Your sister comes to you with a problem...a guy problem. Her boyfriend rented a cabin in the woods for a romantic weekend getaway and she wants to know, from a guy's perspective, what he expects from her...y'know. Sexually. Your sister, nervously sipping her soda while you prod her to give up more info. You've always thought she was cute - perhaps a bit of a tease - and seeing her squirm, so inexperienced and vulnerable, has you excited.
You tell her that you can show her what a guy expects. That you want to do a hands-on demonstration. Her reluctance is palpable, but she's never been too clever a girl. You can see her mind racing through her doe-like expression, you can tell if you push this and promise her that her boyfriend will love what you teach her, you can have your way.
It doesn't take long before your little sister is unbuttoning her blouse, looking up at you as you advance, pulling her legs over the edge of the couch and standing above her. It doesn't take long before she's begging you not to, asking you to stop as you firmly instruct your sister on the finer points of deepthroating your cock. You're ready to take what you want, even if she fights...
Of course, in the end she's begging for it, just like you knew she would. Just like a well-trained cum slut should