It's not like either of his princes haven't seen Piotr naked before, but he's never invited them to look before. But he's also never been betrothed to a prince's daughter before. He stands at parade rest and allows Xav to examine him. Yuri, his feet up in the corner, calls out orders for Piotr to display himself, but he's laughing, so he doesn't mean them. Xav, though, is determined to keep staring until Piotr gives him the satisfaction of being embarrassed. Xav's inspecting him like a cheap horse, looking for any reason to defy his Emperor and forbid this marriage. And if Xav could somehow find a second dick on Piotr, perhaps Dorca would let him.
Xav mutters something slanderous about Piotr's scars hiding mutation-destroying surgery and Piotr's head snaps up. A mistake. "Get too close to Vashnoi?" Xav taunts him and Piotr forces himself to remain still and obedient. He won't give Xav the pleasure. He'll pass inspection. He'll marry Xav's daughter. And Xav won't stop it. Xav can prod him all he wants; Piotr's passed worst tests. And he has an ally here.
"Ignore him, cousin," Yuri says, standing up. He embraces Piotr. "Congratulations, you're marrying the Princess."