> When Did My Nerdy Sister's Butt Get So Big?!
>  by darf
> --------------------------------------------------------------------------

> I enjoy sizable equine posteriors and I do not possess the ability to prevaricate statements
> --------------------------------------------------------------------------

It was the summer before Shining was to leave to join the Royal Guard. A perpetual summer, that seemed to stretch out in either direction as long as it needed to in order to prevent the sense of time actually passing. Shining swore he'd been a week away from leaving for months now. But it really was this week, after all, and he was almost done packing besides.

Naturally, the family was reacting in different ways to their prodigal son's imminent departure. Twilight Velvet had gone back into a sort of 'homemaker' mode and, when she wasn't putting around the kitchen making more baked goods than anypony in the house could consume, would catch Shining Armor off-guard with a hug from around the hallway corner, complete with crying fit and 'oh my baby boy what will we do without you' etcetera.

Shining's dad, Night Light, had instead gotten more distant, like he had been charged to give a big speech the night before an embarking platoon, and suddenly found he'd left the notes in his other pants pocket. He'd start to say something that sounded meaningful and wise when he ran into Shining, then stumbled off until his rambling became pure air, and ended with an awkward pat on the back before he went to the living room to watch hoofball. He'd been watching a lot of hoofball lately.

Then there was Twilight, and it was hard to tell which part was due to Shining's departure and which were just the muddled-together colours of icing in her cake of puberty1. Twilight had started changing so fast Shining barely recognized her. Still the bookishness remained, the overall shyness and studying and "What is it? What do you need?" when you opened the door to check on her. But all that introversion had been funneled to a single point, and it was becoming impossible to tell the separate pieces apart.

For one, even though Twilight had always spent a lot of time in her room, the amount as of late was practically a quarantine. Shining Armor remembered seeing her maybe once in the last week, and that was in the middle of the night when he got up to use the bathroom and saw his sister huddled over the sink with a bowl of cereal, hastily shoving the mouthfuls of milk and sugared rice into her mouth while making sloppy chewing noises and dribbling a healthy amount of the milk down her chin and into the sink. She didn't seem to notice him until he flicked the light off, and then her eyes froze like a yak under a floodlight, staring back at her brother as he slowly ambled past the kitchen on his way back to bed. Slowly chewing a mouthful with milk dripping down her chin. Munch. Munch. Munch.

There was her taste in reading material as well. Somehow Twilight had neglected the 'imported texts' section of the library all her life, and was only just now diving head-first into the world of upside-down overseas perspectives. It had started at books, regular ones that were full of words going in the direction Shining was used to—but now she was reading backwards ones, and ones with pictures, and ones with confusing little squiggles Shining could make neither heads nor tails of even after turning the book in question in every direction.

Lastly, there were the video games. Shining Armor was no stranger to virtual entertainment, though he greatly preferred the genuine act of going out into the field and getting his hooves dirty. Somehow tapping buttons on a piece of plastic to make a picture of a pony do something had never translated directly into 'fun'. But with Twilight, it was a different story. Hundreds of hours sunken into her new Neighponese RolePlaying Games—NRPGs, for short. Shining tried to watch her play one, once, but after twenty minutes of cut-scenes and no actual evidence that his sister's button pressing was contributing in any way to the action on screen, Shining had given up, under the presumption that some cultural trends just couldn't be translated for everyone.

It was a bit of a stinging sensation, all the same. Couldn't a bookworm pretend to be a regular earthworm for at least one day? Couldn't she peek her head out and say goodbye to her brother, without worrying about hungry-looking robins overhead? Shining felt like he'd been reading too much. Old pony words were starting to creep into his brain. Like 'lagomorphic'. He wasn't even sure what that one meant, to be honest2.

He'd been basically done packing for weeks, but every other day, something seemed to pop up that he'd forgotten to make a place for. One last 'after-thoughts' box was already half-way full and threatening to explode into the surrounding packing area if it wasn't contained soon. Shining sighed and reached for his trusty roll of duct tape.

Which was empty. Drat.

Shining checked the kitchen, and the 'miscellaneous' drawer his mother insisted on keeping in the hallway closet, which contained a haphazard assortment of cords, metal bits, wooden things, and any other materials which could have suddenly and mysteriously congealed into a semi-useful implement. Shining dug around for a while, concluded he was unlikely to find a way to keep the box closed with wooden clothes-pins, and headed off for his sister's room. Maybe she had an extra roll lying around after her failed attempt at assembling that giant robo-pony. The paint-job still haunted him in nightmares.

"Hey, Twily," Shining said as he opened his sister's door, knocking twice before turning the knob. "I'm trying to finish packing and I was wondering if you'd seen the holy shit what?!"

Twilight was up on her bed, sitting down with a few pillows resting under her head against the headboard. Her hind legs were spread, her pussy was wide open, shiny, a little pink, glistening, and staring Shining Armor right in the face. Twilight's hooves were on either side, stretching herself wider, and she was staring between her legs at her own pussy as though it was a new specimen she'd selected for study.

It took her a few seconds to notice Shining had walked in. Then she noticed him.

"Oh, hi, Shiny!" she said. Didn't move an inch, aside from a little wiggle on the bed. "What's up?"

Shining Armor's brain collapsed on itself from several different directions. The area responsible for controlling his penis was making requisitions from every other available department, and construction plans to erect a new model were well underway.

He was getting hard looking at his underage sister's pussy, to put it bluntly.

"What the hell are you doing?!" Shining asked. He shut the door, glancing nervously from side to side as though it might cover their tracks in case their parents had seen.

Twilight considered Shining as though he'd asked about the weather.

"Oh!" she said, eyes gleaming suddenly with understanding. "You mean this?" She pointed with one hoof to her wide-open pussy, which was, yes, Shining could tell, more than a little wet, and contracting ever-so-slightly each time Twilight took a breath.

Is that a rhetorical question? Are we supposed to answer?

"Yes," he said. "That." Shining gestured awkwardly between his sister's legs, looking and not-looking in equal parts. "What are you doing?"

Twilight shrugged and smiled.

"Well, I was up late last night, and when I went to the kitchen to get something to eat, I heard Mom and Dad making a lot of noise. I went to see what they were doing, and Dad had his hoof and tongue right here—" she pointed with the hoof still holding apart her underage slit. "He was moving his tongue and hoof really fast, and Mom was making a ton of weird noises, she sounded really loud, almost crazy..."

Shining's erection was at full-mast, and until he started wearing a regular uniform in the guard, there was nothing to conceal the rather embarrassing fact from his younger sister. He shifted sideways and tried to hide the dangling length under his hooves. Twilight gave him a curious look, but either didn't notice, or did, and was very good at pretending not to.

So she walked in on our parents having sex. Bound to happen eventually.

"And anyway, I wanted to see what all the fuss was about. So I was checking it out to see if there was something special that happens when you touch there." Twilight ran a hoof up and down her lilac lips and traced a bit of her filly-juice over her gentle folds and the outside of her hoof. Her body rocked up against her hoof, hips moving to create friction, and a little moan escaped her lips... but then she stopped, and stared at her brother.

"It feels okay, but I don't think I'm doing it right," Twilight said, frowning. "Dad was doing it really fast, and he had his tongue too... oh!" A light-bulb went off somewhere in the distance, and Twilight jumped up from the bed and darted to her gaming setup, a nest of wire-squids and power-supplies tangled around a scattered collection of discs and memory cards. She grabbed one of the controllers connected to the currently operating console, with the little green light on in the corner, and passed it to her brother.

"Here," she said. She pressed a direction on the control stick, and, as Shining turned his head to the screen to watch, a tiny pony-figure wearing glasses and a fancy dress began to run through a field of virtual grass and hills.

Shining took the controller and stared at it. He held the direction specified by his sister, and watched the pony in the game run up against a mountain wall, over and over and over again.

Twilight beamed at him.

Huh?

"...huh?"

Something had been lost in translation, evidently.

"Oh," Twilight said, the little 'I-forgot-that-part-didn't-I' creeping into her voice, the muffled and hidden excitement of showing her brother this little slice of her private utopia. "When you run around in tall grass, you get into encounters. And when you hit the monsters, or the monsters hit you..."

Shining watched the T.V. screen spin and blur as he was sucked out of the shimmery field of green pixels and into a side-view combat with some grumpy looking giant tortoise-type-things.

When one of the big turtles attacked, and bonked the pretty pony with the dress and glasses on the head, she made a cute, slightly suggestive sounding 'unh!' noise. And the controller shook. Vibrated, really.

Shining's Royal Guard training hadn't prepared him for every scenario in the world, but problem solving on the fly was a key component to proper security.

"Oh," he said. Another turtle swung, and the piece of plastic in Shining's hooves buzzed frantically.

"So you want me to..." he said.

Twilight smiled and nodded. She spread her legs even wider, and lifted up her hind-legs a little, giving her brother a full and perfect view of her sopping pussy and...

Has she been putting on weight or what?

There was no doubt about it—where Twilight's introverted tendencies and aversion to leaving the house had in the past translated to a scant diet among inconsistent meal-times, resulting in a rather twig-like bookworm if ever Shining had seen one—now that it was the summer, or that her brother was leaving, or that some combination of events had melted together in just the right way, Twilight had discovered what may as well have been a hidden life-long affection for chocolate snacks. Once she found out there were imported varieties, there was no turning back, and all the bowls of cereal and late night energy drinks during another twenty-four hour grinding binge had finally started to add up.

Twilight's ass was fat as fuck.

And there she was, both her squishy cheeks, smooshed onto the bed and waiting for her big brother to take the controller in his hooves, press it up against her pussy, and combo monsters until...

Well... until what?

Shining didn't want to have a conversation with the nagging voice on his right shoulder begging him to run away back to his room. He'd been listening to them for long enough, and a fat ass was an immutable constant of value that must be agreed upon across frames of reference. His hard-on gave an extra twitch in agreement.

The controller felt oddly smooth and elegant in his hooves. He wondered how much Twilight had used the plastic to wear patterns in the buttons.

Nothing was happening. The pony on the screen was just standing next to the monsters.

Shining tilted his head quizzically towards his sister.

"Oh," she said. She pointed towards the bottom button on the right side of the controller. "You have to use that one to select your character. The one that looks like an 'X'. Then you pick a move, but make sure if it's a special move that you have enough SP to cast it..."

I'm just gonna press 'X' and see what happens.

The dual-handled piece of plastic began to vibrate. Bzzt, bzzt.

Twilight smiled.

"There you go!"

Now there was just the matter of... uh...

Shining considered strongly whether he wanted to help his underage sister masturbate the week before he left the home for good.

Possibly there was no better time to do it.

The controller felt heavy. He lowered it towards Twilight's sex, both his eyes and his sister's locked on the protruding handle. Finally, it pressed up against Twilight's slit, poking just a bit inside with the smooth, rounded edge.

Twilight giggled and wiggled her hips. Her pussy was petite and adorable, but her butt was big, and it took most of Shining's willpower to focus on the screen and the button he was supposed to be pressing. 

Heh. Pressing Twilight's 'button'...

"Shiny! Remember to take your turn! The monsters can't act until your characters are done."

"Oh. Right. Sorry."

Shining tapped the button. The menus on-screen weren't entirely inscrutable, and he even managed to select what looked like a special attack. The griffon in his party was wielding a big, curved blade, and she swung it around the entire group of monsters followed by shimmery, shiny after-effects. The damage numbers popped up a second later, and the controller rumbled into action, following the hit-sound of the giant blade and vibrating for a full two seconds before it finally went back to rest.

"Ahhhh!"

Twilight took her eyes all the way off the screen for the first time. She even closed them as her head tilted back.

The buzzing sound was muffled slightly by the wetness of Twilight's sex. It sounded a little bit like it was running underwater.

Now it was the monsters' turn. They went one after the other, big hulking turtles somehow cropped up in an ancient forest. The pattern went rather quickly: clunk, bzzzt. Clunk, bzzzt. Clunk, bzzzt.

Twilight let out a tiny cry with each buzz, and bucked her hips up at the controller.

It was difficult to split attention between the oddly-intricate mechanics of the game and the even more intriguing systems between his sister's legs. Shining followed a small urge to push the plastic handle against his sister's cunt, and he was rewarded with the slosh of extra filly-juices lubing up the handle. Twilight's lips parted perfectly for the rounded edge, and Shining found himself wondering how easy it would be to switch one tool for another.

"Shiny," Twilight said. Her breathing was ragged, and her face was flushed. "That feels... so good. Why didn't anypony... tell me about this?" Clunk, bzzzt. "Ahhh!"

It was Shining's turn again. He scoured through the special moves this time, looking for the lowest items that might use up the most SP, and therefore have the most hits. Everyone in the party queued up an action, their weapons tucked in bad-ass poses while they waited.

When the party unleashed its attacks, the controller started whirring so fast it reminded Shining of the sound of his mother's vibrating toothbrush before bed. Though, he could swear he'd heard her brushing her teeth three or four times a night the last few weeks...

"S-shin-ing... Something's... oh no, it feels like... I'm gonna..."

The controller was still buzzing at full speed. Shining rubbed it up and down his sister's slit, making sure to press hard over her little clit, hidden away just above her dripping, underage lips.

Twilight gushed so hard it sounded like somepony running a hose against the side of a shed. Shining's mouth fell open in tangible disbelief as he watched his little sister scream, shut her eyes, and buck her hips up over and over again while she sprayed a hot torrent of filly-cum all over the bed, her brother, and—

"Ah, the controller!" Shining yanked the plastic away just as the buzzing was coming to an end. However excited his sister was at the moment, she'd be less pleasant to deal with in the aftermath if her favorite controller got... 'water' damaged.

Twilight muffled her moans with her hoof as she came down from her orgasm, but in Shining's opinion the effort wasn't much worth it—for one, their parents were out for the day, shopping or running errands or whatever it is parents did when they were out—and for two, Twilight was still so loud that if their parents had been home, they would have heard anyway. Twilight's hoof barely helped at all.

Shining Armor wiped off the side of Twilight's game controller on one of the random pieces of dirty clothing scattered around the room. Unlike Shining, who was grilled every day to make sure he'd cleaned up properly, Twilight Velvet and Night Light had given up with his sister after months of badgering her to at least keep the books in piles, as opposed to haphazard mounds and hanging from various appliances. At this point, Twilight's room was what could be professional referred to as a 'lost cause'. Somehow, none of the dirty dishes, dirty clothes, or bags of left-over takeout food had bothered Shining til now. Maybe watching your little sister cum all over herself had that effect.

Twilight was panting on the bed, her legs lowered and shuddering. She wiped her forehead with her hoof and stared down between her legs at the pool she'd left on the bed.

"Wow," she said.

She looked up at Shining.

"Why didn't anypony tell me how good that feels?"

Shining shrugged awkwardly.

"Well, uh, it's something you're supposed to, kind of, learn on your own, while you're growing up—"

"So it's even better if I have somepony I trust to teach me. Right, BBBF?"

Twilight had shifted on the bed, turning herself around and navigating around the wet-spot, to rest her chin on her hooves and stare into Shining's eyes while waggling her tail behind her head. And her butt, the outline of which Shining could easily make out as it bounced from side to side.

"Right. Well, the thing is, we've probably already done way too much, so before things get too crazy, let's—hey, hey, cut that out!"

Twilight had made a dive for her brother's cock, and managed to get her lips around the tip and start licking it before he pulled away. His hardness was doing him no favours in negotiating his position, and the glob of Twilight's spit dangling from the head of his prick dealt a serious blow to his remaining reserves of willpower.

Make sure you have enough SP to cast your special move.

Huh?

"Come on, Shiny!" Twilight whined. She wiggled on the bed, turned around and pointed her big, purple butt and dripping underage pussy right at her brother's face. "You're my big brother. I want you to feel good the way you made me feel. Doesn't it feel really good if you stick your thing in there too?"

Shining raised an eyebrow.

"Mom and Dad again?"

Twilight nodded eagerly, her tongue hanging out slightly.

"Uh-huh! After Dad finished licking Mom, Mom got on the ground and Dad got behind her, and then he got up and stuck his thing in her from behind! I watched!"

Shining eyed his sister. 

Was this a natural byproduct of nerdy seclusion, or something more specific?

Ah. He could smell Twilight's sex from here. He could practically feel how wet she was...

"Come on," Twilight said, continuing her butt-waggles and wafting her tail over her dripping hole. "Don't you wanna stick your thingy inside your little sister's, uh... um..."

"Pussy," Shining said. He put a hoof on one of Twilight's big, round butt-cheeks and slapped it ever-so-gently, watching the jiggles go. His cock was hard, and lined up easily between his sister's lower-lips. She was fucking soaked.

Twilight moaned breathily when she felt the head of her brother's cock against her entrance.

"Ohhhh, Shining... please, I can't take it, I wanna feel good again... put it in, pretty please..."

If anyone asks, just say she seduced you.

Shut up.

Shining braced himself, then thrust his hips forward slowly. He couldn't take his eyes off his shaft as it slid inside his sister's pussy. His sister's pussy. Twilight's pussy. The words kind of blurred together in his head, it felt like he was breathing them in through the air.

There. All the way. He was bottomed out inside Twilight's little cunt.

"Hah... hah..." Twilight was breathing loudly, like she was barely able to contain her voice around the feeling of the big, thick thing shoved inside her. Her butt-waggling had stopped as she felt her brother's balls slap against her clit, but once Shining had settled his position and given Twilight a chance to fully get used to her first cock, Twilight had started rocking back and forth immediately, more forward and back than side to side, but still slipping in the occasional circle-shaped wiggle to keep her brother on his... er... hooves.

It felt impossible to move. Too hot. Too wet. Too tight.

Too much big, fat, butt, begging for him to coat Twilight's purple fur with his sticky white load.

Shining wiped a bit of sweat off his forehead. Twilight's breathy moans punctuated the silence.

"I'm gonna move now," Shining said. "Okay?"

Twilight looked back and nodded, her eyes steely and determined.

"Uh-huh," she said. "I wanna feel it move in me."

That can be arranged very quickly...

Shining was new to this whole sort of thing as well. He'd fantasized, seen the occasional 'risque' scene in a movie, and even had a magazine borrowed from a school-friend of mares and fillies showing off their naughty bits in front of a camera, usually surrounded by a lot of fancy-looking pillows... but those were all images, things he could see but never touch for real. Twilight was his sister, somepony he'd held and hugged and cared for all his life. And now she was in front of him, shaking her over-sized butt, and begging for more as his cock slid, torturously slowly, out of her hot-wet clenching cunt. Planting her face in her pillows and moaning gutturally as he shoved his cock inside again, faster this time, letting Twilight get her first taste of what it felt like to be really slammed, fucked, rutted. 

Shining felt a fire burning inside himself that had come from nowhere. Burning over all the years, finally made visible.

He licked his lips and smacked his sister's ass with his hoof. It jiggled satisfyingly around his cock.

"Ahhh! Shiny? What are you—ah!"

Shining Armor gave Twilight another smack, on the cheek he'd ignored until now. Nothing hard enough to leave marks, barely even a tickle. But, for his sister, who was already in over her head, drowning in a new type of pleasure...

"Oh, Shining... I feel funny again, it's so good, I think I'm gonna—"

"Cum," Shining interrupted, grunting between thrusts as he bottomed out his cock in his sister's pussy. "When you feel... really good... from down there. It means you're gonna cum." Shining shook his head and flung a bead of sweat off the tip of his mane. "Cum for me, Twily."

"Oh, Shining, I'm... cuuuuummmiiing..."

It was even wetter than the first time. Shining struggled to keep hold on his sister's rump as she bucked and squealed and clenched fiercely around his shaft. It was too much to take after a while, and he had to pull out or risk letting Twilight's cunt squeeze him so hard something broke off. Either that or she'd milk a load out of his balls before he was ready and leave him with a very sticky potential mistake one week before leaving for good. Shining wondered if Twilight Velvet had at any point taken time with her daughter to discuss birth control.

Shining rubbed the head of his cock against his sister's clit. She squealed louder as her orgasm went on, legs shaking, until they gave out, and she fell onto the bed with a tiny 'splash', adding even more filly-juice to the already soaked bedspread.

The room reeked of sex. Shining didn't know if he'd ever been so hard in his life.

Things probably could have gone on like that forever, banking enough experience to level Twilight's RPG party to end-game... but Shining felt like he was only lucky enough to get one chance like this in a life-time, and what kind of big brother would he be if he left his little sister hanging like this? All, butt stuck out, juices dripping, quivering in front of him and waiting to be taken... it was practically his responsibility to take over from here.

His cock was already soaked in Twilight's juices. All the lube necessary.

Twilight murmured when she felt her brother pawing and prodding at her backside. She didn't seem put out, just half-there, recollecting her senses through the haze of her orgasm. Still floaty as he pressed the tip against her rosebud, then grabbed each cheek and slid forward...

"Shining," Twilight said hazily, "does it feel just as good in there too?"

Shining nodded. Then he realized his sister was barely able to keep her eye's open, and therefore probably hadn't seen his nod.

"Yeah," he said. "It feels really good in there too."

For me, at least.

Shut up. We don't know either side from experience.

Yeah, but look at that ass...

Shining looked at that ass.

"Twilight," he said, "how much chocolate have you been eating lately?"

Even in the fog of her newfound lust, Twilight managed to catch the question with a giggle. She shook her butt at her brother for good measure, wiggling her rump over the head of his cock and bouncing both her cheeks up and down like jelly-ful pancakes3.

Shining groaned. Twilight was moving before he could, shoving her butt back and slamming more of him inside. He barely had time to watch before Twilight had worked herself all the way back and buried her brother's cock inside her underage butt.

She stopped there for a moment, her eyes half-open, heart-pupils, tongue lolling out of her mouth.

"Wow," she said again. She wiggled back and forth on her brother's cock. It felt big inside her butt.

Shining groaned again, finally letting himself be swept up by his sister's intoxicating allure and vowing not to look back. Twilight's butt was even tighter than her pussy had been, and all the while, that look on her face, like she knew, they both knew, kept saying the words over and over again in their heads.

My sister's butt. I'm fucking my sister's butt.

Shining wanted to get a-hold of himself so he could put the cushion of his sister's padded cheeks to work, but Twilight had taken over, was so drunk on another new sensation that she was gorging herself on it, slamming over and over again, bottoming out with the head of her brother's cock poking up inside her and making her squeal and moan every time. When she moved forward, and felt the whole thing slide out, imagining what it would look like if she could turn back and stare, could even keep her head straight... oooh, she wanted to see so bad, she wanted to see what it looked like as her big brother's cock slid into her butt...

"Twily," Shining said. He was managing the odd counter-thrust to Twilight's stupendous momentum, but mostly it was a ride for his life, his balls bouncing with the rhythm of Twilight's backwards thrust, each slam edging him closer to the finish line, a spray of white, hot good that would coat the insides of her butt. The insides of his underage sister's cute, fat butt, coated in his cum. "I'm not... gonna last much—"

"Do it in me!" Twilight shouted, half-delirious. She managed to crane her neck around for a moment, to stare into her brother's eyes, to still her backwards bouncing for just a second to let her brother feel his whole cock engulfed by the velvet-smooth insides of her ass. 

Shining Armor felt his breath leave him. He could have tapped himself over the edge.

"Do it in me," Twilight repeated. "I saw Dad, last night, he made Mom all sticky... I want it in me." Twilight shook her ass on Shining's cock, making him groan. "I want it in my butt."

"Twi—" Shining gasped. He could feel his balls tightening.

"Do it in me," Twilight said one last time, her voice lowering to an almost whisper. She ground herself backwards onto her brother's shaft, planting him as deep as he could go, even deeper, slamming the head of his cock so far up her ass she could practically feel it in her throat. She kept repeating the words to herself, so quiet they almost didn't count. 'Do it in me... do it in me. Do it in my butt.'

Shining Armor came without any more warning. It felt like a bullet-train was rushing from his balls to the head of his dick.

Twilight took over sound for both of them, moaning so loud a few of the glass-frame pictures on her bed-side table began to vibrate. Even though her brother's cock was buried firmly in her ass, Twilight's pussy felt every inch of it, the same way she'd throbbed and squeezed around when her brother was actually inside her there. She could feel another orgasm coming, another waterfall, she was definitely going to have to do the laundry at some point after this, it'd been about three weeks, after all—

"Oh, buck!" Twilight caught herself swearing, and felt even naughtier for it. She'd never felt anything like her brother's cock in her ass, spurting out jizz. It felt all warm and wet and hot and sticky, like somepony was giving her little licks from the inside, all while she was rocking up and down on her brother's shaft, getting slipperier and slipperier by the second. 

Twilight looked back again, this time craning to get a glimpse of the point of contact between their sibling sex. Sure enough, when she watched for just a moment, she could already see a peculiar white liquid oozing out around her brother's cock and beginning to drip into the bed-sheets to join her filly-juice. There was more of that now, too, and Twilight wondered if there was a well somewhere inside her responsible for storing the stuff up. Because she had a lot of it.

Behind Twilight, Shining could only manage a few sparse grunts as he emptied his balls into his sister's butt. The words on replay had faded out into nothingness the second his orgasm hit, and now he felt like he was several feet up, steering his own head around, watching himself watch his own cock, his own cum empty into Twilight's ass, leak all over her sheets, join the drenching downpour of Twilight's girlcum that seemed impossible to quell. Shining wondered whether his balls were in a similar condition, it felt like every time he was done, another jolt and spurt of semen would shoot up his shaft and join the burbling drip from between his sister's luscious butt-cheeks to the soaking-wet bedspread. Shining made a mental note to help his sister with laundry before he finished packing. It looked like it'd been at least a week since she'd washed anything. This was just a good excuse.

You can't blame a big brother for wanting to help his little sister, right?