“Have a good weekend sweetheart, call us if you need anything!” shouted Andrew’s mom as she walked out to her car, her husband already at the wheel and ready to get going. Andrew, a 14 year old gray mouse with a black spot over his left eye, waved to his parents as they left for their weekend trip to his uncle’s cabin. Once he saw the car turn the corner around the street, he closed the front door behind him, letting out a sigh.
“Well, I thought this would be a nice weekend, but I have to take care of Claire this whole weekend.” He whined to himself, walking into the living room to see his sister. Little Claire, his 4 year old sister, was quietly playing with her dolls on the couch. She had a lighter gray coat of fur compared to him, but they had the same green color of eyes. Even though he's seen it plenty of times now, he couldn’t help but blush as he saw her sitting there in her extra puffy diaper and kids t shirt with characters from her favorite show. The reason her diaper was so big, was due to her being quite bottom heavy. Just like he was packing quite a prominent bulge in his own shorts, the family had hyper genes that they all shared. His father had an enormous bulge that went down to his knees, and his mother had boobs as big as beach balls, with a butt to match.
Claire inherited a large rump at an early age, and it was easily seen through her diaper. Andrew didn’t know why his sister was still in diapers though, he vaguely remembers that he was potty trained at that age, but she knew how to change herself so, he didn’t worry about it too much. He walked over to her and smiled softly, the little mouse sitting on her own basketball sized cheeks.
“Hey sis, mom and dad just left, so it’s just us for the weekend. You gotta listen to what I say, okay? “ he said, trying to ensure that he had authority so she wouldn’t be all bratty the whole time.
Claire perked up and smiled back up at him, nodding happily “okay big bro! Can I have juice? I’m thirsty. “
“I guess so, let me get you some” the brother mouse pets his sister on the head and heads to the kitchen, grabbing a cup that came with a lid and straw and brings it over to the fridge. He takes out a jug of apple juice and pours it into the cup nearly to the top, before putting the lid on and brings it back to his sister.
“Here you go sis” he says as he hands the cup full of juice to her. Claire perks up and squeaks while she accepts the cup. “Yay! Thanks Andrew, you’re the best!” she exclaims and quickly starts slurping it down. While she drank her juice, Andrew grabbed the TV remote and turned on the local cartoon channel. Luckily, they both enjoyed the same cartoons, for the most part anyways. It only took about thirty seconds, but as soon as he sat down on the couch, Claire lifted up the cup to him, showing that it was fully empty.
“Andrew, can I have some more? I’m still thirsty!” she smiled innocently. Andrew looked at the cup a little surprised, not realizing just how quickly she could drink a full cup of juice. “Oh uh, okay sis. Be right back.” He takes the cup and goes back to the kitchen, refilling it with more juice and brings it back to her. She squeaks happily again and starts slurping away at it a second time. The mouse boy sat back down on the couch next to her, watching only a minute of the current cartoon that was playing, before Claire let’s out a satisfied sigh and holds out the cup once again.
“Andrewwwww, one more please? I’m still thirsty!” she asked while gently kicking her legs, making her puffy diaper crinkle a little under her large booty. Andrew raises an eyebrow as she requests juice for a third time in the past few minutes. “Um, do you always drink this much juice?” he asks a little flabbergasted, not realizing he never paid attention to what the little mouse girl drank or ate.
“Mhmm! Mommy always gets me lots of juice, it’s so yummy!” she nods and bounces on her butt, trying to act cute for him. He just rolls his eyes, thinking it’s better to not argue with her, and take the cup into the kitchen again, filling up that cup for a third time. That big jug of apple juice was already halfway empty, but thankfully, his parents stocked the fridge and cupboards with lots of drinks and food for the siblings before they left. Andrew comes back to the living room and plants his rear down onto the couch before handing her the cup. She takes it with a giddy squeak and immediately starts slurping it up, and this time, Andrew actually watched as she drank that juice so quickly. He couldn’t believe how fast she drank that liquid, downing the entire cup in thirty seconds. She sighs happily and sets the cup down on the end table next to the couch, patting her belly with a satisfied look on her face. The mouse boy couldn’t help but blush, seeing her little belly be slightly swollen with all that juice she just drank. How could such a small mouse hold that much liquid? He shook his head and tried to focus on the cartoon that was playing, Claire doing the same now.
About an hour went by, the two of them watching cartoons together, before Claire started to get a little antsy, wiggling softly in her spot. Andrew didn’t notice at first, fully engrossed in the show. The little mouse girl had a little internal debate whether to say something to her brother, but she never had to say anything to her parents, and he was in charge, so she figured it would be okay. Her knees come together and she closes her eyes, biting her lip as she starts going right in her diaper. A soft hissing sound could be heard coming from her crotch, a wet stain quickly forming and spreading through it.
It still took a moment for Andrew to notice, but once he saw what was happening out of his peripheral vision, he blushed heavily and turned towards his sister, realizing she was peeing her diaper right next to him. “C-claire! What are you…?” he started to exclaim, but he stopped himself as he watched her. She was fully focused on letting it all out, not paying attention to him in the slightest. Andrew thought she would be finished after about twenty seconds, but it just kept going, and going, and going. The hissing only got louder, his big, round ears picking up just how strong that stream was within the diaper. It was fully soaked by now, but Claire wasn’t done. She was pissing so much, that the diaper was swelling up under her, slowly lifting her higher upwards on top of the couch. Andrew didn’t realize it, but his shorts were starting to tent up a bit. He blushed heavily as he realized, watching his sister wet her diaper was getting him a bit excited.
After almost three minutes, the mouse cub was finally finished, letting out a huge sigh as she sat on top of her now massively bloated diaper. It was so big, it took up half the couch space on its own. Andrew had kept quiet the whole time, a blush on his face, his boy cock throbbing in his shorts. Once he realized she was done, he quickly shook his head and tried to hide his tent from her, stuffing it up his shirt. “U-um. Are you okay s-sis?” he stammers out that question, having to look up at her from how high she sat on top of her diaper now.
Claire smiled down at her brother and nodded “Mhmm I’m all better now! But I gotta go change now. Can you help me big bro?” she asks quite innocently. Andrew quickly put together that this was quite normal for her, but he couldn’t believe he never saw her do this before. His parents must keep her in a separate room whenever she needs to go. He also realizes why she’s still in diapers, she would flood the toilet every time she went potty. After coming to these revelations, he just nods and stands up, still trying to keep his tent covered.
“O-okay. Uh, how do I help?” he asks, unsure of what to do. “Can you help me down? You gotta carry my diapee to my room” she says, figuring her brother was just as strong as her dad. Andrew just nods and carefully grabs Claire’s waist, bringing her forward and down to the floor, her diaper crinkling quite loudly from the movement. She giggled as her big brother brought her down, almost like a slide at the playground. Once she was on the floor, she took a few steps forward, slowly tugging on the diaper until it comes off the couch with a heavy “thump!”. Andrew let’s out a meep as he felt the floor vibrate from the weight of that diaper, really doubting he could lift it. But as Claire gave him the biggest puppy dog eyes, he just sighed, figuring he could give it a shot. He got behind her and squatted down, putting his paws under the full diaper. Thankfully, it was very absorbent, so none of the pee got onto him. He clenched his teeth and started to slowly lift up that heavy weight, actually impressing himself, the mouse boy not knowing his own strength.
Once Andrew got the diaper fully off the ground, he waited for his sister to start walking towards her room. “Nngh, O-okay Claire, let’s g-go!” he managed to say behind her. “Okay Andrew! Follow me!” the mouse girl exclaims back, starting to waddle towards her room. Thankfully for the mouse teen, it was a short walk to his sister’s room, only taking a few minutes of carrying that huge diaper. It barely managed to squish through the doorway, but they were finally inside her room. Andrew let go of the diaper, letting it plop onto the flop between them, panting heavily. “Hah, hah. W-what now sis?” he asked, never actually having entered his sister’s room. He looked around, and a lot of it was about what he expected. Pink and purple colors everywhere, dolls and toys scattered about, her bed a little bit of a mess in the corner. What he wasn’t expecting to see though, was the huge industrial garbage chute that had been installed in the opposite corner. Now he knows why there were a bunch of construction guys here a few years ago.
“Can you get me out of this diaper big bro? I gotta go take a bath before getting a new one.” Claire explains, having difficulty undoing the straps of her diaper around her waist. Andrew nods and comes around to help his sister, having to really tug on the straps to get them off. Once she was free though, he completely forgot that she would be bottomless without that diaper, as he got a full view of her naked cunny. He blushed like mad, as it seemed that not only did she have a large, hyper sized butt, but her pussy was also huge, the puffy lips nearly coming halfway down her thick thighs. His tent had gone down while he was carrying the diaper, but it instantly came back up once he saw his sister like that. Like previously mentioned, his own junk was hyper sized too, his cock reaching a good 3 feet in length when fully hard, and his balls were the size of melons to go with it. So when he pops a boner, it is very difficult to hide, which Claire immediately noticed, tilting her head with confusion.
“Um, big bro? What’s that? Did you hide one of my toys in there?” she asks with genuine intrigue. Andrew manages to pull his eyes away from his sister’s crotch and put his paws over his own, though it was a feeble attempt due to her already seeing it. “OH! Um, it’s n-nothing sis. Just uh, I’m a bit flustered is all. Let’s g-get you to the bath.” He let out a nervous chuckle as he changed the subject. Claire just giggled and nodded, turning around to head towards the bathroom. Though Andrew did his best, his eyes immediately got glued to her enormous butt cheeks, each one being the size of a small beach ball. They wobbled and jiggled with every step, and he could feel his cock throbbing in his shorts. He knew he shouldn’t be so turned on from seeing his sister like this, but his body had its own plans.
They both make their way to the bathroom, Claire patiently waiting for Andrew to start the water for her, because that’s what her parents did. The teen mouse did his best to stay composed as he turned the water on, putting the stopper into the drain so the tub could fill up. While he was doing so, the little cub pulled off her t-shirt and tossed it on the ground, now fully nude. Andrew glanced over to her and was once again blushing like crazy, having never seen her completely naked before.
“U-uh, you can get in w-while it’s filling sis.” He said, trying to coax her in so at least the water would somewhat obstruct his view of her nethers. “Oh, okay! I want bubbles too!” she responds with glee, stepping into the tub and sitting down in the ankle deep water. Thankfully, their parents invested in an extra big bathtub for the whole family, otherwise Claire’s huge cheeks would have gotten stuck the moment she sat down. Andrew grabs the colorful bottle that had a bunch of bubbles on the label and pours a generous amount into the water, his sister giggling as the suds quickly fill along with the water.
It took about five minutes for the big tub to fill up to her chest, so Andrew figured that was good enough and turns the water off. He figured he shouldn’t just let her be by herself in here, so he just quietly watches as she plays with her toys and bubbles. Despite her having an ass that any adult would die for, she was still a cute cub who liked to play with her toys and watch cartoons. Though, he still had a hard time keeping those naughty thoughts out of his head, his raging hormones somewhat getting the best of him. In the midst of his daydream, Claire reached out and gently tugs on his arm.
“Andrew? Can you help me clean? Mommy and daddy always do.” She asks, giving him those puppy dog eyes again. He quickly snapped out of his stupor and just nods, not quite understanding what she wanted him to do. “Oh, uh, s-sure sis. How do I do t-that?” he asks, trying to shake those images from his mind. The mouse cub hands him the soap and then stands up in the tub, turning around to show him her giant booty cheeks, fur all wet and covered in bubbles. “You gotta clean back there. My butt is too big so I can’t do it myself.” She says casually before using her own little paws to spread her cheeks. Andrew’s mind nearly explodes as he watches his little 4 year old sis spread her butt cheeks, seeing her rather large looking tailhole between them, along with the backside of her puffy cunny. His cock was throbbing like mad in his shorts, but he used all of his willpower to do what his sister needed, swallowing a huge wad of saliva as he shakily puts the soap bar into the depths of her cheeks, rubbing up and down and in and out, getting every part of that area as clean as possible. Claire just giggles as her brother helps her clean back there, though she did feel a little tingle inside her every time his fingers brushed against her hole.
“O-okay, I’m, I think it’s c-clean now” he says with a slight pant, being thankful that the tub was blocking her view of the immense tent he was sporting. She giggles and let’s go of her cheeks, letting them clap together and causing a bunch of bubbles to fly around her. “Yay! Thanks Andrew, you’re the best~” she says happily, before sitting back down into the warm water, letting the soap get washed away. Andrew just shakily nods, soap still in his paw. He knew he’d have to take care of this raging boner at some point, but was determined to wait until Claire was in bed and asleep. Before he could put the soap away, the little cub put her fingers together in a cute way, looking at him again. “Um, can you help clean one more spot big bro? Then I promise we’ll be done.” She asked with a slight blush on her face. She usually cleans this spot on her own, but since Andrew did such a good job with her butt, she figured he’d do great with this too. “Uh s-sure sis, what spot is that?” he asks with a nervous chuckle, not quite putting the pieces together.
Claire doesn’t say anything, but instead leans back until her back was to the far wall of the tub, letting her booty keep her lifted while her hyper sized cunny comes out of the water, in full view of her brother. “H-here.” She says softly, not knowing why she was feeling this way. Andrew’s eyes go wide as his sister presents her huge cunny to him, his round ears feeling like they were burning up from how much he was blushing. He had an initial internal debate on whether or not he should do it, but the throbbing in his shorts won in that regard. He just silently nods, taking the soap bar and gently rubs it along her puffy lips. Claire let out a gasp, a rush of some weird feeling going through her body. It didn’t feel like this when she did it, so why did it feel so… good? She held her legs apart as she watched her brother clean her cunny, letting out soft gasps and moans from the sensations she was feeling for the first time. Andrew was vaguely aware of the noises that Claire was making, but he was laser focused on giving her a good clean. Once he soaped up the outer lips, he set the bar down and used his fingers to apply it all over. He couldn’t believe just how soft her pussy felt, his heart pounding as his fingers easily glide in between the outer lips and cleaned her labia. Though once he accidentally rubbed against a certain nub near the top of her cunny, she let out an even louder gasp, making him suddenly jump and pull his hand away.
“Ah! A-are you okay sis?” he asked with genuine concern, hoping he didn’t hurt her in any way. Claire was blushing almost as much as he was, nodding softly as she twitched from the sudden surge of pleasure she felt. She knew she was all clean now, but she wanted… more. She wanted to feel that again, giving her brother a desperate look. “Y-yea I’m okay… can you, um… rub that s-spot again?” she pleaded softly, her hips gently rolling in the tub to try and coax him into it. It didn’t take much to convince him though, his cock still doing the thinking for him as he nods and moves his fingers back to her pussy. He once again found her puffy clit and started rubbing it in earnest, watching as Claire let out moans and squirmed in the tub. She could feel her body getting quite warm, and it wasn’t due to the water of the tub either. Mommy never touched her down there like this, so she had no idea it could feel this good. The little mouse cub was experiencing something extraordinary, and having those hyper genes also meant that this particular spot was hyper sensitive, sending waves of pleasure through her small body despite the fact that Andrew was barely rubbing her.
“A-Andrew… nnngh… that feels… really g-good…” she managed to say between breaths, feeling something building up inside her. It felt like she was going to pee again, but with the added intensity of the pleasure. Andrew just kept going, determined to not stop until his sister said so. The whole time, his cock had been leaking pre in his shorts, being wildly turned on from touching his sister this way, but he did his best to keep his focus on her. He rubbed her clit for a few minutes, until her moans were getting higher pitched with each subsequent moan, his eyes going wide as it seemed something was about to happen.
“Ah… ah..! Andrewwwww!” Claire moaned out loudly as that pleasure finally mounted, her hips thrusting upwards as a massive jet of clear liquid shoots out of her pussy, her brother gasping as he watched it nearly hit the ceiling of their bathroom before it came splashing back down into the tub and onto the floor. He pulled his paw away the moment she gushed out like that, his heart racing from having witnessed that. He so desperately wanted to just take out his aching cock and take care of it, but his mind told him to make sure Claire was okay. She was left panting heavily in the tub, her legs now tightly together and recovering from whatever just happened to her. She didn’t know what that liquid was, it didn’t seem like it was pee, but it felt close to it. The mouse cub gazes up at her brother, the one who made her feel so good in this moment, still blushing heavily as she now knows how to make herself feel this way.
“T-thank you Andrew. I f-feel better now.” She says quietly, sitting back up in the tub so her bottom half was under the water again. “S-sure thing sis. Um, anytime.” Andrew said with a slight stammer. He looked down at his tent for the first time in ten minutes, blushing hard as his shorts were absolutely soaked with pre. He panicked a little, not wanting his sister to see him like that. “U-uh, I’m gonna go change r-real quick!” he quickly stood up and turned his body away so Claire wouldn’t see it, grabbing the towel off the rack and placing it down on the toilet for her to use once she got out. Before she could say anything, the flustered teen was headed out of the bathroom in a hurry. Thankfully, her mom showed her how to drain the water and dry herself, so she did just that soon after Andrew left her alone.
Andrew quickly got to his room and closed the door behind him, his heart pounding in his chest. He looked down at his immense tent, his shorts absolutely soaked with all the pre he was leaking into them. He huffed to himself as he carefully undid his shorts and pulls them down, along with his boxers. With those now down at his ankles, his 3 foot human shaped cock stood at full attention, throbbing heavily along with his heartbeat. He was no stranger to playing with his cock, having discovered maturation a few years ago, and was thankful that his parents had installed drains in every room. Since they were a hyper family, it was essential to be put into their home as to prevent any flooding from any of them when things got too exciting. He let out a soft groan as he gripped his engorged shaft with both paws, his mind replaying that moment of his sister squirting so hard that she looked like a garden hose on full blast. He didn’t know what that liquid was, but it turned him on like nothing else has before, his paws sliding up and down his member.
Meanwhile, Claire had just finished drying herself, managing to get that towel between your big cheeks to get the hard to reach spots. She grabbed her t shirt and headed back to her own room to put on a fresh pamp, with her previous one still sitting on the floor near the huge garbage chute. But, before she went to get a new diaper, a lingering feeling inside her was giving her pause. Her mind was still processing that intense feeling she had in the bathroom, thoughts of her brother touching her down there, making her shiver and put her knees together. She wanted to feel that again, really badly, but didn’t want to disturb Andrew for it. The little cub hopped up onto her bed and laid down on her back, her large rump naturally lifting her hips for her. She couldn’t help but blush as she spread her legs and looked down at her own cunny, seeing it in this new way, this gateway to immense pleasure, even if she couldn’t put it in those words. The mouse girl reached down with her tiny paws, rubbing along her outer lips to try and find that spot her brother did. Since her pussy was so big and puffy, it took a bit of time to do so, rubbing all around her nether to find it. Rubbing it in general did feel good, but it wasn’t what she was looking for. Then finally, her fingers came across her clit, making her let out a sharp gasp as the sudden surge of pleasure caught her off guard. There it was, the really, really good feeling she was craving. It didn’t take long for her to start rubbing and kneading that spot, unable to keep her voice down as she moans out. It didn’t feel as good as when her brother did it, but it was close.
“Ohhhh mmmf, A-andrew, you m-made me feel so good~” she moaned out, the intense pleasure already making her cunny start to get wet and do some small spurts of that clear liquid onto her bed.
With his big, sensitive ears, Andrew picked up the sounds of his sister, making him stop his paws wrapped around his cock. He had been getting close to cumming, but something about what he heard told him to go check it out. He quickly grabbed a fresh pair of boxers and shorts, trying to stuff his still hard cock down into them, before making his way down towards his sister’s room down the hall. Before he got to the open doorway, he could hear her. Moaning out his name, accompanied by the sounds of wet gushing. Instead of going into her room, he decided to peek around the door, not wanting to interrupt her but still wanting to see what she was doing. The moment he saw, he suppressed a gasp, his cock clutching in his shorts as he watched his little sister touch herself, her bed already quite wet with all the juices she was spurting out. He bit his lip as he debated on what to do next, taking his gaze away from her down to his throbbing tent. He didn’t want to ruin another pair of shorts, so he quickly pulled them down to expose his cock again, but keeping his body turned so Claire wouldn’t see him. The teen felt like he was doing something naughty, stroking his cock as he watched his sister in secret, but he was also way too horny to stop now.
Claire was too engrossed in her own horniness to notice her brother spying on her from her doorway, entirely focused on that building feeling in her pussy. She watched as her cunny was spurting all that liquid onto her bed, half wondering if she was wetting herself, but was in too deep to really care. She continued to rub herself for a few minutes, that feeling building up inside her, with her moans getting louder the closer she got. Andrew knew she was getting close from hearing those moans, his paws stroking faster along his cock to try and cum at the same time as her. Soon enough, Claire throws her head back onto her pillow and cries out as she hits her second orgasm of the day, her pussy absolutely erupting with her juices. Andrew watched as her stream shot so far up, it hit the ceiling of her room and splashed all over the far wall. But it seems she wasn’t done, because a second, and even a third just as powerful jet spurts out of her cunny, splashing against the wall. As Andrew watched his sister drench her room with her squirt, he joined her as his own orgasm hit him too, doing his best to suppress his moans as his cock fires off his thick spunk all over the wall in the hallway, dripping down to the floor as well, the two mouse siblings making messes in tandem with each other.
Once their orgasms died down, Andrew blushed as he realized that he gave the wall in the hallway a new coat of paint with his load. He took a quick peak at Claire, seeing that she was still reeling from her afterglow. He took the opportunity to quickly run to the kitchen and grab a roll of paper towels, bringing it back to the mess he made and starts cleaning it up as best as he could, but not before he pulled his boxers and shorts back up. Thankfully, it only took a few minutes, using up a third of the roll to clean up that sticky spunk off the wall, while the drains in the floor did the rest of the work for him. He manages to get back to the kitchen to toss that big wad of used paper towels into the garbage before Claire came in after him, now wearing a different colorful t-shirt and a fresh diaper.
“Andrewwww, I’m hungyyyy” she whined softly, holding her belly to emphasize her need for food.
“Oh! O-okay sis, I’m pretty hungry too.” Andrew couldn’t help but jump a little from his sister suddenly coming into the kitchen moments after he finished cleaning up. He went to the fridge and opened it up, thankful that his parents had pre made both of them meals for the whole weekend. All he had to do was put them in the microwave and reheat them or just eat them outright if they were just some sandwiches. For dinner tonight, their parents had set up two sets of chicken nuggets with macaroni and cheese inside microwavable Tupperware containers. It was easy enough for Andrew to pop them into the microwave and heat them up per the instructions that were written down on sticky notes attached to the containers.
Once the meals were properly heated up, the mouse siblings went to the couch in the living room to eat and watch cartoons together. After turning on the TV, Andrew noticed that Claire was sitting quite close to him, her hip gently rubbing against his as she ate her nuggets. He couldn’t remember the last time she sat this close to him, but he had to admit, it felt pretty nice. It really seemed like a lot had happened in the past few hours, but the brother and sister felt closer after all that.
The two watched shows for about two hours before it started to get late, at least for them that is. In reality, it was only 10 pm, Andrew having stayed up later than this plenty of times. But for little Claire, she could feel how tired she was, letting out a big yawn followed by a squeak. She rubbed her eyes as she tried staying awake, but it was getting quite difficult for her. Andrew noticed how tired his sister seemed to be, smiling softly as he pets her head.
“Aww, getting tired sis? I think it’s your bedtime huh?” he asks with a chuckle, standing up off the couch and taking the two containers to the sink in the kitchen.
“But but but, I wanna stay up with you…” she tried to protest, but she was having difficulty even keeping her eyes open at this point. Andrew just chuckles and helps his sister off the couch, holding her paw as he leads her back to her room. He helps her hop up into bed, though he couldn’t help but glance over at the wall past the foot of the bed, blushing as it was still quite wet from earlier, along with a lot of her bedding. He wanted to ask her if she wanted a new set of sheets, but since she was already pulling the covers over herself and getting comfy, he figured she didn’t mind it.
The teen boy gave his sister another few pets before moving away, heading towards the door. “Goodnight Claire, I’ll see you in the morning.” He says softly, turning her light off for her. The little cub was so tuckered out, she had already dozed off by the time the lights went out. Andrew went through the house to turn off the rest of the lights, making sure that the doors were locked too, just like his parents told him to. Once everything was secure, he went to his own room, leaving the door open just in case Claire needed him for something. He got undressed and turned off his own light, being in only his boxers as he climbed into bed. The teen wasn’t planning on going to sleep just yet, grabbing his handheld gaming device that was resting on his bedside table and turning it on.
Andrew played his handheld for another couple of hours before he was starting to feel tired too, a big yawn coming out of him. He decides that was enough for tonight, turning his device off and setting it down before pulling the covers over himself, closing his eyes, and quickly starting to doze off. Only a few hours passed before he was suddenly awoken by a soft voice and tugging on his arm. He slowly opens his eyes, barely able to make out the silhouette of his sister next to his bed.
“C-Claire? What’s wrong?” he said sleepily, brain not quite fully awake yet.
“U-um, I had a bad dream Andrew. Can I sleep with you tonight? Since mommy isn’t here…” she asked softly, giving him those patented puppy dog eyes. He was much too tired to argue with her, so he just sighed, nodded, and scooted over to the other side of the bed. Thankfully, he has a queen sized bed, able to for both of them comfortably, even with Claire’s extra large backside. The mouse girl squeaked happily and climbed in with her brother, quickly getting under his covers.
“T-thank you Andrew, I love you big bro.” she says before she snuggles up to him.
“Mm love you too sis.” He replies, still barely awake. He rolls over towards her, his paws down towards his stomach. As he was starting to drift back to sleep, he felt something warm and wet brush against his fingers, along with the sound of Claire softly gasping. He kept his eyes closed, but his tiredness almost immediately disappeared. ‘Did she take off her diaper before coming in here?’ he thought, having a pretty good idea of what he was touching. Claire didn’t really know why she wanted to come in without her diaper, or why she was having these weird feelings about her brother, but all she knew is that it felt really good with his fingers against her cunny under the covers. With how big her butt was, lying on her side made her angle her body a little painfully, but the nice feeling was worth it. So much so, that she gently moved her hips back and forth out of instinct, slightly grinding against his fingers.
Andrew felt her softly humping against his fingers, his heart thumping in his chest. He wondered how far he could take this, keeping his eyes closed as he slowly curls his fingers, hearing his sister gasp again. It seems he hit a rather sensitive spot, as she shivered and humped a little more. While his sister was grinding against his fingers, he could feel his cock starting to harden in his boxers, slipping through the hole in the front. He blushed as it was quickly swelling in size, silently hoping Claire wouldn’t notice it. But it was too but not to notice, as it bumped up against her leg. Claire gasped and stopped her movement, wondering what could be poking her leg. Andrew felt his heart beating rapidly as Claire slowly moved her own paw down to his cock, feeling over it tenderly.
“A-Andrew, is that your… pee pee?” she asked quietly, somehow having known that he was still awake. Or, she was talking to herself. Either way, Andrew took the plunge and opened his eyes, nodding as he put his forehead against hers.
“Y-yea it is sis.” He replies just as quietly, even though they were the only two in the whole house.
“Why is it… um… all big and h-hard? I’ve seen daddy’s but… never like this.” She asks with genuine curiosity. It seems it was going in the direction Andrew thought it was, so why stop there? Might as well see this through.
“Uh… well, it gets like that when um… boys see or think of something they… really like. Like… a deep feeling that feels good.” He said softly, trying his best to explain it in a way that her cub mind would understand.
“O-oh! That’s how I’m feeling too, my cunny feels… really good. Like when you touched it in the bath! And… when I touched it before dinner.” She admits, having absolutely no filter on her thoughts. “that stuff that comes out… I don’t think it’s pee, but it feels really good.”
“Y-yea? Do you… want me to make you feel good again?” he asks, his heart beating even harder, which also causes his cock to throb in his sisters paws. 
She looks up at him with a blush, nodding softly. “Y-yes big bro, please. I really want that.” She almost pleaded to him, scooching in closer. Or rather, as close as her butt would allow. Andrew nods back and gently pulls the covers off of them, not wanting the comforter to get soaked. With the covers off and his eyes adjusted to the darkness, he glances down and blushes more, seeing his sisters pussy already quite wet from the gentle fingering he gave her, along with his hard cock softly throbbing between her legs. Her thighs felt so soft, it took everything he had to not just start thrusting into her. This moment was for her, he’ll find a way to take care of himself after.
“Okay, um, go ahead and roll onto your back.” He instructs her. She nods back and rolls onto her back like he asks. With her giant butt now on the bed, her cunny was already lifted upwards.
“Now uh, s-spread your legs for me.” He says with a hint of nervousness. Even though she was asking him to help, he still felt like what he was doing was wrong. But as soon as she did that, holding her legs apart and giving him a look of deep need, that feeling went away rather quickly. With him still on his side, his cock pressed up against the underside of her butt, still throbbing as he took his right paw and slowly moved it down to her soft belly. He could feel her shivering as his paw went lower and lower until it met her huge, puffy lips down there. In the bath, he played with her clit until she squirted, but this time, he wanted to explore more of her. He felt the nub of her clit near the top part of her cunny, hearing her gasp as well, before moving his fingers further downwards. Claire wondered what her brother was doing, but fully trusted him, as she was already feeling really good down there. Her hyper pussy was already pretty wet, Andrew feeling those juices with his fingers. Soon enough, his fingers were starting to push past the outer lips and even the inner lips. Without much searching, his fingers found her entrance, making Claire gasp out with his name.
“Ah! A-Andrew!” she moaned out, gently arching her back from the intense feeling down there. He took that as a sign to keep going, slowly pushing his fingers deeper into her cunny. To his surprise, her pussy easily stretched open to accept them. He figured it was due to the hyper genes they shared. Soon enough, two of his fingers were now knuckle deep in his sisters vagina. He could feel her squirming a bit next to him, knowing she must be feeling a lot of pleasure.
“H-how does that feel sis?” he asks softly, wanting to make sure he was doing a good job.
Claire could barely form coherent words, her hips thrusting upwards to try and feel more of that good feeling. “mmmf, r-really good… pleas k-keep going…” she managed to say a bit shakily, feeling her brothers fingers so deep inside her. He just nods and pulls his fingers back out, then pushes them back in, starting to slowly finger her cunny. All he could hear now was the sound of her moans accompanied by the wet, schlicking sound of his fingers going in and out of her. His cock was throbbing hard under her butt, spurting pre onto his floor past the bed, while her juices were splashing against his paw and fingers, leaving quite the wet spot in his bed. Without realizing it, he managed to push a third finger into her, stretching her slightly more. He could hear her breathing getting faster, her moans getting higher pitched. Andrew knew she was getting close, but didn’t stop his pace, watching his fingers pumping in and out of her pussy with a fervor.
“Ah… ah..! Andrew, I c-can feel it coming!” Claire moaned out loudly, putting her face into his shoulder. He quickly moved his fingers out of her entrance and up to her clit, rubbing it deeply to finally push her over the edge. With one big moan, Claire thrusts her hips upward as she absolutely erupts, her pussy gushing a huge fountain of squirt. This one was the strongest so far, spurting so far upwards that it hits the ceiling in his room, which was at least fifteen feet upwards. But he didn’t stop after the first gush, continuing to rub her clit to get as much out of her as possible. She moaned more as her brother kept rubbing her, which caused her to squirt a second time, and then a third, each stream being as big as the previous one. His bed and wall was getting absolutely soaked, but he didn’t care. This was all too hot for him to stop. He rubbed her pussy for a full thirty seconds, having lost count of how many times she squirted, until she reached out and pulled his paw away. He looked up at her, seeing her panting heavily as she closes her legs.
“Haah… mmmf it’s t-too sensitive now Andrew… but… that felt so good…” she says between breaths. The teen just blushes and nods, having gotten caught up in the moment.
“S-sorry sis. Just… watching you gush like that is… really sexy.” He admits, his cock aching incredibly hard under her. She could feel that throbbing under her, looking at him with another blush.
“But, what about you? I wanna make you feel good too.” She says softly, looking at him shyly. He blushes in return, his cock doing the thinking. With how much he pleasured her pussy, he figured she’d be too tuckered to do anything else with that. But, she did have something else really liked.
“Uh, well, if you really wanna… turn over for me.” He instructs softly. She nods and quickly rolls over onto her belly. As soon as her enormous butt came into view, Andrew practically drooled. With it now this close and in full view, it looked so big and tantalizing. He carefully sat up and straddled her legs, his paws gently kneading into her cheeks. They were so big in comparison to his paws, they practically sank into her plush rump. Claire let out a soft gasp and moan from having her butt played with. It didn’t feel as good as her cunny, but it still felt nice. Once Andrew got a nice grip on her cheeks, he gently spread them apart. He blushed more as he discovered that, not only did she have a hyper pussy, but she also had a donut for a tailhole, tucked nicely away between her cheeks. With how puffy it looked, it made his cock throb even more, but he didn’t want to ruin the moment by suddenly putting his cock into her ass without asking first. So instead, he settled with putting his raging boner in between her cheeks, which almost completely hid his three foot cock, and squeezing them around it. He moaned as he squished those plush mounds around his member, his hips starting to buck as he hotdogged his little sisters giant ass cheeks. With every thrust, his hips plapped against the underside of her cheeks, making them wobble heavily around his cock, which brought him even more pleasure. He could only moan out, this feeling so much better than his paws did. Claire moaned with him, the feeling of him humping at her butt like this being a little weird at first, but was starting to feel good for her too. With his cock grinding against her puffy pucker, should could feel a different kind of pleasure building, which made her instinctively push back into him.
“Nnngh, you’re butt feels s-so good sis… I’m not gonna l-last long.” He managed to say between pants and huffs. His cock was spurting pre all the while, coating Claire’s back and getting her fur all sticky. She didn’t know what was gonna happen when her big brother hit his big moment, but she was happy to let him finish while doing this. After a few more minutes of constant thrusting, Andrew could feel his balls tightening up, making him grit his teeth and grip those cheeks harder.
“Mmmf, h-here it comes C-Claire…!” he moans out before he arches his back and thrusts one last time, moaning out as his cock shoots thick ropes of his spunk all over his sister, past her head, and hits the headboard of the bed. He shot nearly fifteen streams of cum, the most he’s ever done since he discovered masturbation. Once he was finished, he pants and looks down at the damage, blushing heavily as he absolutely coated his sister in his seed, along with the pillow and headboard.
“A-ah, I’m sorry sis. Are you o-okay?” he asks while removing his cock from her cheeks, genuinely concerned about her.
“Y-yea I’m okay big bro. What’s this… sticky stuff that’s all over me?” she replies, feeling it matting her fur on her back and head.
“It’s uh, called cum. You know how you squirted a bunch of stuff before I did from feeling really good? That’s what guys do when they feel that way” he tries to explain. He hops off of his bed, wanting to get everything cleaned up after the mess they made. She just nods and climbs out with him, wanting to get the cum out of her fur. They agreed to go take a quick shower together, with Andrew helping his sis clean out all of that spunk on her back and head. Once they were all clean again, he took the time to change his sheets and clean off the spunk from his headboard. Though, he had no way of drying off Claire’s juices from the ceiling or wall, but he secretly didn’t mind it. After all that, they finally climb back into bed together, both exhausted from that naughty activity they just did. Before they drift off to sleep, Claire kisses him on the cheek, smiling to him.
“Thanks big bro, I love you lots.” She says softly, before closing her eyes and immediately snoozing. He just blushes and smiles, kissing her cheek back.
“Goodnight sis, I love you lots too.” He replies, closing his eyes as well. Something tells him that their lives wouldn’t be the same after this, but he thinks, it’s for the better.