My stepsister came home for the holidays and wanted to fuck, asking me to keep it secret

So my stepsister came home for the holidays, and honestly, the step fantasy and stepsister vibe was thick in the air from the second she walked in, but I wasn’t expecting her to flat-out ask me to keep a secret fuck between us, and the way she said it, all casual and low-voiced while everyone else was in the kitchen, made my heart race in a way that felt both wrong and incredibly right, and then she just gave me that look, the one that said she was dead serious, so later that night when the house went quiet, I found her waiting in my room, wearing this tiny tank top and nothing else underneath, and she didn’t waste any time, she just pushed me onto the bed and climbed on top of me, her blonde hair falling around her face as she leaned down to kiss me, and I could feel the heat radiating off her skin as she whispered that we had to be silent, which made every single sound feel ten times louder, the creak of the bed, the soft gasp she let out when I grabbed her hips, the way she bit her lip to muffle a moan when I flipped her over, and the whole time I was hyper-aware of the fact that my parents were just down the hall, but that only made it hotter, feeling her amateur moves mixing with my own, her body soft and eager against mine as we found a rhythm, and I remember tracing my fingers down her spine while she arched her back, and she was so wet and ready for me, and the secrecy made it feel like we were getting away with something huge, her legs wrapped tight around me as we moved together in the dark, trying to stay quiet but failing a little bit, and when we finally finished, both of us breathless and slick with sweat, she just smiled, kissed my cheek, and told me to act normal tomorrow, like nothing happened.