Tantalus is a Jiralhanae warrior and member of the Concordat. He is a fierce fighter, though a better strategist and planner. He has been versed extensively in calm discussions and peaceful solutions to compensate for his former aggressive and angry nature.
Tantalus started life as a Brute living in UCR space. His father was one of few Chieftains to survive the purge of the Covenant and subsequent events that ended up leading to the near-extinction of their species. Tantalus desired to become a soldier, but his parents resisted his desires until his uncle took the initiative and helped sign him up away from the company of his parents.
Tantalus became well known within his unit, often referred to as 'Prime Ape' due to his tendency to proclaim his own strength and prowess. Tantalus is known to resist all kinds of pain, using it to fuel his aggression in combat. He used to frequent entering a berserking rage, which often required his comrades to help prevent his demise.
As time went on however, he grew patient and interested in how real commanders obtained true success. Studying these ways, he attempted to put these characteristics in place, slowly becoming less prone to enrage and more often sought a wise way to engage threats. These efforts, and their occasional success, would secure his position in the Concordat a few years later.
Tantalus was recruited into the Concordat only recently, as one of only a few dozen Brutes to actually be put in military service. He quickly rose the ranks to be the head of the entire special reserve unit of Jiralhanae in the Concordat, though his rank matches that of a mere Special Operations Sangheili.
Tantalus spent a great deal of time worrying about his homeworld and the fate of his species. He got together with many other wise Jiralhanae for ways to solve this, and planned to use his position in the Concordat to achieve his goal. Eventually, his uncle came up with the idea to find a symbol for their species, a beacon of hope that can guide the few survivors into rebuilding themselves as a primary species again.
Ultimately, Tantalus realized this symbol as the most prized, holy and sacred of ancient relics belonging to the Jiralhanae; the Fist of Rukt. After confirming its existence in the possession of the Arbiter, he met with the Prophet of Tranquility on multiple occasions to persuade him to allow him to try to retrieve the Fist of Rukt. After a long time of thinking, the Prophet ultimately granted this, and made an appointment for him to meet with the Arbiter.
Taking a team of 4 Brutes with him, Tantalus first went to the Systems Alliances' rendezvous point via CAR-Frigate, where they then boarded the retrieving CCS-Class Battlecruiser aboard their Phantom, Shadowed Tear. The Brutes then disembarked upon arrival to the Vadam Keep, where they were escorted inside to the War Room. Awaiting them were the Arbiter, alongside Kaidon Thel Chavam and Exon Speaker of the House Pavlov.
Tantalus entered a discussion with the leaders about the Fist of Rukt, prepared to undergo any trial in order to obtain it. The meeting seemed to go well despite the distrust in the Brutes, with Thel planning to put them in place to be trained in the Hellas group.
However, shortly before the meeting was to end, the War Room was suddenly attacked by the Elite Headhunter, who downed a couple guards and attempted to take down the Brutes. Tantalus' subordinates each received fatal injuries, but Tantalus did not get a chance to avenge them as Thel stepped in and stopped the fight, dealing with the still-aggressive Headhunter until he bested the intruder. Thel commanded the pair they were going to train and work together, and Tantalus, though reluctant, agreed, willing to accomplish anything to obtain the Fist of Rukt. His subordinates were soon after carried out to receive medical attention.
Thel attempted to infuriate Tantalus with various insults to show he not only didn't like Tantalus, but was trying to prove the Jiralhanae was no different than the aggressive, savage animal his species is commonly thought as. When the Headhunter regained conciousness, Thel then had the two of them engage in a lengthy duel. Tantalus succeeded in squaring off against the Sangheili with only a small cut and several small burns (the burns he allowed to happen for an unknown reason). The duel was stopped by Thel.
Later, he was directed to a training area outdoors where he was tested by a few other combatants, including Stacker. Tantalus, despite experiencing difficulty with all of them, managed to last long enough with each of them to have Thel show up and call them off, allowing him some rest.
Ultimately, Tantalus passed his assessments, and the Arbiter Thel Vadam granted him the Fist of Rukt.