While Mustang suspected that was what Vrenille meant, because , of course, it was, hearing the words and the concept spoken so earnestly is a little intimidating. He doesn’t know if it’s his pride, his need for dignity or, perhaps, for control, but he’s intimidated.

He can’t help it.

Yet, he doesn’t pull away. Despite the feeling and his initial reaction, Roy is intrigued. He knows how to submit. Hadn’t the military taught him? Hadn’t Heathcliff taught him? Alright, he’d told himself that the Ishvalan made him do it, but Mustang knows damn well that if he hadn’t wanted it himself, no way would he have been able to force him.

Besides, when Vrenille touches him, he closes his eyes and inhales a shuddery breath. It would... feel good to let someone other than he make all the decisions. He wants to see where this will go. It’s just... this ridiculous paper thing he wears tents his erection, making it, god, too obvious.

Then, Mustang no longer cares. He wets his lower lip, leaning into Vrenille and suppressing the impulse to salute. When he speaks, his baritone is quiet, words meant for just the two men. “My will is yours. Sir.”