Percy backs off when he realizes Essek is getting up. The question momentarily distracts him, and he realizes that the wizard is offering to create a surface somehow. That forces Percival to think about logistics when all he wants is to bury his cock, which is only fair, since Essek is going to attempt to cast a spell when all he wants is to be bent over.

He huffs through his nose and looks at the wall that hides them from the entrance. The wolf approaches it and braces his forepaws against it to give Essek an idea of just where his hips might be when he isn't trying to fuck a partner who is quite low to the ground.

Your hips should be against it when you're bent over, he rumbles as he pushes away from the wall. Not quite as tall as his desk which, he recalls, forces Essek up onto the balls of his feet when he's bent over it.

Wide enough to brace yourself. Wide enough for me to lean on it.

That also saves them the concern of Essek taking his weight at all.