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Mothership is a StarCraft II short web story written by Mass Effect 2 writer Brian T. Kindregan, set in the StarCraft universe and designed to tie-in with Wings of Liberty. It focuses on the mothership unit.
As Aiur fell to the zerg, high templar Erekul guarded a locked chamber, from which he would summon the dormant motherships at the edge of space known to the protoss. The zerg burst into the room after the signal was sent. Erekul destroyed some with a psionic storm, but they caught up to and killed him.
Juras, designer of the mothership, awoke alone on his prototype, the Moratun, after a long dormancy. He had expected this to happen when the protoss made contact with another advanced species, which he believed would be more interested in trading ideas than violence. Upon hearing the brief message to return to Aiur, he assumed the Khala and the Conclave could surmount any problem.
Juras unwillingly recalled his time during the Kalath Intercession. When the kalathi civil war erupted, he suggested the executor fire a powerful weapon of his own design to frighten the aliens. However, kalathi bloodreavers began to attack the protoss, and by the time the war ended, the protoss had deployed colossi and hundreds of thousands of kalathi had died. Juras was determined to avoid this kind of genocide again.
As the Moratun appeared near the colony of Samiku for a course correction, the leaderless zerg rampaged the low-worth colony. Commander Martul led zealots in defense, but had been cut off from reinforcements from Aiur. Juras observed the zerg, noting their intelligence had been lost. He contacted Martul, who demanded he destroy the zerg to rescue her warriors. Juras, reluctant to attack another sentient species, nonetheless complied and went on to rescue the zealots. However, he refused to continue the battle, preferring to speak to the Conclave. Martul threatened to take over the ship, but Juras wouldn't allow it. He said he wished to avoid another genocide and wished to learn more about the zerg, an attitude which the war-hardened Martul scorned.
The Moratun descended into Aiur's cloud layer, falling under attack by the zerg. As its shields fell, Juras and Martul continued to argue. Martul threatened to kill Juras, but he had locked the weapon systems. As they broke the cloud layer, Juras witnesses a solitary protoss civilian being killed by the zerg. Only then did he realize the true nature of the zerg, and came to believe they had to be destroyed. He immediately began cooperating, unleashing the mothership's special systems against the zerg.
The Moratun rescued a number of survivors as other empty motherships warped into Aiur's system. Martul's warriors and the survivors were distributed among the ships. One survivor knew a little about the evacuation, which had already been completed. He knew the protoss had fled through a warp gate along with the Dark Templar, but knew nothing else. Juras and Martul determined to take the mothership fleet into space, searching for the protoss.