Stepbro and stepsister engage in sexual activity and bring in a young person for a threesome

A young guy and his stepsister are chilling in the dorm when the topic of sex comes up. As they're discussing, a cute girl happens to walk by, and the stepsister invites her in for a chat. The guy, seeing an opportunity for a threesome, decides to play along. After some small talk, the stepsister and the girl start getting it on, with the guy joining in. The stepsister, being a bit of a wild one, enjoys the extra company and the guy is more than happy to oblige. The girl, not entirely comfortable with the situation, tries her best to keep up. The guy, being a skilled lover, manages to get her into the mix, resulting in a steamy threesome. This is a taboo scenario that many would shy away from, but these characters are all about pushing the boundaries.