Uldren Sov is an Awoken male who is the brother of Mara Sov, Queen of the Reef. He serves as her advisor, enforcer, and spymaster. He utilizes his "Crows", agents and surveillance devices to keep tabs on the activities of other races throughout the solar system. He is more reluctant to become involved in matters outside of the Reef, which leads to disagreements with Mara. He has a strong distaste for Guardians, deeming them untrustworthy.
Using his spy networks, Uldren decrypted several Fallen communications and was able to infer that the Fallen Houses were interacting and communicating at a level never witnessed before. The Techeuns observed the arrival of Fallen towards Earth, and the Reef leadership inferred the Fallen were aiming to attack the Last City, joining in the Battle of Twilight Gap. When the House of Wolves passed near Ceres, the Awoken revealed themselves and attacked the Wolf fleet. Their attack utilized Harbingers to shatter the planetoid and killed several high-ranking members of the House, including Xiriax, Kell of Wolves. This attack was the beginning of the Reef Wars, and the remaining members of the House of Wolves scattered throughout the Reef and split into three major factions, led by Irxis, Parixas, and Skolas.
At the onset of the Taken War, Mara Sov organized a massive assault on Oryx's Dreadnaught. Its power proved too much for the Awoken armada, however, as it sent out a massive energy pulse, destroying most of the fleet. Uldren escaped alive in his fighter and crashed in a cavern located in Hellas Basin, Mars.
Later, Uldren found a dying Fallen named Fikrul and wished to save him. Riven granted this wish, corrupting Fikrul's Ether and turning him into The Fanatic. Uldren was later found by Petra Venj, who learned that Uldren believed that Mara was still alive. As a result, Petra locked Uldren and the Scorn in the Prison of Elders. Uldren persuaded Variks to free him and the Scorn, leading to Cayde-6 and The Guardian investigating the Prison. Uldren stole the Ace of Spades (Destiny 2) and used it to kill Cayde. He was hunted relentlessly by the Guardian, and was eventually killed by Petra Venj.
A few months later, Uldren Sov was revived by the ghost known as Pulled Pork and became a Guardian. It is theorized that at some point after, he reunited (unknowingly) with his sister, Mara, as stated by the Emissary's quote to the Young Wolf: "The Queen and her Hunter sends their regards", although this could possibly be a reference to Eris Morn
Uldren is knowledgeable, clever, and loyal to his sister. As a spymaster of the Reef, he has often disagreed with the Queen, but she valued his alternative perspectives. Conversely, he complied with the Queen's decisions, even when they were against his will. He is distrustful of outsiders and often comes off as arrogant and condescending to other races. His relationship with other inhabitants of the Reef can become strained due to his condescending and negative attitude. Despite his flaws, his skills in intelligence gathering and resourcefulness make him a valuable leader for the Reef.
Uldren has an uneasy relationship with Guardians. During the events of Destiny, he disagreed with giving away the location of the Black Garden, despite the threat of the Vex. Uldren disagreed with his sister's growing allegiance to Guardians and the Vanguard.
After the defeat of Oryx and the loss of his sister, Uldren has become more ruthless and cruel. During the events of Forsaken, he willingly betrays the Reef and allies himself with the Scorn in an attempt to return his sister. He was, however, tricked by Riven, Voice of the Thousands into releasing the Taken into the Dreaming City.
His current personality is unknown, as when he was revived as a Guardian, Uldren Sov lost all memory of his previous life and actions.