Ask her what fantasy she was planning on granting you

You answer your sister quietly, “I’m sorry Abs, I’m just nervous. If anyone found out about us, it wouldn't be great.” Then you catch on that she’s offering to fulfill a fantasy. You ask, “What fantasy are you talking about?” You’ve got plenty of fantasies, but now they all seem much less interesting than reality with Abbie.

“Oh, just name any you want, and I’ll go along with it. But the one I haven’t been able to get out of my mind, ever since you mentioned it, is your fantasy of having a loyal, obedient fucktoy ****,” Abbie murmurs low. “Just with me as the ****, instead of that girl Tracey.” Her hand moves to his crotch, and her warm, delicate fingers wrap around your hard shaft through your boxers.

“I love the idea of being controlled, owned,” Abbie continues. Her fingers trace slowly up and down the length of your cock over the thin cotton. “I’ve played at bottoming and subbing to guys before. You’re the only man I’ve ever felt I could trust enough to be my real Master.” She slides her fingers into the fly of your boxer shorts and pulls you cock out to stroke it skin to skin.

You’re excited by the feel of your sister’s hand on your cock, and nearly overwhelmed by her suggestion that you could be her Master. Your cock throbs and leaks precum. Abbie rubs her palm over the tip, smearing the fluid around to lubricate her hand. Her strokes and twists over the head make slick, wet noises.

“Mmmmmm…” you moan low. “That sounds incredibly hot. Tomorrow afternoon, before Mom gets home, let’s do that. You can play ****-girl, and I’ll be the Master.” You’re grinning so wide, your cheeks almost hurt.

Abbie moves her face closer and gives you a soft, but lingering kiss. “I think you don’t understand what I’m saying,” she whispers, “I don’t mean roleplaying as Master and ****. Not just commanding me to do what you desire when we fuck. I mean, make me your **** — always. Set the rules I live by. Control my life.” Her hand keeps slowly pumping your shaft the whole time she speaks.

Your breath comes fast and shallow. “Holy crap, Abs. That’s a hell of a fantasy. I never imagined anything like that coming true… It’s a lot. Are you sure that’s what you want?” you ask. Your cock strains and your hips arched forward, thrusting into your sister’s softly stroking hand.

“If it’s truly what you want,” Abbie answers, “it would be a dream for me. But I don’t want to pressure you. Anything we do has to work for you. If you want us to be equals, I’ll be overjoyed just to be with you. If you want me to be a demanding dominatrix, I’ll have to do some research on it,” she giggled, “but I’d be happy to do it for you. If you want me as your ****, I’ll be ecstatic. As long as I’m making you happy, that’s what I want.”

You can’t hold back any longer. You let out a strangled grunt between clenched teeth and shoot spurt after spurt of thick cum into your sister’s hand. It drips through her fingers onto your bedsheet.