A favor for a favor: step-siblings help each other out

Service for service is a principle that ideally transforms interaction between people into a system of mutual assistance, where everyone gets something in return for their efforts. Boring? Exactly. Laya and Riley decided not to be bored, but to go to a party in the evening and have sex with strangers there. But here's the problem. Their parents ordered the girls' stepbrothers to watch them and report back. What to do? Maybe offer them sexual favors in exchange for their silence?