Part of his uncle's pack
Tartarus was a Jiralhanae warrior believed to have been born on the Jiralhanae homeworld of Doisac. As he had not earned his suffix yet, at this time, he was still known only as 'Tartar'. As soon as he was able, he joined his uncle Maccabeus' pack and adopted the name 'Tartarus'. Starting as a Jiralhanae Minor, Tartarus' ruthlessness and power quickly led him through the ranks up until Captain when he was aboard the Rapid Conversion, his uncle's ship.
The Rapid Conversion was originally decommissioned by the Sangheili for their own use, but was deemed worthy of use by Jiralhanae. The crew was compiled of a pack of 10 Jiralhanae, roughly sixty Unggoy and over a hundred Yanme'e responsible for Rapid Conversion's upkeep. Many of its systems, including weapons and mechanical lifts, were disabled by the Sangheili. The Sangheili did not approve of a Jiralhanae controlling a ship and as such, had crippled the ship so it could not become a threat. Although Tartarus was greatly against this, Maccabeus' faith in the Great Journey helped him turn a blind eye to this unfair treatment.
Meanwhile, near the human planet known as 'Harvest', the Minor Transgression had been boarded by the two humans Avery Johnson and Nolan Byrne. Unable to fight the two aliens, the Unggoy Dadab and his Huragok companion Lighter Than Some fled the ship, but not before sending all the data about Harvest to the Covenant's capital High Charity. Here, the Hierarchs assimilated a fleet and sent it to harvest. The Human-Covenant war had begun, although the humans did not know it yet. One of these ships was the Rapid Conversion, which on their way to Harvest intercepted the escape pod hosting the Unggoy and his Huragok companion.
As is in a Huragok's nature, Lighter Than Some started repairing the ship he was on, eventually fixing all the disabled features on the ship. This led to some great friction between the Huragok and the on board Yanme'e, as it was their task to keep the ship in good condition. As the Huragok was seen as a present from their gods, Maccabeus ordered Tartarus to protect the Huragok against any Yanme'e attack, a job Tartarus hated.
In order to learn more about their new foe, the Rapid Conversion was put on the task of making 'peace'. Tartarus was sent along with Maccabeus to the surface and participated in the feast set up by the humans. With no mutual language, the exchange was very strained, and turned sour rather quickly and soon a firefight started. At the end Tartarus came away without injury, although Maccabeus was not so lucky. As he was fighting the humans Avery and Nolan, Maccabeus' right thighbone had been shattered when the humans ran into him with a vehicle. Maccabeus had spent a lifetime delivering and receiving pain. He had an exceptionally high tolerance for it, but the agony of his cracked thighbone was almost too much to bear. Vorenus (who had been at the Spirit's controls when Maccabeus' injury occurred) had fitted the Chieftain with a magnetic splint that kept his leg immobile.
Meanwhile, the Rapid Conversion was under attack by Loki, one of Harvest's PSI AI constructs. This caused a lot of stress with the Yanme'e on the Rapid Conversion, and they began to attack Lighter Than Some. As the Huragok was already injured by the fighting on the planet, and the Yanme'e had him outnumbered 100 to 1, Lighter Than Some was severely injured. If it was not Tartarus and his spike rifle, the Yanme'e would have surely killed the Huragok. Holding the Huragok under his arm, Tartarus quickly dispatched several dozen Yanme'e, before his Chieftain ordered him to release the Huragok. Still in battle-mode, Tartarus at first did not listen. Because of his gravely injured leg, Maccabeus' patience was all but gone. Delivering a vicious swipe to his nephew's chops, Tartarus finally released the Huragok. Tartarus took a few steps back, shoulders balled in a pose that wasn't entirely submissive. But Maccabeus lacked the strength to put his nephew firmly in his place. It had been an exhausting day.
But Tartarus was not done, his blood was up. He confronted Maccabeus about the legitimacy of their search for holy artefacts. Tartarus then challenged his uncle in the ritualistic manner of Jiralhanae to a fight to the death. He made concession to his wounded opponent by allowing Maccabeus to keep his weapon and removing the ammunition from his own.
"Doubt," Maccabeus groaned, straining to keep his grip.
"Loyalty and faith," Tartarus replied, stepping to the edge of the shaft. He now held the Fist of Rukt.
"Never forget the meaning of this Age, nephew."
Tartarus bared his teeth. "Don’t you know, Uncle? This sorry Age has ended." With a powerful roll of his shoulders, Tartarus brought the hammer down, smashing the Chieftain's skull against the ladder. Maccabeus' paw relaxed.
Tartarus had successfully defeated his uncle, the Chieftain of the Jiralhanae, and thus Tartarus now bore that title, along with the ceremonial weapon, the Fist of Rukt. Later during the battle on the Tiara above Harvest, Tartarus was dealt the most insulting wound of his life when Dadab shot him with a charged plasma pistol shot. After killing Dadab with the Fist of Rukt his injury forced him to retreat and abandon combat against the Harvest Militia.
Right hand of Truth
Tartarus had gained a lot of trust by the Hierarchs, especially the Prophet of Truth. Truth regularly dismissed his Sangheili Honor Guardsman (who never left the Prophets unprotected) in order to speak to him alone. Tartarus was given information about things no High Council member had knowledge of.
One of these was the package the Covenant attack coordination station Unyielding Hierophant had been carrying. The Unyielding Hierophant had been destroyed during Operation: FIRST STRIKE, which was carrying a Forerunner artefact that was able to bend time and disrupt slipspace. Tartarus with several other pilots managed to recover three small chips of the crystal, the rest of the crystal had been lost in a explosion set in motion by Corporal Locklear, which Tartarus presented to Truth. Tartarus was instructed to reward the surviving pilots well, then execute them all quietly to ensure Truth's plans remained secret from the rest of the Covenant.
After the events of the Battle of Installation 04, Tartarus was given the task to bring Supreme Commander Thel 'Vadamee before the High Council. Thel 'Vadam was to be punished ("his fate match the magnitude of his failure.") for allowing the humans to destroy Installation 04. In front of the entire High council, Tartarus branded the Commander with the Mark of Shame and took him to the Mausoleum of the Arbiter for his execution. When the Sangheili was pardoned and promoted to Arbiter, Tartarus was obviously displeased, but kept silent out of respect for the Prophets. Tartarus was later given the task of providing aerial support to Thel 'Vadam's mission to assassinate Sesa 'Refumee on Threshold. Here, Thel 'Vadam encountered 343 Guilty Spark. Showing no respect whatsoever to the Oracle, Tartarus quickly captured it and brought it back to High Charity.
Final Acts for the Prophet
Using information gained from the Oracle, the Prophets of Truth and Mercy sent Thel 'Vadam and Tartarus on a mission to obtain the Sacred Icon on Installation 05. But unbeknownst to Thel 'Vadam, Tartarus had been given instructions to kill the Arbiter. He did this by throwing him over the edge and to his apparent death. Also on the Prophets' orders, Tartarus captured four humans: Miranda Keyes, Avery Johnson, Marcus Stacker and Marcus Banks, as they required a Reclaimer to activate the Installation. He chose Miranda Keyes to activate Installation 05 and then told his pack to kill the others.
While trying to get Commander Miranda Keyes to cooperate in the Control Room to activate the ring, Tartarus was confronted by Thel 'Vadam. Despite Thel's warnings of the betrayal of the Prophets and the 343 Guilty Spark's own account of Halo's true purpose, Tartarus remained blinded by loyalty to the Hierarchs and the promise of salvation. His hatred for the Sangheili and his desire to secure the Jiralhanae's place in the Great Journey led him to cast aside Thel's attempt to stop him, and he forced Keyes to unify the Index with Installation 05's control panel activating the ring. Tartarus declared that the Jiralhanae, not the Sangheili, would be the escorts of the Prophets to the Divine Beyond and then began to fight Thel 'Vadam and Avery Johnson, as well as numerous other Sangheili who joined the fight. Tartarus used the Fist of Rukt to devastating effect, killing many of the attacking Elites, but was eventually brought down by Thel 'Vadam after Johnson lowered Tartarus' shields with a Beam Rifle.