Alarak is a major antagonist in StarCraft II, appearing as a major antagonist turned anti-hero in the campaign Legacy of the Void.
Alarak rose through the Chain of Ascension of the Tal'darim through cunning and brute force. He would often encourage his superiors to challenge their superiors to Rak'Shir duels, as whoever died would mean Alarak would rise through the ranks.
While he was Fourth Ascendant, First Ascendant Nuroka challenged Highlord Ma'lash to a Rak'Shir duel and attempted to gain Alarak's support, but Alarak did not lend it. When Nuroka, with the support of Third Ascendant Zenish, dueled Ma'lash, who had the support of Second Ascendant Guraj, Alarak was also present at the duel, but did not declare for either side. However, after Guraj killed Zenish, Alarak entered the duel and slayed Guraj. As Nuroka began to drive Ma'lash back however, Alarak declared allegiance to Ma'lash and loaned his power to Ma'lash to help him slay Nuroka. After Nuroka was killed, Alarak was in line to become the next First Ascendant. Though Ma'lash was suspicious of him, he allowed Alarak to live as they had already lost too many high-ranking Tal'darim that day and warned Alarak not to duel him lest he suffer an even more painful death than Nuroka's.
During the End War, Alarak led a Tal'darim attack on a Khalai facility experimenting with reviving Purifier technology. Alarak's forces managed to destroy the facility, but Hierarch Artanis and his forces were able to warp out the technology just in time. After the battle, Alarak told Artanis they would meet again.
As the Tal'darim slowly became aware that Amon's true plans would not spare the Tal'darim, Alarak and several others split off from Ma'lash foces and went to ally with the Daelaam. Meeting with Matriarch Vorazun, Alarak convinced her to help him lead her forces to Artanis so they could assist him in closing a Void Portal.
Afterwards, Alarak met with the Hierarch and was able to persuade him to loan his support to Alarak when he challenged Ma'lash to a Rak'Shir duel. In exchange, Alarak promised that once he was in charge of Tal'darim he would loan their support to the Daelaam so they could exact revenge on Amon for deceiving them and betraying them. At Slayn, Alarak told Artanis that before he could challenge Ma'lash they had to take out his guardians beforehand. Alarak would later confess that slaying Ma'lash's guardians was not a part of the ritual, but stated that it was necessary to secure his rule once he took control of the Tal'darim.
After challenging Ma'lash to Rak'Shir, Alarak agreed to duel him at dawn. At first, the two combatants seemed evenly matched, but Alarak soon tipped the scales in his favor when he had Artanis' forces loan him their power. Artanis and his forces further aided Alarak by destroying the Tal'darim forces loyal to Ma'lash, which included Amon's Hybrids. Eventually, Alarak defeated Ma'lash and cast him to his death in the fiery pit, achieving the position of Highlord and rule over the Tal'darim. After agreeing to an alliance with the Daelaam, Alarak and the Tal'darim participated in the effort to retake Aiur from the Forces of Amon.
After Amon was vanquished, Alarak declined Artanis' offer to a permanent alliance between the Daelaam and Tal'darim and instead chose to leave to find a new homeworld for the Tal'darim, though he did allow any Tal'darim who disagreed with his decision one chance to remain on Aiur and join the Daelaam. Alarak soon went back to leading the Tal'darim on the path of conquest once more.
Eventually, Alarak came into conflict with the Defenders of Man when they attacked a remote Tal'darim outpost and fled before the Death Fleet could retaliate. He Struck a bargain with Nova who was pursuing the Denders herself. For his end, he led her to Jarban Minor to harvest terrazine gas to help her recover her memories and find out more about the Defenders and track them. In return, Nova would lead him to the Defenders.
Eventually, when the Defenders' war crimes were exposed to the Terran Dominion, Alarak and the Death Fleet struck the city on Vardona, with civilians caught in the crossfire. Nova declared this a dealbreaker in the bargain and join the Dominion in defending the city. The Tal-darim suffered immense casualties and were forced to retreat. Alarak accused Nova of betraying him and warned her that her actions have made him a powerful enemy. Nova mirrored the statement and warned him never to enter Dominion space again, to his amusement.