My life changed completely when I got a new stepsister. She's tomboyish and a bit cheeky, but her voluptuous body somehow turns me on. Seeing her enjoying sex alone with her college boyfriend makes me honestly furious. The way she insults me, saying things like "Ew, you're gross, big bro," pushes me over the edge. I can't tolerate her attitude anymore. One day, I discover her secret and use it to blackmail her, calling her out at night to finally make her "be nice" to me.