Slime Girl Sister
Copyright© 2025 by Aramis
Chapter 1
Science Fiction Sex Story: Chapter 1 - The second part to the Slime Girl trilogy. Kenny meets Lilah, Cindy's sister, and finds out that she's even more of a handful than Cindy!
Caution: This Science Fiction Sex Story contains strong sexual content, including Ma/Fa Consensual Heterosexual Fiction Science Fiction Cream Pie Oral Sex
(Author’s note: this is a work of fiction. Any resemblance to any person(s) living or dead is purely coincidental. All characters depicted in sexual situations in this story are at least 16 years of age. This work is copyrighted and may not be distributed in any way by any person(s) without the expressed written consent of the author. This story is a continuation of “Slime Girl Lover,” so if you haven’t read that one you might want to do so before reading this one.)
The two days before Cindy’s sister, Lilah, arrived went by quickly, with Cindy pumping as much cum out of Kenny as she possibly could. If he didn’t know better he’d have thought that she was trying to drain him dry to deprive her sister of it, but he knew better. Slime girls were extremely loving to family members, and she was not only proud to be able to share her human lover with her sister but was looking forward to it as well. She was just excited about it all, and this was her way of showing it.
All Kenny knew was that he’d never cum so much in his entire life, all thanks to the special chemical that Cindy’s body emitted when she was aroused – which was most of the time, typical of slime girls. He only wondered if her sister was going to be the same as Cindy was.
He had no idea what he was in for.
When there was a knock on the door early Saturday morning Cindy jumped up from the couch where she had been cuddling with Kenny, almost knocking over the coffee table in her rush to answer the door. A few moments later he heard the door opening followed by the squeals of delight from both Cindy and Lilah. They stood in the doorway talking and squealing with delight for a few moments, then Cindy brought Lilah into the living room. They stopped in the entrance, both of them with big smiles on their faces. Kenny was surprised to see that Lilah was green instead of blue like Cindy; he also couldn’t help but notice that Lilah was dressed almost identically to Cindy, both of them wearing shorts that fit them like a second skin and tank tops that were barely able to contain their huge breasts. And, unbelievably, Lilah’s breasts were even bigger than Cindy’s.
“Kenny, this is my sister, Lilah! Lilah, this is Kenny, my boyfriend!” Cindy said, grinning from ear to ear, her yellow eyes sparkling.
“Hello, Kenny! It’s so good to meet you at last!” Lilah said, walking over to where Kenny sat on the couch, her mammoth breasts jiggling and swaying inside her tank top. Kenny stood up as she approached, taking her hand when she offered it. She was also a little taller than Cindy, standing a little more than seven feet tall, with Kenny feeling a little overwhelmed as he looked up at her.
“My pleasure, I’m sure!” Kenny replied, returning her smile.
“It will be both of our pleasures, actually,” Lilah said, grinning from ear to ear. “Cindy has told me all about you and your very large penis, how good you are in bed, and I can’t wait to find out for myself!” she said in typical slime girl bluntness, looking him in the eyes as she spoke. Then she looked over at Cindy as she continued, still holding onto Kenny’s hand.
“He’s just as cute and sexy as you said he was!” she said, still grinning.
“Just wait until you see his large penis!” Cindy replied, grinning as well.
“I can’t wait, and I can’t wait to suck on it, too! So when can I see and then suck on your large penis, Kenny?” Lilah asked, turning to look back down at him again.
“Whenever you want, I guess,” he replied, feeling his cock beginning to stir in his pants.
“How about now?” Lilah asked, taking him by surprise. “Is it okay if I suck his penis right here, Cindy?” she asked her sister, turning to look at her while still holding onto Kenny’s hand as if to prevent him from running away.
“Is it okay if I watch?” Cindy asked, much to Kenny’s surprise.
“Sure!” Lilah replied, turning to look back at Kenny. “It’s okay if she watches, isn’t it, Kenny?” she asked, her voice soft and seductive as she looked down at him, still holding onto his hand.
“Sure, why not?” Kenny replied, smiling as he shrugged his shoulders.
“Great! So let’s get to it!” Lilah said, dropping down to her knees in front of him. She was so tall that even on her knees her head was level with his stomach, so she sat back on her haunches to get a better look as she eagerly reached for his pants to unfasten them. She had his pants open and the fly down in seconds, immediately yanking his pants down and revealing his cock to her. He was going ‘commando’ as usual, and Lilah squealed with delight when she saw the long tube of his semi-erect cock hanging down in front of him.
“You weren’t kidding, Cindy, he has a beautiful penis! And so big!” she said, her eyes sparkling and a big grin on her face as she looked at his cock, reaching out and wrapping her soft, slippery fingers around his semi-erect shaft, holding it up and then gripping it firmly. “I can’t wait to see it when it’s fully erect!” she said, slowly pumping it in her hand. Her fist slid easily up and down on his shaft thanks to the natural lubricating effect of the slime that she was made of. Kenny felt his cock growing bigger, thicker, and harder by the moment, with Lilah wrapping her other hand around his shaft as well. She gripped his quickly hardening cock tightly with both fists as she slid them up and down, his cock sliding smoothly through her naturally slippery hands, never taking her eyes off of the bulbous head of his cock as it protruded from the top of her green fist.
“MMMMMMM, I just love feeling a human’s penis growing hard in my hands!” Lilah said, looking up at him and smiling as she spoke. “Almost as much as I love feeling it growing bigger and harder in my mouth – but we have plenty of time for that later, right, Cindy?” she asked, glancing over at her sister who was watching with rapt attention.
“Right, Lilah,” Cindy replied, a little breathlessly as she watched her slime sister pumping her boyfriend’s hard cock with both hands. Lilah turned her attention back to Kenny’s cock, gripping it tightly and sliding her fists up and down a little faster. The feeling of Lilah’s naturally slippery hands gripping his hard cock tightly as she slid them up and down the shaft was nothing short of heavenly, and a few moments later she was rewarded with a big drop of precum that appeared at the tip.
“Now that’s what I’m talking about!” Lilah said, looking up at Kenny with a big smile on her face. Then she dropped her mouth down to his cock and stuck out her big blue tongue, licking the drop of precum off of the tip of his cock and swallowing it. She pumped his cock harder, and another big drop of clear liquid appeared at the tip almost immediately.
“Wow, you must really be excited, huh, Kenny?” she said, smiling as she looked up at him. Then she put her full, soft, slippery lips on the head of his cock and sucked the precum out of him, pumping his shaft hard as she did. Kenny could feel the precum being sucked out of him, and after a few moments of this delightful torture she slipped her lips from the tip of his cock and looked up at him, a big smile on her face.
“MMMMMM, tasty!” she said, looking up at Kenny and licking her lips. “Now let’s see if the rest of you tastes as good!”
With that Lilah slid her soft, slippery lips down onto the head of his cock, sliding them over the flared ridge and all the way down his shaft, moving her hands out of the way as she took the entire length of his now rock-hard cock into her mouth. It never ceased to amaze Kenny as he watched Cindy deepthroating his cock with ease as slime girls had no gag reflex, and now to watch her sister swallow his cock just as effortlessly was even more erotic and exciting. Lilah held his cock in her mouth for a moment, looking up at him and winking as she held it in her mouth, her nose touching his abdomen. Then she slowly slid her mouth back up the length of his shaft, sucking harder than any human female ever could. She was sucking so hard it felt like his balls were going to be sucked out through his dick, her cheeks caving in from the intense suction she was applying, and he moaned as Lilah got to the head of his cock. She held it in her mouth for a moment, sucking hard as she swirled her soft, slippery slime tongue over and around it, then pushed her mouth back down onto his cock again. She repeated this routine several times, savoring the taste and the feel of his cock in her mouth while Kenny enjoyed the sensations of her wet, slippery, sucking mouth sliding up and down on his hard cock.
“She’s good, isn’t she, honey?” Cindy asked, watching with rapt attention as her sister sucked her boyfriend’s cock.
“I’ll say!” Kenny gasped, putting his hand on the top of Lilah’s green head as she slid her mouth slowly up and down on his turgid cock, feeling the slick softness of Lilah’s slime head beneath his palm. “She’s just as good as you are!” he said, meaning it.
“She should be; she’s the one who taught me how!” Cindy said, surprising him.
“She did?” Kenny asked, his eyebrows going up in surprise.
“Uh huh, she did,” Cindy said, nodding and smiling.
“Who did you practice on?” Kenny asked, knowing that neither of them would take it wrong as most human women would have.
“One of her boyfriends,” Cindy replied.
“Only his penis wasn’t as big and thick as yours, that’s for sure!” Lilah said, taking her mouth from his cock just long enough to speak before diving back down on it again, sucking just as hard as before.
“Make him cum, Lilah, I want to see him cum in your mouth!” Cindy said, her voice a little breathless as she watched Lilah sucking on Kenny’s cock. The blurry image of Kenny’s cock sliding in and out of Lilah’s mouth excited her, and she was anxious to see Kenny’s cock explode in her mouth and fill it up with his cum.
Lilah nodded in response, and to Kenny’s pleasant surprise she began sucking on his cock even harder. She increased the tempo of her mouth sliding up and down on his cock, reaching up to grab his balls with her hand as she did. She began squeezing and tugging on them as she sucked on his cock, and it wasn’t long before he felt the beginnings of the first of what he was sure was going to be a long string of orgasms, thanks to the chemical Cindy and Lilah’s bodies emitted. And Lilah’s body was producing the chemical steadily now, the room filled with the aroma of strawberries.
“Oh, shit, here it cums!” Kenny groaned, breathing hard and fast as Lilah sucked on his cock. Then he grabbed Lilah’s head in his hands and pulled it towards him as his orgasm hit, moaning loudly as his cock exploded in her mouth. Lilah slapped her hands on the front of his thighs and moaned with pleasure as his cock blasted stream after stream of hot, thick cum into her soft, sucking mouth. Then she reached around and grabbed Kenny’s ass with both big hands, squeezing it hard as she pulled him towards her to shove his cock all the way into her mouth.
“Yes! That’s it, that’s it!” Cindy cried with glee, a big grin on her face and her eyes sparkling as she watched Kenny’s spurting, pulsing cock fill up her sister’s mouth with his cum. Kenny grimaced and groaned loudly as his balls emptied themselves into Lilah’s wet, sucking mouth, his knees shaking. Cindy could see the mass of cum in her sister’s mouth getting bigger with each pump of his cock, watching it travel down to her stomach when Lilah finally swallowed. Lilah held her mouth clamped onto Kenny’s cock, sucking hard as he continued cumming, and when his orgasm finally ended it left him gasping for breath and Lilah with a big glob of cum visible in her stomach. She slipped her mouth from his still-hard cock, releasing his ass from her hands as she sat back on her haunches, looking up at him and grinning.
“Wow, that was great! You came a lot, and your cum tastes really good, Kenny!” she said, licking her lips.
“That was so hot!” Cindy cried, grinning from ear to ear. “You made him cum so good, Lilah!”
“I did, didn’t I?” Lilah said, looking up at Kenny past his still-hard cock, grinning from ear to ear.
“Yeah, you did,” Kenny gasped, returning her smile.
“And that’s just for starters,” Lilah said, getting up from her knees and standing in front of Kenny, her mammoth breasts pressing against his chest. “Now I want to feel that big, hard penis of yours inside my vagina!” she said, putting her hands on Kenny’s chest and pushing him backwards onto the couch. He fell back onto the couch with a slight grunt, his hard cock bouncing in his lap as Lilah quickly stripped out of her shirt and shorts. She immediately climbed onto his lap, one knee on either side of his hips, her huge, heavy breasts pressing against his face as she got into position. She reached down and grabbed his cock with her hand, pointing it up and placing it against her opening, then sat down on it. She moaned as she swallowed up his entire length in one smooth, fluid motion, pushing her ass down onto his lap and squeezing his hard cock inside her with her inner muscles.
“MMMMMMM, that feels good!” she said, grinning down at Kenny. Then she lifted her huge, heavy, slime breasts up and put them on his shoulders, effectively trapping his head between them. Her breasts were so big that his nose barely protruded above them, and he had a feeling that before this was over Lilah was going to encase his head in her breasts, merging them into one like all slime women could do. She put her hands on the back of the couch and pressed her big breasts together, almost swallowing up Kenny’s head as she began riding his cock.
“Oh, my God, that feels so good inside me!” Lilah said, looking down at him and grinning as she slid her tight, wet, slippery pussy up and down on his hard, throbbing cock. She wrapped her arms around her breasts which were around his head and squeezed, pushing them together around his face and covering his nose as she rode him harder and faster.
“MMMPHH!” Kenny cried from in between Lilah’s huge slime breasts as they covered his face and head. They were warm and soft against his skin, slightly slippery, and very heavy. Just as he knew she would Lilah merged her breasts together, encasing his head completely as she rode him.
“Careful, Lilah, don’t smother him!” Cindy cautioned as she watched her slime sister riding her boyfriend’s cock. She could see the blurry image of his cock inside her, the slippery, sucking sounds of Lilah’s pussy sliding up and down on it filling the room. Lilah rode his cock for a little longer, Kenny’s head still encased inside her breasts, and when Kenny finally slapped his hands against her hips Lilah separated her breasts and released his head. Kenny took a big, whooping breath as soon as his mouth and nose were free, making Lilah laugh.
“You okay, Kenny?” she asked, grinning down at him as she continued riding his cock.
“Yeah, I’m good,” he gasped, looking up at her and nodding. “Your sister does that to me all the time so I’m kinda getting used to it!” he said, chuckling.
“Your penis feels so good inside me, so big and hard!” Lilah said, looking down into his eyes as she rode his cock, squeezing it with her pussy. “I can’t wait to feel it shooting inside me as it fills me up with your semen!” she said, her yellow eyes sparkling.
“You keep doing what you’re doing and it won’t be long,” Kenny said, already feeling his balls shifting.
“That’s the idea!” Lilah said, chuckling as she rode him.
Lilah’s pussy was tight, very tight, and very slippery as well. And since it was slime just like the rest of her body she was able to shape and control it at will, and right now she was squeezing it so tightly around his cock that it felt like one big, strong hand was squeezing it. Then she wrapped her arms around her big breasts again, pushing them together as she leaned forward to ride him even harder. She didn’t merge her tits together this time, leaving Kenny’s nose free so he could breathe as she fucked him hard and fast. Kenny put his arms around her, reaching down to grab her ample ass and squeezing it hard as she rode him, his fingers sinking into the soft mass of her ass.
Cindy watched as Lilah rode Kenny’s hard cock, sitting down in the chair across from the couch and leaning forward with her elbows on her knees. She could feel her own arousal getting stronger, and was looking forward to when it was her chance to get Kenny’s cock inside her slime pussy. But right now it was Lilah who had it inside her, and she was very obviously enjoying it, her ass rising and falling quickly as she slid her pussy up and down on the length of Kenny’s cock.
“I’m going to cum all over your penis, Kenny, and I want you to cum with me!” she said, gasping for breath a little as she spoke.
“I can do that,” Kenny replied, his voice muffled by her huge breasts pressed around his head.
“Give it to me, Kenny, give it to me!” Lilah gasped as she rode his cock, squeezing it harder than ever. “I want it all, every last drop of your semen, so give it to me!” she urged, pressing her huge, heavy breasts together against his head and almost smothering him again. Kenny felt his balls shifting again under the intense onslaught of Lilah’s tight pussy squeezing his cock and her huge, heavy slime breasts wrapped around his head, and a few moments later he came again.
“HNNNNGHHHH!” he grunted, grimacing as a second powerful orgasm ripped through him. He squeezed Lilah’s ass hard as his cock exploded inside her, throbbing as it pumped stream after stream of hot, thick cum deep inside her.
“Yes, yes, yes, that’s it, that’s it! Give it to me, give it all to me, fill me up with your sperm!” Lilah cried out in delight, feeling Kenny’s cock pumping and pulsing inside her. She continued riding him as his cock pumped out more and more cum, and Cindy’s mouth fell open as she watched the ball of cum inside her sister grow bigger and bigger as Kenny continued to cum.
“I’m gonna cum, I’m gonna cum! NNGGHHHHH!” she moaned through clenched teeth as her orgasm hit, the waves of pleasure making ripples through her slime body as she continued riding Kenny’s pumping, pulsing cock.
“Oh, my God, Lilah, he’s shooting so much semen inside you! That is so hot!” Cindy said breathlessly, her yellow eyes wide and sparkling as she watched her sister riding Kenny’s cock. Her big nipples were hard as rocks and she could feel her desire building inside her, and she began hoping that Lilah would be finished with him soon so she could take over and drain more cum out of him.
When his orgasm was over and his cock had finally finished pumping inside Lilah’s vise-like pussy Kenny was left gasping for breath – but his cock was still hard as a rock. Lilah had also finished cumming, pausing to sit on his cock for a few moments to catch her breath. From his past experiences with Cindy he knew that Lilah wasn’t finished with him yet. She proved him right by sitting up and grabbing him by the shoulders, then turning him to the side and pushing him down onto the couch on his back, keeping his cock trapped inside her as she did. She immediately leaned forward and mashed her big, heavy breasts into him, one on each side of his face, wrapping her arms around his head and pulling his head into them as she lay on top of him. She began riding his cock hard and fast, her hips rising and falling quickly as she rode his hard cock, squeezing it with her pussy hard as she did. The room was filled with the squishy sounds of Lilah’s slime pussy sliding up and down on his cock, with Cindy watching with rapt attention.
“If I don’t get his penis inside me soon I’m going to lose my mind!” she said, reaching down and rubbing her crotch as she watched her sister fucking her boyfriend hard and fast, the couch shaking beneath them.
“Let me make him cum one more time and then you can have him,” Lilah said, chuckling as she looked over at her sister. Then Kenny said something, but since his head and face were covered by Lilah’s big breasts it came out muffled. Lilah eased her grip on his head and sat up a little to free his face from between her huge tits.
“What was that, sugar?” Lilah said, looking down at him and smiling as she continued riding his cock.
“I said, don’t I get a say in this?” Kenny said, gasping for breath.
“NO!” Lilah and Cindy said at the same time, both of them then laughing. Lilah wrapped her arms around Kenny’s head again and pulled him deeper between her mammoth slime breasts, increasing the pace of her pussy sliding up and down on his cock.
“I’m going to make you cum again now, Kenny, so my sister can have her turn with you!” she said, looking down at him and smiling. She gripped his cock harder with her pussy, milking it along every inch of its length, her hips rising and falling fast as she rode him faster and faster. A few moments later Kenny felt his third orgasm building, and thanks to the chemical in Lilah’s body he knew this one was going to be just as big as the first two.
A few seconds later he was proven right, and he groaned loudly from between Lilah’s huge, heavy breasts as he came again, his cock exploding and pumping another big load of hot cum deep inside her clutching, squeezing pussy. Lilah laughed with glee as she felt his cock pulsing and pumping inside her, loving the feeling. She continued riding his cock hard and fast as his orgasm ran its course, his balls emptying themselves into her pussy. When it was over and the throbbing of his cock had stopped she sat up, keeping his cock inside her as she pulled her mammoth green breasts away from his head and face.
“Holy shit!” Kenny gasped as he took a big breath, his chest heaving as he tried to catch his breath. He lifted his head and looked at Lilah’s stomach, surprised at the size of the blob of his cum that was inside her. He could see it slowly getting smaller as her body absorbed it, the fuzzy outline of his still-hard cock inside her visible through her stomach.
“Now it’s my turn!” Cindy said, jumping up from the chair and quickly stripping out of her shirt and shorts. Lilah reluctantly climbed off of Kenny, releasing his cock from her pussy to slap against his stomach, and Cindy just about threw Lilah across the room as she grabbed her by the shoulder and pulled her out of the way. She quickly climbed on top of Kenny and grabbed his cock, her huge blue breasts swaying as she moved, pointing his cock up at her pussy and then sitting down on it. She took his entire length inside her in one smooth, fluid motion, closing her eyes and moaning with delight as she felt it filling her up, a smile on her face.