Slavery: A series of erotic games (Book 03)
"Slaves essentially, or it could be other Masters or Mistresses with his permission, but generally, only those people Master himself can fuck. If he has sex with a non-slave, we consider it to be a violation of our wedding vows as we don't consider ourselves to have an open marriage where we can fuck anyone we want. To have sex with other slaves is not. After all, through me, he's fucking three slaves, which is not a part of our wedding vows. We had to make adjustments to our thinking to allow sex with others."
"So you've had sex with other Masters?" Cindy asked.
"We did at the beginning," Lisa said. "In order to continue our slavery, we surrendered our right to fuck other Masters. Essential