Slavery: A series of erotic games (book 04)
"I'm a slave, serving a Mistress on Master's orders. You should be treated with the respect due to an owner of another slave. We're not working now where I'm your boss. I'm serving you."
Rhonda got the strapless and turned it on. She lubed Sean's ass before letting him penetrate Lisa's ass. After he was embedded in her, she shoved into his, driving deep. I set my timer for twenty minutes again. I showed it to Shasta. I don't know if Sean would appreciate a twenty minute ass fucking, but Lisa wouldn't mind one at all.
Shasta nodded and said, "You don't cum before the timer, slave."
"Yes, Mistress," Sean grunted, undergoing what he was giving.