Indo Zal was a Human male, a citizen residing within the Eternal Empire of Zakuul. Orphaned early in life, he was raised by his sister, Kalya, a Scion of Zakuul, who met her end at the hands of High Justice Vaylin during the tragic Scion massacre. Driven by a thirst for vengeance, Indo strategically integrated himself into Vaylin's inner circle, becoming her Magistrate of Revelry, all while secretly plotting her downfall. In the year 3630 BBY, he played a pivotal role in assisting the Alliance Commander and Theron Shan to infiltrate the Grand Festival of Empress Vaylin, providing them with ion charges that would disable the shock collars hindering the captured Zakuulan rebels, enabling them to join the fight against Vaylin. His duplicity was exposed, leading to his impending execution alongside the rebels, only to be rescued by the Alliance Commander. Following their escape from the destruction of the Palace of the Eternal Dragon, Indo took the lead in guiding the rebels to support the Commander during the climactic Battle of Zakuul.
At the tender age of six, Indo experienced the loss of both his mother and father, both esteemed Knights of Zakuul, during the Battle of Scyva. His upbringing fell to Kalya Zal, his elder sister and a respected member of the Scions of Zakuul. She imparted the virtues of patience and taught him the art of influencing others, emulating the Zakuulan elite, and navigating the complex social landscape of the Eternal Empire. Indo ascended to the position of Magistrate of Revelry, overseeing opulent cruisers, orchestrating grand festivals across planets, and generally relishing his role as Zakuul's foremost entertainer. A career highlight was his presiding over the execution of High Justice Yuriem.
Following the assassination of Valkorion in 3636 BBY, his son Arcann seized the Eternal Throne and initiated the Scion massacre, a horrific event in which Indo's beloved sister was put to death by Arcann's sister, Vaylin. Consumed by grief, Indo yearned for retribution, but chose a more calculated approach, gradually ingratiating himself into Vaylin's service, eventually becoming her personal attendant when she became Eternal Empress. Throughout this time, Indo harbored the desire to bring about her downfall. In 3631 BBY, he played a part in helping Lana Beniko's astromech droid, T7-O1, infiltrate the Spire. Ultimately, Indo established contact with the Alliance based on Odessen and actively worked towards removing Vaylin from power. Indo provided Beniko, Theron Shan, and the Alliance Commander with information about the upcoming Grand Festival of Empress Vaylin, suggesting the use of the rebels Vaylin intended to execute as a means for the Alliance to get closer to her. Indo supplied the shuttle, Zakuul Knight disguises, and security clearances that were utilized by Theron Shan and the Commander to infiltrate the Palace of the Eternal Dragon.
As the festivities commenced, Indo assured Vaylin that the party guests were toasting her name and that the rebels were fitted with shock collars. He then convened with his accomplices, outlining the next phase of his plan. He furnished them with ion charges to be attached to security relays throughout the Palace, enabling their simultaneous detonation and disabling the rebels' shock collars. Tasking the Alliance with this endeavor, Indo returned to Vaylin's side, only to be discovered spying on her during a conversation with Jarak, which exposed his treachery and resulted in him receiving a collar of his own. Vaylin delivered a speech, vowing to execute Indo alongside the rebels, but was interrupted first by the Alliance Commander and then by the former Emperor Arcann. Indo and the rebels were cast into the beast pit, but the Commander and Theron Shan successfully rescued them from a gruesome fate. Subsequently, the Commander instructed Indo to lead the Rebels to safety, a decision that proved fortunate, as Vaylin ordered the Eternal Fleet to bombard the Palace into ruins, disregarding the presence of her supporters within.
Indo eventually reached a secure location and transmitted a message to the Alliance, relaying his current status. Vaylin was soon killed during assault on Odessen, an event that triggered the GEMINI captains of the Eternal Fleet to go rogue and establish a blockade around Zakuul. Upon the Commander's return to Zakuul to claim the Eternal Throne, Indo and the rebels lent their assistance at the Garden of Izax, employing Missile launchers to obliterate several Eternal Empire Walkers. Following the Commander's ascension to the Eternal Throne and the proclamation of the Eternal Alliance era, Indo personally oversaw the celebratory gathering, which he deemed his finest to date.
During Chapter VI: The Dragon's Maw of Knights of the Eternal Throne, players have the option to make a Dark Side choice, directing Indo to lead the rebels against the Knights instead of guiding them to safety. Should this occur, Indo will sustain an injury, send a message from a hospital rather than a hideout, and during Chapter IX: The Eternal Throne, it will be noted that the Rebels have lost faith in the Alliance.
If the player embraces the Dark Side choice to address the galaxy as the new Emperor at the conclusion of Knights of the Eternal Throne, the "The Nathema Conspiracy" flashpoint will reveal Indo's regret over his decision to trust the Commander, acknowledging it as a lapse in judgment. Seeking to free his people from Alliance control, Indo aligns himself with the Order of Zildrog, led by former Horizon Guard Vinn Atrius, only to be sacrificed as fuel to awaken Zildrog by GEMINI 16 on Nathema. Conversely, if the player chooses the Light Side option to address the galaxy as a peacekeeper, Zakuulans are granted the freedom to govern themselves, and Indo Zal has no motivation for revenge, his role as Zildrog's victim being assumed by Darth Mortis instead.