That... sounds like voidsent worshipers to him, but he lets Peter continue. Sacrificed... he knows that sacrifices of living people is sometimes a thing, though more often it's dead bodies that are inhabited by the voidsent if it's not a statue or something similar.

"I'm so sorry, Peter." He reaches up and puts a hand on the back of the other's head, stroking his hair gently, mindful of his slight claws. "That's awful. That's awful, and I can't imagine how horrible it would be. You didn't deserve that. You deserve so much more."

He moves to carefully give the other a hug. "You weren't given a choice. That's not fair in the slightest. You're very strong, for having survived like that for.. however long it's been."