa'uld Empire, Aziel played a key role—gatekeeper—throughout Sokar's realm. Having taken a brooding hulk as his Human host, who had a scar down his face and a stature that made many suspect he could stand toe-to-toe with an Unas if the need called for it, Aziel appeared to be an imposing individual. In addition to this, Aziel was known to wear a modified version of Necropolis Guard armor which, while still tinted red, was re-sized to cover his massive frame and boasted a pair of decorative razor-sharp "wings" which protruded from the back of the armor to add to his demonic imagery. To complete this ensemble, Aziel wielded both a kara kesh—having been granted the honor of doing so by his master—and a customized staff weapon which was adorned with an inscription identifying him as Sokar's gatekeeper.
Utterly devoted to his master Sokar, Aziel maintained an attitude of strict terror and discipline among the people of the worlds he governed. If Aziel had one weakness, however, it was that he had such a strong sense of vengeance that he was known to forgo the logical solution to a problem so that he could make his enemies suffer, and frequently left his First Prime to command in his place while he left to hunt down someone whom he perceived to be an enemy. Though Sokar warned him about this trait, he continued his habits out of a perverse need to make those who stood against him, or his master, suffer.
Despite Sokar's death at the hands of the Tau'ri, Aziel continued to serve his master in the same way he had always done and managed to thwart several attempts by other System Lords to claim Sokar's territory as their own, including those of Apophis and Kali. Though he could very well have claimed the title of System Lord for himself during this period, he did not do so due to his sense of loyalty to Sokar, as well as the fear of what would happen should his master return from the dead. (RPG: "Living Gods: Stargate System Lords")