You walk in on your younger stepsister as you're visiting home, and she is busy texting some boy. You take her phone to joke with her, and she suddenly gets very defensive. You see she has been sexting with this guy and he has asked her for a blowjob tonight on their date. As a protective older stepbrother, you ask questions, prying into her personal life. She confesses that she has never done anything, ever. She hasn't even seen a penis. It's embarrasing, but she has no idea what to do. She asks for your advice, and you suggest something way more physical. You tell your stepsister she can suck you if she wanted to learn, just for educational purposes... She likes the idea, but she's worried about crossing certain lines, like full sex. She takes your cock, sucking it for awhile as you teach her how to do it, preparing her for her date tonight. You want her to do well and she is doing fantastic with you. Suddenly, something comes over you as you get close. You lean forward, pushing her down to the bed, and you cross the taboo line with your stepsister you two promised not to pass. You start to enter her, and she takes it slowly, wincing at her first cock, her stepbrother. At least it's with someone she loves. Someone who loves her. You fuck her, filling your stepsister's virgin pussy with your cock, fucking her until she cums. She leans up, you kiss her, and she tells you to pull out when you get close. You nod, but she feels herself filling with pleasure more as you pump and pump, and when you're about to erupt, she says not to stop, holding you inside of her, surprised as you fill her pussy up with cum... She shockingly takes it, worried about pregnancy, but filled with a sexual glow that she's never felt before...