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Koida 'Vadam was a Sangheili noble of the House of 'Vadam, serving as one of the elders of Vadam. He was not a warrior and did not enlist with the military service, and so was not permitted to add the "-ee" suffix to his name.
In 2535, Koida voted in favor of making Shipmaster Thel 'Vadamee the kaidon of Vadam keep. However, he later regretted his decision, fearing that Thel was no longer a strong warrior and had weakened, as Thel had spent the past couple years fighting humans and "lesser" races of the Covenant rather than Sangheili. Koida sent a trio of assassins to kill Thel in his bed chambers, though the newly elected kaidon succeeded in killing all three of them.
Sequentially, Thel confronted the state's elders and claimed that he had interrogated one of the assassins. Upon seeing Koida's reaction, Thel correctly deduced that it was him who sent the assassins. Thel angrily demanded to know why Koida had not voted against him or challenged him personally, threatening to remove Koida's lineage from Vadam. Koida then attempted to kill Thel himself, only to be decapitated by the kaidon with an energy sword. As Koida had shown courage in his last moments, Thel gave Koida's lineage the chance to leave immediately or be killed.
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