"I'm gonna let you fuck my ass"

You look at Sarah in shock. "Are you sure?" You ask.

Sarah nods. "It's only fair, after all, I got to fuck you. And you already lubed up my hole. Besides, I can tell you from experience, it feels amazing." She giggles. You can't believe this is happening. "Don't be such a wimp, come over here and fuck my ass" Sarah teases.

You stroke your cock a few times and slowly put it up against her ass, sliding up and down her crack a little before settling in the little dimple of her asshole. It occurs to you that you've never seen a woman from this angle before, and you notice her puss is closer than you thought to her asshole. For a brief moment, you entertain the notion of pushing into her pussy instead, but quickly shake your head, banishing the thought. You start to push the head up to your little sister's hole, but pause one last time. "Are you sure about this?" You ask her.

"Does this answer your question?" Sarah asks, and she pushes herself towards you, fully engulfing your cock into her, virgin asshole.

She screams in pain, but you're in a completely different mental state. Never before have you felt this much pleasure. Your sister is so tight, you're afraid you'll cum right now. Sarah quietly sniffles and says, "Alright, the pain has passed, I think. Go to town, Dougy." You don't wait a second longer, and slowly pull your cock out before ramming it right back into her tight ass. You repeat this motion, slowly pulling in and then unceremoniously pushing back in until she's fully accustomed to it, then start picking up the speed.

She screams and moans in pleasure, and, not wanting to wake anyone up and also wanting to feel even close to her, you kiss Sarah deeply, pushing your tongue into her mouth. Her screams and moans cut off abruptly, and she kisses you back with a passion. Your tongues dance as you pound her ass, sending waves of immense pleasure washing over both of you. You grab her gigantic cock and start stroking it, matching the pace you're fucking her with. She moans into your mouth, and you feel her cock twitch in excitement. With every thrust, her body is pushed forward, nearly breaking your kiss. On the return, she pushes back into you, as if trying to prevent your cock from leaving her ass.

She moans uncontrollably into your mouth as you kiss, and briefly breaks breaks away to say, between moans and gasps for air, "Doug, oh Doug! Please... don't... I'm... I'm..." Completely unable to finish her sentence, you can tell she's fuck drunk, and probably lacks the capacity to form a proper sentence, try as she might. You feel her asshole start to spasm as she cums violently on your dick for the second time that morning. Her orgasm is so intense, she blacks out from overstimulation.

You can tell you won't last much longer, either, and with one final pump, you plunge your dick as far into your sister as it will go, wrapping your arms around her chest and pushing yourself down to the bed on top of her. Your cock explodes cum deep in her ass, your orgasm lasting longer than ever before. Completely spent, you collapse on top of your baby sister, unable to do anything other than breathe heavily and bask in the sensations of her body against yours.