Slavery: A series of erotic games (book 04)
"He doesn't have to imagine it, Mistress Shasta. Rhonda can put on a strap on and fuck his ass while he fucks Lisa's."
"Okay, but who lick me if Rhonda busy?"
"That would be me, Mistress Shasta," I said. "Master wanted Lisa and I to pleasure you. Lisa give Rhonda the camera so she can take pictures for Master."
"Then I can see if Rhonda really is the best?" She mused.
"Yes, Mistress Shasta."
"Why you call me Mistress all of a sudden?" Shasta asked.
"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."