Xivu Arath, God of War
Xivu Arath, God of War, formerly known as Xi Ro, is a God of War and youngest sister to Savathûn, the Witch-Queen and Oryx, the Taken King. Together with her two siblings, she was a progenitor of the contemporary Hive species and one of its chief gods, having made a pact with the Worms of Fundament. She is driven to become the mightiest warrior in the universe. After the Hive's conquest of the Harmony, Xivu Arath and her Hive left her siblings for deep space, claiming Oryx had grown too powerful for her to accept.
Xivu Arath was born Xi Ro on the gas giant Fundament with her sisters Aurash and Sathona; her father was the Osmium King, ruler of the Osmium Court. She was a member of a short-lived, proto-Hive species called "krill" whose original homeworld had crashed into the gas giant millions of years ago. As a young "krill" she was fascinated by her surroundings, attempting daring feats that would have killed lesser beings; she took six of the stormjoys' bait-stars because of this. Above all she wanted to be a warrior, a Knight like her father's warriors.
When her father became mad and raved about the Syzygy, and the Helium Drinkers invaded at the urging of Taox, Xi Ro used her bait-stars to help her sisters escape and comforted Aurash as they fled their home. Together with her sisters she swore a blood-oath on the mast of their ship, upon her left eye, to avenge their father and kill Taox. When they salvaged an ancient, high-tech ship from the Shvubi Maelstrom, Xi Ro wanted to sell it to raise an army and kill Taox immediately, but was convinced by Sathona that it was worthless.
During their aimless journey at the behest of Sathona (who was guided by their father's worm-familiar) Xi Ro cleaned up the ship and attempted to take her sisters' minds off their task. Eventually, when Sathona fretted they would not be able to avenge their father, and Aurash concluded they would have to dive, Xi Ro was initially afraid but understood. Xi Ro warned them, however, that this was how the crew had died, but Sathona, urged on by the Worm, agreed with Aurash. The sisters took the needle into the deep. They finally reached a point where they could use the ship's sensors on the oceans. To their horror, they discovered that the Syzygy was real, and that Fundament's moons had already aligned. Just then, they were encountered by the Leviathan, a creature long spoken of in proto-Hive myth. The Leviathan warned the sisters that they needed to turn back, or else would unleash disaster upon the universe, saying that they faced a choice between the Light, which offered civilization, and the Darkness, which offered only violence. However, the Leviathan offered no hope to the sisters to avoid the Syzygy. Sathona then revealed the Worm's help to her sisters, and how it urged them to go down. Rejecting the Leviathan's entreaties, the sisters dove into the core.
Reaching the very center of Fundament, the three sisters found the Worm Gods: Akka, the Worm of Secrets, Eir, the Keeper of Order, Ur, the Ever-Hunger, Xol, Will of the Thousands, and Yul, the Honest Worm. The Worm Gods offered the three sisters a chance for the proto-Hive to escape Fundament as well as achieve immortality. All they had to do was take the Worms larvae into them as symbiotes and spread them among the proto-Hive. The Worms posed the caveat that the sisters must never cease their natures: Xi Ro must always test her strength, Sathona must always be cunning, and Aurash must always try to understand. The sisters accepted the pact and became the first Hive: Xi Ro took the Knight morph and became Xivu Arath, Sathona took the Mother morph and became Savathûn, and Aurash took the King morph, transforming into a male and became Auryx, the King of the Hive.
Campaign of Destruction
As Auryx and his sisters forced an ultimatum on the remaining proto-Hive to accept the worms or perish, Auryx turned his attention to Fundament's moons, and the Ammonites there who had allied with the Traveler and gave asylum to Taox. Initially he was willing to negotiate with the Ammonites, but his sister Savathûn, under pressure from the Worms, killed Auryx as punishment. Rather than dying, Auryx's soul instead passed to his Ascendant realm, or throne world, where his soul resided until he returned to the mortal realm. Rebuked, Auryx purged what sympathy and goodwill he had left, becoming a merciless tyrant. He and his sisters warred with and killed one another on a regular basis after the defeat of the Ammonites, as part of their worship of the Sword-Logic and their attempt to become the sharpest blades in the universe, heading to their Ascendant realms when defeated. Their war of revenge against Taox had transformed into a campaign of genocide, when they slew the Ammonites and other interstellar civilizations to feed their worms. While Oryx and Savathûn established courts to practice and study the sword logic, Xivu Arath declined, declaring that her court would be everywhere war was found.
During the war with the Ecumene, Auryx came to realize that the Worm had deceived him and his sisters: their Worms appetites were growing past their ability to feed with death. Meeting with his sisters in his ascendant realm, surrounded by their servants (some of which despised them for showing weakness) they despaired over their dilemma. When his sisters offered their power to help Auryx find a way to save them, Auryx killed them, then used that power to confront his patron god Akka, the Worm of Secrets. He killed Akka so that he may steal its ability to call upon the Deep and created the Tablets of Ruin, which gave him the power to Take. His transformation complete, Auryx was now Oryx, the Taken King. During the subsequent war with the Ecumene, Oryx revived Xivu Arath in an act of war, and revived Savathûn in an act of cunning. He then decreed the tithe system: each Hive would kill their enemies, take some to feed their own worm, and tithe the rest to their superior. Thralls would tithe to Acolytes, Acolytes would tithe to Knights or Wizards, the Knights and Wizards would tithe to the Ascendant Hive, those who commanded legions of warriors and earned the right to enter the Hive gods' Ascendant realms. All of this violence would eventually reach Oryx, Savathûn, and Xivu Arath, allowing their worms to feed on violence while continuing to invoke their inner natures.
Following the Golden Amputation, Oryx declared to his sisters that the Hive had conquered its way to the edge of the Deep, and that it had granted him a personal audience.  As Oryx retreated into his throne world to commune with it, Savathûn conspired with Xivu Arath to strand him there and steal his Tablets of Ruin by cutting off the tribute flowing through his tithe system.  They were ultimately unsuccessful. On returning, Oryx deceived Xivu Arath and poisoned her own flow of tribute so that she could never try to steal his Tablets again.
In the aftermath of this attempted betrayal, one of Oryx's daughters, Ir Halak, visited Xivu Arath's throne world and tested her Deathsong there. All who heard it were irreversibly killed. Xivu Arath complained about Ir Halak's behavior to Oryx, who was greatly amused. 
After the Vex invaded Oryx's throne world, Savathûn tipped Xivu Arath off as to its location. Xivu Arath planned an ambush, but Oryx, aware of his own vulnerability, evaded her by moving his throne into the Dreadnaught. 
Following the war with the Harmony, Savathûn decided that her fleets would enter the black hole that the Harmony lived around, claiming that they would become stronger for it, while Xivu Arath took her fleets away from Oryx's as she felt he constrained her too much.
The Dreaming City
Following the death of her brother Oryx and two years later, after the Red War, Xivu Arath began committing her forces to the Solar System, possibly in aid of her sister Savathûn or for her own schemes. An Ogre, Megor, Spawn of Xivu, (who is possibly Xivu's child), was imprisoned in the Prison of Elders and broke free during the Scorn's jailbreak. A substantial force of Hive and Taken apparently obedient to Xivu Arath also invaded the Dreaming City after its unsealing, pillaging it for Awoken relics towards an unknown purpose. These forces were destroyed by The Guardian and the relics returned to the Awoken.
List of appearances