The high pitched whine that comes up out of Nero's throat is Cid's reward, as he holds himself stil and tries not to turn this into a very active- face fucking. If he does, he will get noisy, he will announce to the Ironworks they are fucking, and so many people will be upset (not the least of which will be Garlond himself.)

But he does have to take his fist out of his mouth to warn: "G--Garlond, G-- gonna--! I'm almost there."

Because he would be shortly after, biting red marks into his fist once more as starbursts light up his eyelids.