Zorael looks thoughtful after the rebuttal by his fellow Astartes on the topic of bravery. Though he had the memories of his predecessors to draw upon, their experiences were cautionary tales. After all, they were all dead now. He would learn from their mistakes, but there were plenty of other mistakes he could make himself. Each lesson from the surviving veterans were immensely valuable; they could literally be the difference between his life and death.
The entrance of the primarch makes Zorael almost gasp. Horus Lupercal, his own father Sanguinius' best friend, in the flesh. A true hero, and worthy of immense respect. Of all the people in the universe, only the Emperor and Sanguinius himself stands above him, in Zorael's opinion.
"We are extremely honored to be chosen for this mission," he speaks with sincerity, "Your trust in us is not misplaced. I will do my outmost to ensure the survival of my brethren, and, if the worst should come to pass, make sure that their gene-seeds are preserved."
The grim task of harvesting the gene-seed is something he exclusively can accomplish, but it will hopefully not be necessary. In fact, he'll do his outmost to ensure that won't not happen.