The doctors said it wasn't anything abnormal. Rare, yes, but not unheard of. There were hundreds of cases across Equestria, they assured her. She'd heard about it herself before, in passing, and she did research after getting the news, but she never would have expected it'd be something she'd have to deal with in her own personal life. She'd never expected it would be something relevant to her little Button.
And he was little. Barely above eighteen, the age at which the signs of his condition usually started to show, he stood somewhat short, and combined with her own height that meant he had his eyes level with her rather ample, shoulder width chest. To her, he would always be her little colt, even if he was growing. And boy was he growing.
It was a magical mutation, apparently. Rare, and his was the only case in Ponyville, but well documented. The details and ramifications were still being researched, but it wasn't dangerous or harmful in any way, not besides the obvious discomforts it could bring. The signs would appear during the stages of physical development in late puberty, but traces of the magic tied to it would manifest earlier on, which was how Button's case had been noticed during a routine checkup.
The symptoms, if that was the right word, resulted in exponential growth of some body parts in the mares and stallions affected by the mutation. Typically, almost always, those were the genitals and other sex-related areas. The growth would be regular and noticeable, but not painful. Quite the contrary, in fact, though that had its own set of problems.
Button's diagnosis had come a month prior, and since then the effects had already become more than apparent. All his pants and shorts and underwear had become much too ill-fitting, and his mother wasn't even sure if it was worth buying him replacements yet when she knew he was only at the start of his growth process.
Button's cock and balls, to put it bluntly, were becoming massive. His shaft, even soft, was multiple times longer than even an adult's erect cock would be, closer to two feet than one and a half by that point. His balls were so heavy and wide he had to keep his legs spread when he sat and walk awkwardly most of the time, their size about comparable to that of a pair of basketballs and growing still. And that wasn't even the worst of it. Oh no.
Button's cock was leaking. Not merely proportionally to his growth in size, either. He would outright drench his underwear in precum, and it had gotten to the point where he'd wear special clothes when he had to go out and just stay bottomless when he was at home, sometimes with a nearby bucket or basin to let his cock drip into. Cleaning up the stains he accidentally left on the floor was taking more and more of his mother's time, and his sheets needed changing every day. The musk of his obscenely growing cock filled the house at all times, simply impossible to get rid of at that point.
And that wasn't all. Button's mother had noticed other changes too. Not in Button, no, his condition seemed wholly and exceedingly focused on his cock and balls. Rather, she had realised she herself was changing. She wasn't certain yet, but she could feel it. Her clothes felt a little tighter, her bras a little harder to get on, her panties dug deeper in the crack of her already huge and bubbly ass. She'd always had a body she was quite frankly proud of, but now she was quite certain her already sexy proportions were getting an extra push.
That was a possibility, apparently. The latent magic associated with the mutation could influence ponies who spent a lot of time close to those affected, and especially so if they came into contact with secretions from the affected areas. Button's mother didn't really have a choice though. Her son's dick wouldn't stop leaking, and someone had to look after the house. She could only hope things would become stable eventually.
A few weeks later, things had not stabilised. They had, if anything, wildly escalated.
Button's mother wasn't sure how it had started exactly. If Button had had similar thoughts before his condition had manifested, or if she should have acted differently about his proposal. The fact of the matter was that they were much past the point of worrying about those things, and her mind was focused elsewhere. It took a lot of self control for her to do what she needed to without going too far.
It had all seemed reasonable at first, or maybe she was already too out of things by then to see it as wrong. Button was pent up. He wasn't merely leaking, his balls were actively churning with cum. He needed a way to relieve himself, as being so backed up was uncomfortable at best, and outright painful at worst. The doctors had agreed that the best and only way to deal with it was for him to cum, as there wasn't really a way to halt or slow down the mutation until it stopped by itself. So Button had started masturbating, often, and with buckets ready to catch his seed.
And then he'd asked for a seemingly innocent favour. He'd asked his mother to help him get off.
She'd hesitated. Of course she would have hesitated. But she hadn't outright said no. Their situation was anything but normal. Button had a medical condition, and it was her duty as a mother to help him how she could. Button was feeling physical discomfort, and there was an easy solution to it. Of course, he could just jerk his huge cock off himself. He'd been doing that. A lot. Sometimes while his mother was right there.
Which wasn't something to be held against him all things considered. For one, it wasn't like her seeing his dick was anything unusual anymore, and the same went for the copious amounts of bodily fluids he let out. For two, with how things were, it was best for everyone if Button relieved himself when and where he needed to instead of leaving for another room. If it happened that his mother had stuff to do in the same room he was doing stuff in, then they would just have to live with it. It was her job to clean his messes anyway.
But still, there was a difference between being in the room when Button jerked off and jerking him off herself. There was a line between the two. A line she didn't want to cross, back then. She'd told him as much, made it clear that his condition didn't mean he could just take advantage of her like that. Button had insisted. Just once, he'd said. He was really pent up and struggling, and having trouble doing it himself.
Could anyone truly blame her, a mother, for giving her child what he asked for so strongly? In the end she'd agreed to it, if just once.
It had become a daily ritual. Then even more than that. Every time Button needed to get off he'd call for his mother, and that was multiple times in a single day as his mutation kept making his genitals bigger and his semen production greater. She'd tried to resist, more and more weakly as the days went on, until she'd stopped resisting at all. There was nothing wrong with a mother helping her son, she'd tell herself.
Truth was that, despite herself, she was into it. It was hard to put into words, but she liked it. She didn't want to accept it yet, but she couldn't deny it either. The images of Button's massive, throbbing cock lingered in her mind long after he'd left for school after his morning sessions, and the stench of his arousal was ever present and impossible to get properly rid of. His mother found herself thinking about him more and more. How much he'd cum. How big his cock was. How intoxicating his musk felt.
She still had standards, of course. She hadn't taken her son in her marehood, and she had absolutely no intention to. Incestuous sexual intercourse of that kind was a step too far and not something there was any need for.
She'd done just about anything else, though. It wasn't just about jerking Button off, and really it hadn't been for a while. There wasn't a part of her body she hadn't used to please him at some point, not a part of her body he hadn't coated in his pre and seed, and she could feel herself changing as a result. She knew it was happening at that point, with how her clothes didn't fit her properly anymore.
Her huge breasts had swollen rounder and bigger after all the times she'd had Button thrusting between them and cumming all over them. The same went for her fat ass, which Button liked to play with and stroke himself over. The former were now wider than her shoulders, and the latter wasn't far behind, jutting out rounded and scandalous when she stood. Her lips, after so much kissing and licking at his shaft and after she'd eaten his cum both by accident and willingly, had plumped into something rather obscene-looking that evoked the clear image of cock pillows and fellatio at just a glance.
Her mind was changing in tandem with her body. She could hardly think of anything other than sex those days, and in general she was far hornier on average than she should have reasonably been. Not that there was anything reasonable about their situation, all things considered, but even then she could feel herself slipping. She actively fantasised about her son. She would look forward to his return from school as she cleaned his messes around the house and washed his clothes of all the precum he drenched them in.
Button's return from school was always the most tense moment of the day. With no way to relieve himself while he was out in public, Button always arrived more pent up than ever. His cock throbbing, trying to free itself from the confines of his underwear and threatening to rip his pants apart, and his balls swollen and heavy with seed. He'd struggle to get home, take off his bottom clothes as soon as he was inside, and immediately beg his mother to help him get off. Something she would be more than eager to do every time.
She'd jerk his shaft, suck it, give him boobjobs with her massive tits, cradle his huge balls, let him rub against her fat ass, and all other manners of things. He'd cum, and he'd cum, and he'd cum again, unloading buckets' worth of his seed all over her. She could practically feel herself changing as a result, but she couldn't stop herself from doing it at that point. At first she'd told herself it was because her poor Button needed her help, but by then she had admitted to herself full well that she was into it. His cock and thoughts of it consumed her days and she loved every second she got to play with him. She'd even started drinking and lapping at the stains he left around the house, though she hadn't told him.
It did not help matters that Button's classmates were more than a little prone to teasing him for his condition. Fully aware that he couldn't just start jerking off in class, but also of the fact that he had to go to school to learn and for his mother to have time to look after the house instead of just after him, the other young adults never failed to try to drive Button wild while he was still in their company. Some days he had to come home early because he just couldn't hold himself anymore, and Miss Cheerilee of course allowed him to. Maybe it was the fact that he was the only one affected by the mutation in the whole school that drew so much teasing to him.
Three girls in particular were very active in getting him riled up at inappropriate times. Maybe they did it out of genuine interest in the colt, and maybe the didn't realise how bad it got for him. Regardless, they would tease him nonstop on some days.
That was one of those days. All through the day they would pet him, brush against him, throw him sultry glances of the kind only girls their age know how to throw, pat his bulge, 'accidentally' bump into him, tease him with implied promises, and kiss him on the cheeks and head and ears. It did not help that Button had a test he could not skip during the last hour of the day, and so was forced to endure them all day long. He did his test as best he could in his highly strained mental state, and rushed home as quickly as his bulge allowed him to afterwards.
When his mother saw him coming from the window she audibly gasped. She'd never seen him that pent up. His pants were actively ripping and she could tell his underwear had already broken. His balls were simply huge, far larger than even the basketballs he had in the courtyard to play with, closer to watermelons at that point and probably past it. His cock, already normally past the two feet mark, looked painfully swollen even while not fully hard yet, almost sore. Most of her was utterly mortified and worried. But a deep, quiet part of her was excited. She knew he would come oh so much.
The moment the door opened, Button didn't even wait until he was inside to kick off his ripped pants and ruined underwear, both heavily wet with his pre. "Muuum!" he whined, closing the door. His cock quickly swelled to full mast and throbbed obscenely, leaking a puddle on the floor.
His mother was to him in a moment. She knelt before him and stroked his cock with both hands, noting how she couldn't even fit the whole girth in them anymore. He leaked like a faucet, a deluge of precum flowing from his tip that coated her hands and wrists and arms and flowed down to his balls and the floor. He was panting and whining, his eyes watering. His mother gave his tip a kiss, coating her face in his juicy pre. "There. Mommy is here now. I'll make it all better." Already she was huffing up his musk, and her vision started to swim.
"Those three fillies were so lewd to me," Button lamented, leaning against the closed door as his cock leaked. "Apple Bloom kept touching me and petting my shoulders, and Sweetie Belle was giving me these looks and touching me with her hooves and her tail, and Scootaloo stroked her feathers under my chin and she whispered in my ears. It was so hard, Mommy. Hnnng!" His hips spasmed and his cock flexed, and a first huge drop of cum slid out of his tip.
"It's all good now, dear." Button's mother looked at the huge white drop as it rolled down his massive shaft. She couldn't help herself. It would end up on the floor otherwise, she told herself. She leaned forward, opened her mouth wide, and took the drop in. She swallowed it slowly, savouring its thick, creamy texture and powerful taste. It burned pleasantly down her throat and it made her head spin and her thoughts scatter.
Before she even realised it she was pumping her hands around his cock faster and wrapping her mouth around his tip. It was no easy task with how massive he'd grown, and she had to stretch her jaws to accommodate his size. As her mouth opened lewdly she swirled her tongue over the wide flat top of his dick, coaxing more precum out of him. Her hands slid frictionless over his whole impressive length, helped by the huge amount of pre he'd already leaked out.
It didn't take long for Button to cum. It never did. He wasn't quite a hair trigger, but his condition made cumming easy with the sheer amount of extra pleasure he experienced, and pent up as he was that was only made worse. Besides, he was actively trying to get off. He got almost as much pleasure by physically freeing out his balls from all the pent up seed as he did from the act of cumming itself.
When he did cum, a fountain of seed erupted from his tip. "Ooh, oh fuck!" he loudly moaned, throwing his head back as his knees went weak and shots began to flow up from his shaft and straight into his mother's mouth, and down into her gullet. She took it well, but even he could only take so much against his pent up climax. Soon cum was leaking out of her lips, and some even from her nose, while her belly swelled with her son's seed.
Swell it did. Maybe as a result of the magic changing her, or maybe as a result of how much Button came, but taking his loads in her mouth always left her belly swollen more than if she'd had too much food to eat, It wasn't painful, it was the opposite in fact, but it was noticeable. Her belly was stretched, her skin distended a bit like a balloon, her gut rounded and huge from the sheer quantity of seed she'd taken in.
Button wasn't done, though. Far from it. It didn't seem as though cumming had even particularly relieved him, as his balls were still monstrously swollen and his cock was still every bit as hard and huge and needy as before. His mother pulled back, rubbed the back of her hand over her lips to clean away some of the cum there, and went to work. Her son needed her, after all.
She took off her top, sliding it up over her arms and shoulders and tossing it aside. She wasn't wearing a bra underneath, as she didn't have one capable of housing her expanding chest, and so she didn't have to take off anything else and went straight for wrapping her tits around Button's cock. She pressed them into his shaft from both sides as her swollen belly pushed against his overfilled balls, engulfing his girth with her unnaturally big boobs, and began to stroke them up and down along his length.
Button was sliding down the door, dizzy from his orgasm and from the day of being pent up and from just how much blood maintaining his erection required. His mother stopped pleasing him for a moment, which did get him to whimper in protest, and took him in her arms.
He'd grown heavier ever since his cock and balls had started swelling, but his mother tried not to think about the sheer heft of his genitals as she carried him to the sofa and her nethers grew damp, a stain of arousal spreading on the crotch of her pants. She set Button down on the sofa, sitting, and immediately went back to her boobjob.
Perhaps because of how pent up he was, or perhaps as a reaction to all the stimulation he suddenly received all at once after moments of nothing touching his cock, Button came immediately. His hips flexed and thrashed wildly and he shot thick ropes of hot, heavy cum in the air, which all fell down over his mother's body.
She smiled at him, failing to hold herself back, and opened her mouth to catch what cum would land on her face while letting the rest fall on her. At least she'd removed her top, and her pants needed to be changed anyway. It was then that the smell of cum fully hit her, and her breath grew heavy as her thoughts slowed. Maybe it was how potent it had gotten as the mutation kept going, or how dense it had become after a day of being pent up, or maybe she just felt its effects more and more the more time passed. Regardless, it almost sent her feral.
It was a good thing then that Button still wasn't done, or anywhere close to it. Her nethers leaked out profusely and she redoubled her efforts to milk cum from his dick, rubbing her breasts up and down his length at a frenzied pace. His next orgasm came soon after, yet more white ropes landing over her that she didn't bother to even eat up. She was too focused on getting her son off, and while she did like his cum she could always get more right at the source.
She placed her mouth around the top of his dick and began to go down on it. Most likely as a result of exposure to the magic within him, her throat began to expand and stretch to accommodate his size. She went lower and lower, and while she didn't make it halfway it was still impressive considering his impossible girth and length and how she had not been able to do as much before.
She bobbed her head up and down, still using her breasts to please Button. Soon after he came once more, and his cock throbbed powerfully as cum swelled through it, shooting straight within his mother. She drank it eagerly, even as she failed to swallow it all and some flowed back out once she pulled herself off his tip. Her belly swelled even fuller, looking close to a pregnant one. But he was still hard.
Button's mother jerked him off, over and over, getting coated wholly in his cum. She offered him titjobs, and worshipped his length. She licked and kissed and stroked, and inside and outside she was drenched in his cum. Her belly was swollen and her skin was almost completely covered in white, sticky seed. Hours passed. But Button was never done. It was never enough. The pleasure he got from her servicing him kept him excited more than climaxes did to exhaust him, and he was almost as pent up as when they'd started even several orgasms later.
His mother was panting heavily. She was shuddering all over. Somewhere in her brain, she knew she needed a break, and to find a new approach to the situation. But everywhere she looked was cum. It was all she could see, all she could smell, all she could feel, all she could taste. All she could hear were Button's moans, and the sounds of his cock, and the sounds of his massive balls churning as they produced more and more cum.
And as she knelt there, after hours of servicing her son, so thoroughly immersed in sex and cum, something snapped inside her. As she heard him begging, saying he needed to cum, she lost herself. With animal movements she stood, pushed down her pants, and turned around on her knees so he could mount her. She was a bitch in heat, overwhelmed by her basest instincts, wanting nothing more than for him to breed her like cattle fucks.
Button looked down at his mother for a moment, and then he slid forward and lined himself up. He couldn't hold himself back, and he didn't even think about what he was doing. His dick was doing the thinking, and his dick wanted a warm wet place to slide inside of. It found it quickly, and his mother's sex began to part before his shaft. It was a tight fit, velvety and heated, better than her throat could ever be. It enveloped the tip of his dick, clamping down on it, and he started to push the rest in, far too eager to experience more of that wonderful sensation that was fucking his mother's pussy. It was practically a struggle, but every new bit he pushed in felt amazing and he could not stop himself.
As her sex began to be thoroughly filled and spread, Button's mother threw back her head and loudly moaned. It was like nothing she'd ever felt. She had no idea something so big could even fit there, having never tried, and while it wasn't quite fitting yet it was doing its best to. It required a lot of force, but it felt overwhelmingly pleasurable. Her cunt began to leak around her son's cock to ease him in, and his pre burned pleasurably against her inner walls. Inch by inch he slid inside her.
The magic within Button began to affect his mother more than it ever had before, now that his fluids could directly enter her through her pussy. She felt herself shaking from head to tail, overwhelmed by the physical sensation of magic entering her. Her eyes shot wide open, morphed into heart shapes as a reaction to the sudden influx of energy and to her current emotions. She didn't ask Button to get in deeper so much as let out a deep moan that vaguely implied her desire for him to do so.
Not that he needed to be told. Button, gripping his mother's wide hips and sinking his hands into her fat ass, started to pull himself forward and push his cock in more and more. He wanted, needed more of her. He had to be inside her with his shaft, all the way. So he pushed and pushed, feeling more of her velvety walls around his cock the deeper in he managed to go. She was overwhelmingly tight around him, but that just made it better, a strong pleasurable sensation unlike anything he'd ever felt.
His mother too felt incredibly good. Being stretched like that was simply driving her wild, sending her senses and brain into overdrive, making her practically feral with arousal and lust. She pushed her hips back, trying to meet Button's own push, desperate to get him sheathed all the way inside her.
And so much they both pushed that eventually, despite how tight her hole was, they succeeded. Button found himself bottoming out in his mother as, with a sudden forward lurch, the last few inches of his cock all slid forward into her. The sudden sensation of it, combined with how pent up he was, proved too much to take, and once more he began to cum.
His mother was already just about to climax from being so thoroughly filled all at once, and the first spurt of cum sealed the deal fully. She opened her mouth wide and screamed her orgasm as her nethers clenched and gushed and her arms almost gave out. Her nipples were stiff and her eyes rolled back and she barely managed to stay conscious as a tide of pleasure overwhelmed her.
Button's balls tensed up and he came and came, flooding her insides with his seed. Thick, heavy, hot and potent, white loads one after the other began to bloat her belly. She'd already had a huge gut from swallowing his cum, but what she had at that point made her look heavily pregnant, and then some. Button's orgasm did not cease and his mother's body only encouraged it, squirming and writhing as if trying to milk more pleasure and seed out of him. He barely managed to stay up himself, completely entranced by his own climax, with his eyes rolling back and his open mouth drooling.
He came and came, until finally his orgasm subsided. He was nowhere near done though. His cock was still hard and aching for another climax, his balls were still full and heavy, and he still craved release. Moreover, he craved more of the wonderful new sensation he had discovered. For her side, his mother was still in the throes of passion, and craving more of him as well.
So they kept at it. For minutes, then hours, Button kept breeding his mother's sex with feverish intensity, and she kept egging him on with frenzied lust. Her pregnancy was all but assured after merely the first load, but she couldn't care less in her state. In fact, it only excited her further. Having her son fuck her like that had awakened something primal in her, let her brain be overwhelmed by a base lust for breeding and carrying someone's spawn. It didn't matter that that someone was her own child. The sheer strength of his virility was simply too great for her not to embrace it.
And it only grew greater. Even as they fucked, Button's cock seemed to lengthen and swell, and his balls looked like they were growing larger and heavier too. Of course they were too preoccupied with fucking to notice any of it, but any outside observer would have seen it clearly. It was as if the act of sex itself had unlocked a further stage of Button's mutation, and he was suddenly growing at an accelerated rate.
He wasn't the only one, either. His mother's body had already been growing to go along with his, but as she embraced her role as his broodmare that growth too became far quicker and more pronounced. Her tits and her ass swelled huge, her hips widened, and her thighs thickened. She looked fit for nothing other than breeding, and her belly grew and grew with his massive loads.
By the end of the day, when Button was finally sufficiently spent, the room was a mess and the two of them barely looked like they had before. While most of Button was still the same, his cock and balls had grown significantly in size, double what they'd been the previous day, to the point where sliding them out of his mother's thoroughly used pussy was a bit of a struggle, not helped by how her walls greedily clamped down on his length, begging for more.
His mother had been thoroughly transformed, though. All the sudden direct influx of magically irradiated fluid had shaped her as if she was afflicted by a minor case of the mutation herself. Her tits were simply massive and already her huge, hard nipples were beaded with milk. Her ass was so fat one could sink in it. Her wide hips looked designed for bearing and birthing foals. And her belly, so filled up with cum from both ends, made her look more than ready to give birth already. She was panting, her eyes two heart shapes, her body covered in sweat and in her son's cum. And still she craved more, completely overwhelmed by her new mental state as his broodmare.
When morning came the next day, Button's mother found herself filled with a strange sense of clarity and acceptance. And a lot of cum, of course. She was on the floor, with Button's cock still halfway inside her. She knew for a fact she had to be pregnant with his child, even judging by how full she still was. She knew she should have been worried, and that common sense dictate she react a certain way to what had happened. Yet she could not bring herself to care about any of that, about the propriety of any of it. All she could care about was thinking of how things would get from there on out, and wondering just how much more her body and Button's would grow.
Sex became a regular occurrence after that day. No longer a taboo act, now merely another one of the many ways she could go about pleasing her son and relieving him from his painful condition. It was just as well that she'd started to do so, because Button kept getting more and more pent up through the days, only growing bigger as time passed. His balls were past the point of being comparable to any kind of fruit, closer to huge exercise balls and impossible to hide. Thankfully school was closed during the summer, which allowed him to stay home without needing to be confined by too small clothes.
His mother wasn't quite so fortunate, since she still needed to go out for buying groceries and whatever else the house needed. She could feel the stares of everypony in town on her, and she couldn't blame her with the way her body had grown. Her tits were massive and already she could fell them filling up with milk, her hips were wide and they swayed with her every step, and her belly was always bloated to bursting by both the growing pregnancy and the sheer amount of cum she took daily in all her holes. She suspected she had twins, with how large she was.
Not that she wholly disliked the attention though. There was a certain thrill that came with it, a modicum of excitement from being clearly exposed as a fertile mother and even from knowing it was clear who the father of the newly growing life inside her was. Button's condition, impossible to hide as it was, was no secret across Ponyville. His mother could hear the whispers trailing behind her about her fucking her son. They just excited her. Those other ponies had no idea how amazing her little Button was.
His cock had grown significantly since they'd started fucking. It was near double the length it had been, and it was only thanks to her own intake of his magical fluids that his mother still managed to take him. She was always tight and he was always huge, but he wasn't too big and she wasn't too tight, so things worked out. And oh if they worked out. They would go at it nonstop for hours. Her pussy was definitely Button's favourite hole of hers, even if he still enjoyed boobjobs and oral and all other manners of activities between the two of them.
The house was always left a mess after they fucked. That meant it was Button's mother's duty to clean up, while Button himself recovered. She'd do so in the nude, because clothes would just get dirty and because so few of them still fit her growing proportions. Inevitably, the sight would get Button aroused again, and soon the cycle would repeat, over and over until she had to leave or until it was time to eat or sleep. Though they were both eating less and less regular food, as she was eating up copious amounts of her son's spunk and he had started to drink the milk that already was starting to leak from her massive breasts.
It was a few months into this cycle, on a particularly hot summer day, that the two of them began to notice something unusual. Something about Button's mother, and in particular her belly. It was always swollen, of course, but lately it had started to look bigger than usual. It was morning when they noticed, when it should have been at its smallest before it was pumped full during the day. Initially they thought nothing of it, but they kept it in mind. But in the following days the swelling seemed to still be there, and becoming more noticeable, faster than just her known pregnancy should have justified even had she had triplets in her. So, when they eventually managed to get themselves in a state where they wouldn't constantly be fucking, they went for a checkup.
The news came as a bit of a shock, though apparently it wasn't something unheard of. The doctor was very understanding, evidently one knowledgeable in such cases, and he didn't comment on the state of their relationship. He just delivered the results, professionally explaining what exactly was going on.
As a result of Button's magically radiating seed, his mother's pregnancy had mutated into something different. Or, to be more precise, her single pregnancy had become of a set of multiple different overlapping pregnancies.
It was apparently perfectly safe, both for her and for her many children. Her body had started and would continue to magically mutate to accommodate all the new life blooming inside her. Her chest and hips would swell even further to sustain all of it, and her belly would continue to grow. So long as Button kept breeding her, she'd keep growing more pregnant, until she started to give birth and stabilised at a consistent maximum size. Assuming the rate at which she was bred was consistent, of course. She'd effectively turn into a full time broodmother for her son's children.
Button had seemed strangely excited by the news. It was like the prospect of her bearing his spawn actively turned him on, and the idea that he could keep breeding her nonstop seemed particularly arousing to him. His cock had hardened right there, slightly ripping the fabric of the special pants he'd worn for his trip out.
His mother had taken it differently. Less overtly excitedly. But she wasn't put off by it either. It was strange. She guessed she needed some time to think things through, and she'd said as much. Unfortunately for her, that didn't quite prove to be a possibility. Thinking about things wasn't really in the cards for her in her state. Not when, as soon as they got back home, her overeager son began to breed her anew.
She couldn't say no to it or to him. She craved his cock and cum far too much. As soon as he dropped his pants and pulled out his shaft, all her thoughts and worries went out the window. There was only the present, the sex, the base need to be bred. By that evening, Button's mother wasn't so averse to the idea of having multiple simultaneous pregnancies, especially not if it meant being fucked as hard as Button had fucked her that day for the rest of her days.
So, time passed, and the signs of her multiple overlapping pregnancies became impossible to miss. Firstly, and obviously, her belly swelled larger than it ever previously had. Even when it wasn't bloated full of cum from one end or the other, it was impossibly big, jutting obscenely forward and sideways, rounded and dotted with bumps from the many pregnancies in various states of development she was filled with. Between that and the way the rest of her body changed, moving around was starting to become an inconvenience in itself.
To start with, she had to actively squeeze her way through most doors, and soon that would be all of them barring double doors. None of her clothes fit anymore, and she grew at such an alarming rate that she couldn't even buy any. They would all turn out to be too small in just a couple of days. She'd taken to wearing huge uncut swats of cloth around her bust and her legs, a bit like rough togas, though that had its own set of problems.
For one, her tits. They were leaking milk, and not just when pressed or suckled. The combined pregnancies led her chest to swelling, full of milk, so much that she actively heard it sloshing around her overfilled boobs when she moved. It was a painful kind of pressure that made her understand in part what her little Button must have been going through down there, though his balls' production was greater even than her breasts'. It was a good thing that her son liked to nurse on her tits, as it helped relieve some of the pressure building up inside them.
That still meant they would absolutely drench her clothes whenever she was wearing any, leaving the cloth on her bosom practically transparent and only intensifying the amount of stares and whispers directed at her when she went outside on some errands. It also made cleaning the house even more of a hassle, and given how she did so on her knees with her fat ass wiggling that always led to even more of Button breeding her.
She'd thought about getting a maid to help keep the place clean. It was a real possibility, and money wasn't a problem. She was worried about something else though. Not that she'd admit it, but she didn't trust that another mare in their house wouldn't end up like she had. Overtaken by the musk of Button's overwhelming magical virility, and soon sucking on his cock like his mother. She was, even if she refused to say it, a little jealous of her little colt. She enjoyed having him all for herself.
That was most likely why she wiggled her hips at him in the fist place when she was around the house. She was hoping to get a reaction out of him, and she loved getting one. And he loved looking at her, by all means. Especially those hips and ass of hers, and especially with how huge they'd gotten. The former had widened even farther to properly carry the full weight of her multiple pregnancies, and the latter was a match for her enormous tits, a pair of huge and soft asscheek pillows that served as cushions wherever she chose to sit.
Then there were also the changes that were more subtle, if anything cold be subtle about her state, or at least less immediately visible. The mental ones, and the physical ones that weren't as hugely apparent as what had happened to her tits or ass or belly. The former in particular were having a huge influence on her, on her way of living and day to day experiences.
She'd embraced her role as Button's breeding broodmother, but it went beyond a simple acknowledgment that she was as much. It actively shaped her mind and what her thoughts drifted to. More and more she was finding herself thinking about his cock and cum and sex when she wasn't actively partaking in any of them, and even her dreams were shaped around their sexual intercourse and her growing multipregnancy.
The pregnancies too had taken a different look in her mind. The knowledge of them and the feeling of all the subtle and big changes they brought excited her, and made her feel fulfilled in new, amazing ways. She was coming to love her future incestuous children just as she loved their father, and moreover she was loving the act and feeling itself of being pregnant. It hadn't been like that when she'd been pregnant with Button, but then she hadn't been nearly as full or heavy with him.
Goodness was she full and heavy. Moving itself was becoming an act that reminded her of her condition, and with that reminder came happiness and excitement and lust and a craving for more. More sex, more cum, more pregnancies to add to her swollen belly. More of her son's massive, gargantuan cock stretching her pussy and pumping litres of cum inside her womb.
The same went for any attempts she made at exercising. She had to keep in shape after all, yet doing it was a bit of a struggle when every slight bend or yoga pose became near impossible in the face of her newfound proportions. At all times she was constantly reminded of how her life was changing. Every facet of her daily activities was being altered and reshaped around the status as broodmother she had started to develop into.
And yet, despite everything, she was happy. More than happy. She was excited. She actively loved her new condition. It was the best feeling she'd ever experienced, all things considered. The constant feeling of fullness, the constant sensation of arousal, it was all amazing. She was always horny, always looking forward to the next moment of sex, always leaking from her wet cunt. And when the sex did happen, it was amazing.
She was addicted to it. She was addicted to Button, and his cock, and his cum. With how much he'd grown, she couldn't help but be completely enthralled by it. His cock was simply massive, and his cum production had grown exponentially. She was addicted to sniffing his musk, to inhaling his scent, to licking his balls, to drinking his cum, to having him use her every hole to get himself off.
More and more time during her days was spent servicing and pleasing Button and helping him get off. She couldn't help herself. It was just too amazing not to, and he needed it. He needed her, and she needed him. It was all too great. The taste and the smell and the sheer virility he exuded. She would have spent her entire life with his dick in one of her holes if she could have done it.
As it was, she still went pretty close to it. Her and Button would fuck for hours, multiple times a day and often even at night. She was already considering homeschooling him going forward, since it would let her keep him close to himself. Part of her thought that was just a way to make sure she was always available for him to relieve himself, but another knew they'd just end up fucking all the time and ignoring his studies.
Was it really so bad though? Surely with Button's conditions and her own the government might help, as they did with other such cases. Then she could fully devote herself to her son's needs, without any need to go outside and stay away from him. Besides, she would need a lot more time soon, as she'd start to have to worry about both Button himself and all his kids.
That knowledge worried her a little, when she wasn't fully drunk on sex and cum. She wasn't going to give up on her role as broodmother and breeding mare for Button, of course. He needed her, and she wanted him. But would she have time to both look after him and look after all their kids once they started coming? On one hand they would help relieve the pressure in her chest, which was only growing, but on the other she worried about splitting attention between the two tasks.
Thankfully, it was Button himself that ended up coming up with a solution to her potential problem. It was a hot day of late summer, and the two of them were partaking in their favourite pastime. The table was empty despite it being lunchtime, and they were in the living room, eating their meals from each other instead.
Button's mother, lying on her back, had her son's titanic cock stuffing her throat, with her hands on his gargantuan balls, massaging them as if to coax more cum out of them. Button was on top of her gigantic tits, greedily sucking on one of her nipples and drinking up her milk. He lazily shifted his hips, getting a bit more of his cock into his mother's throat. Beside him, her other nipple leaked by itself, spilling milk down her cleavage.
He pulled his mouth off of her nipple with a pop, as his balls tensed under his mother's ministrations, ready to unleash another deluge of cum into her gullet. "Mommy?" he called out, before biting his lip to stave off his orgasm a bit longer.
His mother answered his call. It was unclear what she answered with, as the words came through gargled and messy as vibrations around his shaft. That led him to finally snapping and cumming, flooding her throat and belly with thick white seed that bloated her up even more. It took a while for him to stop, and by the time he was done her face was covered in his spunk.
Finally he pulled his cock out of her mouth and moved to her other end. "I was thinking, you know, this is nice and all, but could I invite some friends over? I think it would be nice to play with them too. Those three fillies I told you about, Apple Bloom and her friends, would that be okay with you?"
And Button's mother thought it was the perfect solution to her problems, as it would allow her to look after her kids while someone else looked after her first son. Then he speared his mammoth shaft in her tight pussy, and all she could think about was sex and cum.
