You felt like you had crossed a point of no return with your sister. Molly had shoved your face in between your boobs (which you greatly enjoyed) and then commanded you to jack off in her presence. Without a second thought, you had obeyed her. Now, your mom was growing and who knew if she would develop the same dominant personality tendencies that had recently surfaced in Molly. 

You felt dirty inside. What had your life become? Being turned on by thoughts of your own family, had you no shame? On one hand, you could try to resist, which you knew deep down would be a feeble attempt at slowing the inevitable. On the other hand, you could give in. Give in to your desires and your most depraved cravings. 

You climbed into the shower and as the water washed over you, your thoughts swirled. Your sister was a  nymphomaniac practically and soon enough, your mom Angela would be too. Molly was about 6'5'' with F cup breasts and Angela wasn't far behind at 6'0'' and DDs. Molly's friends had also grown into human sex dolls. The whole situation seemed crazy. 

As you shampooed, you heard the bathroom door open, but couldn't open your eyes.

"I'm in here!"

There was no response. 

"Hello?"

Again, no response. The curtain was pulled back and you felt the cold air on your skin. Something soft touched your upper back, making you flinch. Two things, actually. Quick as you could, you rinsed the soap out of your eyes and turned around, half-knowing what you would find. You gazed up at the bright eyes of your 'baby' sister, Molly. She stood totally naked, her nipples erect and her pussy neatly shaven. This was the first time you'd seen her in the nude. She had a beautiful womanhood, better than you could have imagined, and it complemented her curvaceous hips. The hourglass figure was completed by her massive breasts which you'd been personally acquainted with not long before. 

For the first few seconds neither of you spoke a word. You didn't have to. 

"Molly..."

"I want this, Tim. Let me have it."

With that, she bent down and kissed you. You weren't sure what to expect, but it wasn't that. She pinned you against the shower wall, kissing you. She held your neck with one hand and your cock with the other. The water trickled down Molly's body and then yours. You didn't know how long, you made out with your sister, only that it felt like heaven. 

After a minute, she pulled back.

"Well? What do you think?"

"I think you're the sexiest girl I've ever met. I need you, Molly."

She smiled. "Good answer, you know how to make me happy. Why don't you say hello to your friends?"

She shushed her wet tits in your face and jiggled them around. You motorboated them, which made her laugh. 

"You love these, don't you? I knew you had a thing for girls with big tits. Ever since I saw your search history," she said. You blushed, thinking of all the dirty shit you'd jacked off to over the years.

"Let's see how well you like my fat ass, Timmy."

She turned around and your eyes grew wide, seeing just how big her butt had grown. You'd seen it, sure, but only contained in her short shorts or leggings. Here, standing before you, it took your breath away. Every slight movement she made caused it to ripple and jiggle. The skin was smooth, without a trace of cellulite or wrinkles. You were so busy staring at it, you didn't notice Molly backing it up, closer and closer to you, until your dick was wedged between her ass cheeks. 

"Mmmm, that feels good," you said, grinding your dick on her. 

She moaned a little and then said, "I want to try something else. Get on the floor."

"W-what?"

"Get. On. The. Floor. Now."

"O- ok, Molly."

You sat down on the floor, looking up at her. From here, she truly looked like a giant. You couldn't see her face beyond her tits and her ass hung out, blocking her backside too. She peered down at you, with an almost evil look.

"Close your eyes, big brother."

You closed them. What was she planning on doing?

You smelt something funny and then felt a huge weight on your face. Instinctively, you opened your eyes, but it was completely dark. The powerful smell overwhelmed you and you realized that Molly was sitting on your face! Her huge, wet ass was smothering your face and she hadn't even given a warning! You had just enough space to breath and felt her beginning to grind on you. 

"Lick me! Use your tongue! Yesss.... that's it! Ooohh oohhh yes yes, FUCK YES!!"

She moaned, grinding harder and harder, faster and faster. Her hips bucked with each stroke of your tongue. In that moment, you felt completely degraded, but so turned on by licking your sister's ass and pussy. 

Molly's intensity of grinding rose to a crescendo and she practically screamed as she had a violent orgasm. You felt her already wet crotch get even more wet. After she'd cum, she didn't get off of your face. You were still being crushed by her huge ass and forced to smell everything that came with it. 

"I think I like having you down there. You certainly knew your way around my pussy... if only there was a way to have you there more often. Then you'd be like my little secret, giving me head throughout the day....."

You didn't like the sound of that, though it was intriguing to be having sex with Molly.

"Anyways, I think it's time for me to hit the hay," said Molly. "Why don't you finish cleaning up. We're going to be spending a lot more time together from now on hehe."