Following the Eternal Empire's defeat on Zakuul, a combative group known as the Order of Zildrog arose. Vinn Atrius, seeking retribution for his people's downfall, united disparate individuals and factions, all sharing a deep-seated animosity towards the Alliance and the Commander leading it. After discovering information about Zildrog, an ancient superweapon originating from Iokath, Atrius learned about its mechanics and location from GEMINI 16. This rogue GEMINI unit, desiring the destruction of the Eternal Fleet, provided the Order with the means to potentially dismantle the Alliance.
Theron Shan, a founding member of the Alliance, became aware of the Order's existence and resolved to undermine it from within. Shan orchestrated a ruse on Iokath, luring the Commander into a trap, and later revealed his apparent treachery during the mission on Umbara. By feigning allegiance to the Order, Shan deliberately fed them deceptive information while covertly pursuing Zildrog's location. His quest led him to infiltrate the Chiss House Inrokini on Copero to obtain the Sith Emperor's holomap that would lead him to it. After the Order located Zildrog on Nathema, Theron dispatched an encoded message to the Alliance, arranging a meeting where he disclosed his true loyalty and intentions.
Theron, along with Lana Beniko and the Commander, made an attempt to prevent the Order from awakening Zildrog, but their efforts were in vain. Confined within a force field, they were helpless witnesses as GEMINI 16 activated Zildrog, revealing its alternate form as the Gravestone. This crucial Alliance asset, stationed on Odessen, was then remotely commandeered by Zildrog to systematically obliterate the entire Eternal Fleet, which remained idle in Odessen's orbit without command directives. As Zildrog prepared to target Odessen itself, the Alliance leadership seized an opportunity to engage and eliminate GEMINI 16, defeat Vinn Atrius, and ultimately destroy Zildrog. Despite failing to achieve its ultimate objective, the Order inflicted a significant blow to the Alliance, depriving them of vital military resources and prompting numerous members to abandon the cause in the aftermath.
Around 3630 BBY, the Eternal Alliance concluded the war against Zakuul on Zakuul by overthrowing the Eternal Empire and appropriating some of its military assets. The most important of these being the Eternal Throne which controlled the Eternal Fleet. Following this conquest, Vinn Atrius, a former member of Empress Vaylin's Horizon Guard, observed the suffering of his people and the war's devastating impact. He developed a deep resentment towards the Alliance and its Commander, who had brought an end to Zakuul's long period of prosperity under Emperor Valkorion. Driven by a desire to avenge his people, Atrius resolved to dismantle the Alliance and began searching the GEMINI network for the means to achieve this goal. While examining data the Eternal Empire obtained on Iokath, he discovered mentions of Zildrog, an ancient dragon god from Zakuulan folklore. The data suggested that Zildrog was actually an Iokath superweapon with the capacity to destroy entire civilizations. Atrius then initiated a search for a way to locate, awaken, and control Zildrog.
Atrius established the Order of Zildrog, recruiting Zakuulan hardliners, including former Horizon Guards, Knights and Scions of Zakuul, Eternal Empire military personnel, reprogrammed skytroopers, and fringe cultists from the Heralds of Zildrog. United by their hatred of the Commander for destroying their civilization, the secretive Order initiated a campaign to bring about the Outlander's downfall and the demise of their Alliance. They established a base of operations at an abandoned listening post, where GEMINI 16 approached Atrius, promising to share information about Zildrog in exchange for the destruction of the Eternal Fleet. GEMINI 16 gained access to the security systems of the Alliance base on Odessen, enabling the Order to observe and record the Alliance's every move for months.
Theron Shan, a key founder of the Alliance, contacted Atrius, expressing his desire to join the Order and bring down the Alliance. Atrius initially dismissed him, prompting Shan to orchestrate a trap for the Commander on Iokath to demonstrate his commitment. He then re-established contact with Atrius, asserting that his contributions were essential to the Order's success. Atrius remained skeptical of Shan, pointing out that the events on Iokath had provided the Alliance with a powerful ally, whose support was now unavailable to the Order. Shan requested an opportunity to prove himself, and Atrius tasked him with securing a shipment of adegan crystals from Umbara. Theron traveled there alongside the Commander and Lana Beniko and revealed his apparent betrayal, trapping them on a train destined for a collision with a mountain. While the Commander and Lana survived the crash, Theron successfully secured a significant portion of the adegan crystals shipment, escaping on his shuttle.
Impressed by his apparent dedication to their cause, Atrius and the other members of the Order decided to accept Theron Shan into their ranks. Leveraging his unique infiltration skills as a former Republic Strategic Information Service operative, they assigned him the task of locating a holomap containing the coordinates to Zildrog's location, although GEMINI 16 cautioned Atrius against trusting Shan. Theron discovered a lead on the device, which had been stolen by Chiss agents from the Sith Emperor on Copero. He then persuaded Zenta, the ruling Syndic of House Inrokini, to grant him refuge in exchange for Alliance secrets. Zenta's brother, Valss, possessed Force-sensitive abilities and experienced a vision of Shan's victory, leading him and several of Zenta's elite fighters to join the Order. Theron accessed Zenta's personal datapad to uncover the map's location within the ancient ruins and abandoned the Syndic. He and Valss extracted Zildrog's coordinates and destroyed the holomap, but as they prepared to depart, the Commander and Raina Temple arrived to intercept them. Valss remained behind to provide cover, sacrificing himself, while Theron escaped on a shuttle and transmitted the coordinates to Atrius.
Using the information from the map, the Order determined that Zildrog was located on Nathema and relocated their base of operations there. They salvaged what they could from the listening post and tasked Theron Shan with erasing all data and destroying the remaining infrastructure. However, Shan was actually a double agent working for the Alliance and secretly created encrypted backups of the data, along with a message intended for the Alliance. As he anticipated, the message was intercepted, prompting the Alliance Commander and Lana Beniko to travel to Nathema. Meanwhile, the Order excavated Zildrog from the ruins of an ancient Sith Temple, with the assistance of allies who harbored personal grudges against the Commander.
Theron managed to slip away from the Order and rejoin his allies, but GEMINI 16 detected their presence, and Atrius ordered the ritual to awaken Zildrog to commence ahead of schedule. The GEMINI unit deceived and betrayed some of their allies, confining them within energy transfer chambers to be used as fuel for Zildrog's awakening. As the Alliance engaged the Order's forces in battle and reached Zildrog's location, Shan shot Atrius. However, GEMINI 16 trapped the Alliance members within a force field and revealed that the machine god had already been awakened. Zildrog then exploited its connection to the Dark Sanctuary to remotely seize control of the Gravestone, which was stationed at the Alliance capital of Odessen. Zildrog maneuvered the Gravestone into Odessen's orbit and proceeded to repeatedly fire its omnicannon at the Eternal Fleet, which remained defenseless due to the absence of orders from the Eternal Throne.
After obliterating the Eternal Fleet, Zildrog turned its attention to Odessen itself and began recharging in preparation for its next attack. It dropped the force field, forcing GEMINI 16 to directly engage the Alliance. Lana, Theron, and the Commander fought and destroyed the GEMINI droid. Theron attempted to shut down Zildrog, but Vinn Atrius stabbed him in the back with a lightsaber pike. Desperate for revenge, Atrius commanded Zildrog to enhance him with its power, after which he attacked Lana and the Commander with his newfound strength. The two of them defeated Atrius and destroyed Zildrog, but this final act also triggered the self-destruct mechanism of the Gravestone and disabled the Eternal Throne. The Alliance had lost two of its most potent weapons but managed to survive, while the Order of Zildrog was effectively destroyed, leaving the Commander to determine Vinn Atrius's fate.
The membership of the Order varies based on the player's class and the choices made throughout the base game and the Knights of the Eternal Throne expansion. During "The Nathema Conspiracy" flashpoint, three individuals appear as Zildrog's victims. Two of these characters are introduced in holorecordings on the abandoned listening post, while the third confronts the player before the second boss fight of the flashpoint:
- Either Chela Nayss or Zera, depending on the player's decision to support or attack Senya Tirall during Knights of the Eternal Throne Chapter I: Wrath and Ruin. [2]
- Either Darth Mortis or Indo Zal, depending on the player's decision to claim the Eternal Throne as a peacekeeper or as the new Emperor during Knights of the Eternal Throne Chapter IX: The Eternal Throne. [2]
- For Jedi Knights, either Servant One or Bela Kiwiiks depending on the player's alignment with the Light or Dark side. [2]
- For Jedi Consulars, either Sophia Farash or Gaden-Ko depending on the player's Light or Dark alignment. [2]
- For Troopers, either General Essith or Elin Garza, depending on the player's choice to support either the Republic or the Sith Empire during the War on Iokath. [2]
- For Smugglers, either Nexia Kirill or Jedi Master Sumalee, depending on the player's decision to pledge the pirate fleet to the Republic or claim them for personal use towards the end of their class story. [2]
- For Bounty Hunters, either Malea Janarus or Sith Lord Vindis, depending on the player's choice to kill Dorian Janarus or Darth Tormen towards the end of their class story. [2]
- For Imperial Agents, either Shara Jenn if the player became a double agent for the Republic Strategic Information Service, or Marcus Trant otherwise. [2]
- For Sith Warriors, either Darth Baras or Darth Ravage, depending on the player's choice to spare or kill Baras towards the end of their class story. [2]
- For Sith Inquisitors, either Darth Zash or Khem Val, depending on the player's choice to imprison one of them in the Mind prison towards the end of Khem's companion story arc. [2]