You both are taking a Shower

"Well, I was going to take a shower so why don't we both hop in together." You say.

"Okay,"

You bend over as you pull back the curtain to turn on the shower and suddenly feel two small hands grab your ass cheeks. Didn't take long for her to get bold, did it? you think. But then again, you can still taste her cum in your mouth and surmise that in her mind you've both already broken past that kind of intimacy barrier. She is right, there's no telling where your relationship is going to go now. You're still horny from sucking her off and decide to let her do as she pleases.

Now that the shower is warm enough you both enter and wash up quickly before you find yourself bent over again with your younger sister feeling you up. She hugs you from behind, sticking her hard cock between your slippery thighs and running her hands along your hips. You're not used to this kind of attention and a part of you doesn't want to admit it but you really want her to fuck you. You stay still allowing her hands to continue roaming. This is her first time ever with a boy and she is making the most of it, she delves her hands between your cheeks going up and down letting her fingers linger a little on your pucker which makes you shiver. She has you in the palm of her hand, literally, and she knows it.

"Let's finish up our shower and continue this on your bed." You say.

"Really?! Alright!" She exclaims. "I'm finally going to find out what it feels like to fuck a boy." She then jumps out of the shower, dries off and runs to her room wearing nothing.

You can't help but laugh with her as her excitement is infectious. You dry off as well and follow her example of walking naked to her bedroom to find her sitting on her bed beaming at you. She and her cock bounce up and down happily when she sees you enter. After getting onto the bed next to her she hurriedly pushes you onto your stomach and you spread your legs for her. She is clearly ready to go as you feel her maneuver between your legs and she lets her cock land heavily on your cheeks which leaves a wet spot of precum on you. The sheer weight of her cock makes you a bit nervous but every boy tries to prepare for this day with a dildo or two. You're a bit shocked at how eagerly you're putting out for her but after she convinced you to suck her earlier and then rubbed her cock on you in the shower your inhibitions have gone out the window. You enjoyed both of those things way too much to stop going now, besides, you never make the best decisions when your dick is hard and you're horny out of your mind.

"Go slow, okay?" You ask her.

"I'll try..." She replies as she rubs the soft mushroom head of her cock between the globes of your ass which become slippery as she goes on. Having only experience with your own cock you're blown away by how much precum girls produce. It excites you to be honest.

Sarah presses herself against your lubed hole and starts rhythmically pushing back and forth letting it relax and envelop the head of her cock. Once her head enters you she pulls it back before entering you again allowing her precum to lube the length of her cock. Before you know it, the entirety of her 10" shaft has slid inside and you can feel her huge balls resting on you. Sarah is now lying on your back shuddering in pleasure. The way she moans and grasps at your body with her hands makes it seem like she is totally lost in the moment. She has only one thing on her mind now, getting as much enjoyment as possible out of her older brother's ass.

"Enjoying yourself, sis?" You ask, drawing her out of her sexually induced stupor.

"Oh my god, yes! This feels even better than I imagined. You feel so good!" She accentuates this last statement by rocking her hips a little bit and flexing her cock inside you. It makes you happy that you can give her this much pleasure and you make a reply of your own by contracting your ass around her length which in turn causes her to involuntarily flex her cock. You like to imagine the additional precum that she deposits inside of you during these actions. Your own cock is hard and pressed into the mattress and gets even harder at the thought of the cum that will soon be pumped into your body. Despite some pain during the initial penetration the rest has felt incredible and you think you're definitely hooked on the feeling of girlcock sliding into you. Your ass feels hypersensitive and you can feel the subtle texture of her cock as it has become buried in you. The warm, full feeling leaves you wanting more. You expect that Sarah will be demanding a lot more of your ass in the future and you actually find yourself looking forward to it.

Your wish is granted as Sarah slowly pulls out of you before driving in again at the same speed. Your prostate feels swollen and the friction against it makes it throb with pleasure. Sarah begins thrusting faster, smacking her hips against your plump ass and holding onto you more tightly. She grunts more into your ear as she lies on top of you enjoying the feelings your ass is giving her.

"Oh Doug, this is amazing!" She says.

Over the next 10 minutes she varies the speed of her stroking to savor the sensation of your slick ass sliding over her thick member and you're surprised that she has the self-control to not just pound you before cumming quickly. She does eventually reach her tipping point and you can almost feel the way her cock swells inside you as she tries to thrust into you as far as possible. Deep in your intestines she shoots her viscous, white girlcum, her cockhead is so large and her expulsions so massive that you can feel her cum filling you up and actually expanding into the space beyond her cock instead of coming out of you. Unbelievably, you feel her cock continue to throb strongly inside you for what seems like whole minutes. Each pulse of her member shoots another blast of cum further into you. The warmth inside begins to build and your sister is actually causing you to become swollen with her discharges.

Through out all of this your prostate glows with pleasure which builds and builds into an orgasm of your own, sending your cum onto your stomach and leaving a wet spot underneath you. It is by far the best orgasm of your life. There is something about the fullness in your ass and the pressure on your prostate that changes your orgasm into something amazing. You can't believe that you came hands free from just getting fucked by your sister's thick cock and on top of that, it was better than your normal orgasms. You no longer wonder why many of your classmates at school have become cum dumpsters for their sisters, you're addicted to this feeling now. You might even offer your ass to Crystal when she comes home.

Sarah, for her part has been shuddering on your back as her orgasm begins to wain and her cock softens inside you. She eventually pulls herself out of your slick hole causing only some of her cum to drip out of you, the rest remains inside on account of how thick it is and the depth at which she placed it.