From Halopedia, the Halo wiki
Remarus was an old warrior by the time Hekabe killed him. He had been leading the clan on raiding parties against Sangheili and embroiling it in disputes with other Jiralhanae packs, and Hekabe believed these actions would eventually spell the end of them. In order to prevent any further decisions he thought were putting the clan in peril, he snuck up on his great-uncle from the shadows and slit his throat. Many were surprised by this action, as it was widely believed that Vikus would eventually be the one to seize power from Remarus.
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