[Ren's doing really damn well, considering how little control he has of the situation. Those subtle movements of his head and tongue clearly communicate how far Iwai can push before he might actually hurt Ren, and that gives Iwai the confidence to thrust into his mouth with more force because he knows Ren won't try to overshoot his abilities. Even if he has to keep his thrusts shallow to avoid hitting Ren's throat, Iwai can still show him how it feels to have his face vigorously and enthusiastically fucked by a grown man.

And god, it feels incredible. Ren obviously knows there's more to his side of the job than just opening wide enough and enduring the penetration like some people do, and the flex and release of his cheeks and tongue around Iwai's length have his head spinning in no time.]

Fuck, yeah... [The gravely rumble of his voice has dropped even deeper, low and thick with pleasure.] You like this, huh? I bet I could cum down your throat and send you home achin' for it and you'd still come back for another round.

[He's not going to, but the temptation is definitely there. A sizable part of him wants to get right to the edge like this and then pull out and come all over Ren's pretty face and mussed hair and those big, stupid glasses, but he's not going to. He's just put the fear into Ren's head to see if it changes his behavior at all.]