Sandy Surplus observed herself in the mirror with a mixed expression. She had a body that most mares idealized. She was very trim and well proportioned, with hardly any unnecessary fat anywhere on her body. Topped off with her almost golden fur, light brown mane, and yellow eyes she considered herself pretty lucky in terms of appearance. By the standards of most, her figure was perfect.
“And here I am thinking about ruining it”
Surplus always faced an inner conflict. While she had worked hard to stay fit and maintain her idealistic image, she had always suppressed an embarrassing kink within herself. Ever since her puberty days, she harbored a strange fascination for ponies who were larger. On many nights she wondered or even fantasized what it would be like to have a large, drooping belly. Or how it would feel to possess a massive flank that bounced and jiggled with any movement.
Despite how intense her fantasies could sometimes get, she was never willing to take on the risks that gaining weight would involve. After all, if she sacrificed her current figure it could be nearly impossible to get it back. That’s when she discovered something that at first seemed too good to be true…
While browsing materials distributed by a group of ponies with similar “unusual interests” as hers, she found talk of a spell that might just let her explore her fantasies without too much risk. According to what she read, said spell would allow a mare to rapidly gain weight for just a temporary time. Any weight gained through this spell would wear off after 24 hours so long as the magic wasn’t reactivated. There was a pretty big catch though. The method this spell used to add weight required…
Cum digestion
According to the magazine article, the spell allowed mares to absorb the semen of colts and somehow turn it into fat. It didn’t have to be just consumed by mouth either, anywhere in the body would have the same effect. Normally, this would have been the end of the road for that idea. However, she happened to still know a couple of old friends from high school who might just be crazy enough to help her go along with this. They were twin brothers, named Dell and Dane. They had always had a passing interest in larger mares, and she’d seen both of them do a fair bit of sleeping around. So she gave them a call and invited them over. However, she still had no idea how she’d explain this insane idea of hers.
“Asking two guys to sleep with me, and to pump me up into a fat mare while they’re at. This doesn’t just make me sound like a slut, it makes me sound like a crazy slut”
There was no shortage of doubts in her mind, but she resolved to push them aside. Besides, it was just one night. Not like she was going to go overboard or anything.
It was a few hours later when the brothers arrived. Sandy quickly finished brushing her mane and made her way to the door to greet the two. Standing before her were two colts with the same broad frame, dark blue fur, and orange eyes. The only way to differentiate between the twins was the slight differences in their cutie marks. Both cutie marks featured a map with an arrow on it, Dell’s pointed right and Dane’s pointed left. Or, at least, she thought that was how it went.
“Hey, you two! Thanks for coming. I’ve got an interesting idea in store for us.”
The two brothers traded looks before following Sandy inside.
“You did sound awfully excited over the phone,” said Dell, “What’s this idea of yours?”
Sandy bit her lip, trying to think how to explain her idea, “Well, you see...I recently came across this thing...and I know you two are always up for a bit of experimenting...and..uh, fuck it, just look at this,” she finally gave up on trying to explain and just gave them the magazine.
Dane quickly snatched it, with his brother reading over his shoulder. The emotions on their face varied from confusion, to shock, to growing interest. They both blushed heavily as Dale put the magazine down.
“So, you want to use that spell? And you want us to be the ones who facilitate it?”
Sandy nodded while blushing heavily, “I know it’s a lot to ask...but it could be really fun for all of us. What do you think?”
Dane and Dell whispered to each other for a couple very uncomfortable minutes before turning back to Sandy.
“Well..” Dell said, “It is a pretty strange thing you want to do here…”
“But we’re willing to give it a try,” finished Dane, “The problem is, I don’t think even the two of us combined will be able to produce enough for you to really get much out of that spell”
“Oh, that won’t be a problem!” Sandy replied, “I have another spell that can give you both a boost. In fact, we should be able to go as far as we want with this.”
The twins smiled at each other and back at her, “Let’s do it then”
“Great!” she exclaimed, feeling her heartbeat going up with excitement. She still couldn’t believe this was about to happen. She only hoped it actually worked, “Just let me get myself ready, and then I’ll get you ready too~”
She brought out the book where she wrote down the details of all the spells she knew before charging up her horn with energy. She carefully cast the advertised spell on her body, it gave her a slight shiver but other than that she felt about the same afterward. She also cast a second spell on herself that would nullify any of the negative health consequences that a rapid increase of weight might cause. She then turned back to her partners in crime.
“Alright, boys, get ready. This might feel a bit overwhelming at first.”
Dell waved a hoof dismissively, “Oh please, I doubt we’ll even not-ooooh.”
Sandy smirked with knowing excitement as she began using magic to enhance the sperm production of both brothers, swelling up their balls in the process. Both the stallions in front of her blushed heavily as they felt the weights in their scrotums steadily increase. Each of them soon found themselves with a pair of nuts the size of baseballs and still growing. They groaned heavily, their legs shaking as Sandy’s magic continued to work on them. The two were soon spreading their legs to make room as their balls swelled larger and larger with each passing moment. When the spell was finally done each brother had testicles roughly the size of basketballs, audibly sloshing with the sheer amount of sperm inside whenever they made the slightest movement.
“Well, how do you feel?” Asked Sandy in a sultry tone.
Her partners seemed to struggle to even find words, being so overwhelmed with the arousal and need of their swollen gonads. “S-So full...can we get started? I really need to..” Dane pleaded, with his brother nodding.
“No need to ask. Just get over here and we’ll get to work~”
The two stallions wasted no time accepting Sandy’s invitation. Dane took up position behind her while Dell walked over to the front. Dell stood up on his hind legs and balanced himself against the wall before allowing his stiff member and over-sized balls to flop right down into Sandy’s face.
Sandy blushed heavily as she sized up the equipment in front of her. Dell’s member stuck out proudly with both length and girth, with heavy drops of pre-cum already dribbling out. Below that were his massive testicles, each sloshing heavily with the fluid she so desired. It aroused her, even more, to know that it wasn’t just cum within those balls, what they contained was, in essence, a growth serum that would allow her to grow beyond her wildest fantasies. She eagerly shoved her face into his crotch, allowing his powerful masculine musk to assault her senses and excite her further. Her tongue moved from her mouth and began to slowly lick the member in front of her. Dell let out a light moan as his member throbbed lightly in response.
While Sandy worked to get Dell lubricated, Dane was getting himself ready on the other end. He began to grind his hard shaft against Sandy’s dripping wet marehood while gripping tightly at her hips. At the moment her flank was nearly flat and her hips only had the barest of curves, but he excited himself with the knowledge that was all about to change. His arousal only increased as he imagined her flanks and hips starting to balloon out with extra weight. Soon every bit of cum they pumped into her would add more bounce and jiggle to her body.
“I don’t know how long I can restrain myself, you two love-birds almost ready?” Asked Dane.
Dell groaned heavily, being somewhat overwhelmed by the way Sandy eagerly licked all over his genitals, “Y-Yeah..I’m ready. S-Sandy?”
Sandy smirked up at him, “I’m ready, boys. Don’t hold back,” she then took a deep breath before taking the head of Dell’s member into her mouth and began lightly sucking on it. A quick few seconds later she felt pressure being put on the lips of her marehood, and a second after that Dane’s member began to force its way inside her inner walls. She let out a muffled moan of pleasure as she felt his shaft slowly pushing deep into her marehood. Both stallions penetrating her moaned lightly with pleasure as they started to gently thrust their hips back and forth. Sandy found more and more of Dell’s cock being pushed into her mouth, while Dane began to pound her marehood at a steady rate.
Sandy was in heaven. On both sides of her were attractive, well-endowed stallions eagerly using her body. All the while she could hear the heavy sloshing of their overfilled testicles. There was so much seed ready to be pumped into her, ready to swell her body up to the plus sizes and beyond. She did all she could to facilitate the process, sucking hard on Dell’s rod and pushing down her gag reflex in order to take him as deep into her mouth and throat as she could manage.
“Holy crap, she really does want this,” remarked Dell as Sandy’s surprising vigor began to take a toll on his resistance, “I don’t know how long I’ll be able to hold it if she keeps up like this.”
“Then let’s give her what she’s waiting for!” Dane’s exclamation was emphasized by the sudden increase in his tempo. He began ruthlessly pounding away at Sandy’s marehood, with his heavy balls roughly smacking against the back of her legs as well. Dell followed suit by gently grabbing hold of Sandy’s head and thrusting in and out of her mouth, practically face fucking her. She could do nothing but continue to let out muffled moans as the two brothers began to roughly use her from both ends. She could tell both of them were close by the intensity of their groaning and the way their cocks were throbbing harder and harder. They were about to cum hard, and it was going to be a wild ride for her.
It was Dell who released the first tidal wave. He let out a shameless moan as he began to pump giant, thick streams of seed into Sandy’s throat. Sandy worked hard to suppress her gag reflex as she challenged herself to swallow the nearly overwhelming amount of splooge being forced into her. Her belly soon began to fill up as she forced down wave after wave of Dell’s seed. She was determined to get as much as she could though as she lightly massaged the stallion’s balls with one hoof, making him orgasm even further.
Next was Dane’s turn. The other stallion slammed into her marehood hard before releasing his own tidal wave of semen. Each thrust of his hips added to the ocean of seed already filling her womb. Within just a few moments her womb was full and began to swell slightly, with some of the seed spilling back out into her marehood. The double assault on her body was causing her belly to noticeably swell on the outside. First, a little pounce formed, and then it began to take on a round shape as her two partners continued to inflate her with excessive amounts of their sperm. Their production seemed endless, and Sandy was beginning to worry it might never end. However, after a final few thrusts, the two pulled out from both sides. They leaned back and panted while Sandy collapsed in an exhausted heap and breathed heavily.
“Oh gosh...you two, that was...that was almost too much. I feel so bloated…”
“Well, it’s what you wanted isn’t it?” Replied Dane with a smirk.
“Ugh, yeah...you’re right. I just wonder when the spell will..” She was cut off by a strange tingling sensation inside of her stomach and womb. Suddenly she noticed her swollen pouch beginning to slowly recede. At the same time that her middle shrunk, other parts of her began to grow outward. Her previously flat, shapeless flank began to plump up and take shape. It was slow initially, with just a small layer of fat added at first. However, it only continued to grow as her body digested more of the cum inside of her. Soon her flanks began to take shape and round out, becoming both bigger and wider as her backside expanded behind her and to the sides. Her thighs were thickening, growing closer together by the moment. Her body was clearly taking a bottom heavy persuasion, but she could still feel a slight amount of fat being added to her face and front legs as well. She couldn’t help but moan at the sensation of so much new flesh being added to her body at such a rapid place. She began to rub her hooves all over her body, enjoying the sensitive expansion of her figure. Dell and Dane looked noticeably aroused as well, watching with intense fascination as Sandy gained dozens of pounds in just a few short moments. Just whenever everyone was wondering how big she was going to get, Sandy’s belly stopped shrinking. It wasn’t quite back to normal size though. Her once trim middle now had a squishy belly with a slightly rounded shape to it. She wasn’t fully fat by some definitions, but could definitely be called “chubby” by most.
“Uh...how do you feel, Sandy?” Asked Dell.
Sandy slowly stood up, working to adjust her balance due to how much heavier her body was, “It’s..it’s different, but..not bad.” She walked over and examined herself in the mirror, totally in shock at how different she looked. She was no longer some stick mare, she was a girl with curves. Any movement would cause slight movement in her squishy belly, or cause her plump flank to jiggle enticingly.
“Gotta say, you’re looking quite good,” said Dane.
“Well, thank you,” replied Sandy as she turned around and smiled at him, “But let me guess, you’re both thinking about making me even bigger?”
“The thought’s crossed our minds,” replied Dale.
“Hmm..well, the two of you almost overwhelmed me last time. But...I suppose we can go another round. No using my mouth this time though, a mare’s gotta breathe.”
“We can take turns,” replied Dane with a mischievous smile, “But...you gotta let whichever one of us is sitting out do some recording. We know you don’t plan on staying big, so we want to capture the memory.”
Sandy blushed heavily at the thought of this debauchery being recorded, but she did feel a certain thrill as well, “F-Fine, but personal use only. If you leak it to anypony, I’ll find you..and it won’t be pretty.”
“Dane and I will consider it a family secret,” replied Dell as he began pulling out a camera to record what was about to come next, “I’ll record first.”
“Alright, then. Now just get comfortable for this next part,” Sandy said before pushing Dane down into a sitting position. She charged up the same spell she used before, but part a lot more power into it this time. Dane groaned as his balls started to swell up once again, quickly filling up with gallons of sperms and growing outward. They soon reached the size of basketballs and continued swelling beyond even that. He spread his legs as wide as possible to make room as he watched his testicles expand to the size of two beach balls before finally stopping.
“Geez, Sandy, “Dane panted, “I don’t think I can even get up like this”
Sandy smirked, “Don’t worry, I’ll take good care of that little problem~” She then turned around and positioned her chubby flank above Dane’s member. She then began to slowly lower herself down until she felt the stallion’s cock beginning to part the lips of her marehood. A long moan escaped her lips as she continued to lower her body down, eagerly taking every inch of girth inside her. The arousal she felt was heightened at the size of the massive balls attached to the member she was riding. The growth spurt she’d receive this time would easily dwarf the one before. It was all the motivation she needed to begin riding Dane’s member hard and fast. Although she found herself panting with the effort not long after, the extra weight already beginning to slow her down a bit.
“Nnngh..yes..that’s it, Sandy...ooh I need to cum so bad...y-you getting this, Dell?”
Dell nodded, “Every beautiful moment” Dell positioned himself in the perfect spot where he was able to hold the camera with one hoof and began stroking himself with the other. It was an amazing sight to see Sandy wildly riding his brother’s cock, desperately trying to get the cum that would make her even bigger. Already she had put on such delicious curves, evidenced by the way her flank jiggled and bounced each time she slammed down on Dane’s cock.
“Ugh.Sandy...I don’t think I can hold out long this time,” Dane’s warning was emphasized by the heavy sloshing of the gallons of sperm in his balls.
“G-Good, I’m ready!” Sandy moaned out as she hit her own orgasm, her female juices drenching both the crotch of her and her partner.
Dell smirked with excitement,”Fill her up good, brother. She’s gonna be a big mare in no time.”
Sandy panted heavily as she continued bouncing on top of Dane’s member, panting with exhaustion before finally slamming down one final time. At the same moment, Dane wrapped his hooves around her squishy hips and held her in place as he began releasing a flood of seed into her marehood and womb. Just the first wave managed to fill her up to the point that she began to swell, and the deluge was only beginning. Dane repeatedly lifted Sandy up just to pull her back down onto his member, pumping out fluid like a firehouse each time. Sandy could only moan at the overwhelming sensation as her belly began to fill up like a taut water balloon. Her skin stretched tighter and tighter as her gut became a basketball, and then a beach ball. She began to worry her body might not hold up, but relief came as Dane’s load began to subside and she was able to slip off of his member. She collapsed to the ground in a panting heap, idly rubbing a belly that had been swollen up larger than the rest of her body.
“S-So much..but it feels so good..”
Dell smiled at her, “You think it feels good now? Wait until that spell of yours kicks in again. You’re going to be absolutely huge in a few minutes”
A few seconds passed, but then Sandy could feel a familiar tingling in her stomach. Only this time the sensation was much stronger, “I-It’s happening...I can feel it”. Ever so slowly her swollen belly began to recede, and her body began to send the newly acquired mass all over her figure. Her flank cheeks were swelling out at a steady pace, becoming heavier and squishier by the second. The sand dunes that comprised her cutie marks began to stretch out larger as her flank cheeks became more expansive, reaching over twice their previous size. Her thighs were getting ever so thicker, and soon she felt them rubbing against each other. While her belly was shrinking slowly from the loss of cum, she could feel heavy deposits of fat being added at the same time. Her face wasn’t spared from the assault, Sandy could feel her cheeks puffing up with extra bits of fat underneath. At the same time, she developed a double chin with the threat of a triple underneath. With the addition of a bit of fat on her back, no part of her was left spared from the extra weight.
The two brothers looked in shock and amazement at how much the mare in front of them had just grown. She might have been chubby before, but now she was an absolute pig of a mare. They watched with growing amusement as she struggled to stand with the heavier weight. Once she got up she began waddling towards the mirror again, all the while her massive flank cheeks jiggled and bounced behind her.
Sandy was incredibly intrigued by what she saw staring back at her. The mare in front of her seemed so foreign, only resembling her old form in just a few basic ways. She had to weigh over 300 pounds at this point. It was impossible to resist the urge to explore this new body, and soon she began to rub over her squishy gut with both hooves. It was a true belly, one that was jiggly, round, and drooped down slightly past her knees.
“Goodness, you boys have done some work on me,” Sandy said with a smile before teasing them by shaking her flank. She was amazed at the sensation of all the flesh on her backside jiggling and wobbling so madly.
Both brothers approached her, with Dell lightly sinking his hooves into her fat gut while Dale gave her a hard spank on the rear.
“You’re looking really good, Sandy, but what would you say to one more round?” Dell asked, “After all, I haven’t gotten to take you one-on-one yet.”
Sandy bit her lip, “Oh my...I’m already so huge, if we do that again..I might not even be able to move afterward. But, it would only be fair. And besides, it’ll all be back to normal in the morning anyways.”
“That’s the spirit, let’s get ready for the final round.”
A few moments later Sandy found herself braced against the wall with Dell aggressively ramming into her marehood over and over again. He was packing the biggest load yet, with his balls so large they grazed against the ground. Sandy could feel her entire body shake and wobble with every impact. Each time Dell’s hips thrust forward they’d create a tidal wave of jiggle which started in Sandy’s flank and traveled all the way to her massive gut.
Dell reached around to both sides of Sandy’s massive rear and was just able to grab both cutie marks. He eagerly rubbed and groped all over her beautiful, plump flank. Her soft flesh easily squished and molded as his hooves pushed in and around. Never in his life had he gotten to plow an ass this fat, and to think it was about to become even bigger. He smirked at the mental image of Sandy getting her over-sized flank cheeks stuck in a doorway and having to have someone shove them through like giant beanbag chairs.
“Wow, brother. Just look at her body move,” Dane remarked as he continued recording, zooming the camera in on the non-stop bouncing of her plot before also getting some film time of her giant belly jiggling like a jello-filled pool.
Dell groaned with pleasure, “I know. She’s so soft and bouncy and loves it too. Isn’t that right, Sandy?” Dell smirked as he gave her a hard spank to the cutie mark, making the entire right flank cheek ripple like waves on an ocean.
Sandy gasped and blushed heavily. The entire situation was both embarrassing but oddly arousing. The way they teased her, how they roughly groped and smacked the softer parts of her body, how nearly every part of her seemed to move in some fashion. She panted heavily with effort as she worked to push her hips back against her rutting partner, intensifying every collision of their hips.
Dell increased his pace even further, ramming into Sandy’s soaking marehood as hard and fast as he could. The only thing that could compete with the sound of her moans was the lewd slapping of flesh. He tightly held onto her both sides of her soft rear and groaned as he could feel his balls beginning to churn, “Almost there, Sandy. Get ready”
“S-So ready…” Sandy moaned and panted like a mare in heat, utterly overwhelmed by all the sensations. The bouncing and jiggling of her belly and flank kept her constantly aroused. In addition, hearing the constant sloshing of her partner’s vast load kept her mind filled with pictures of how unabashedly massive she was about to get. She pushed her hips back as hard as she could, her flank visibly bouncing right off of him as she did so. The force and weight of her backside were almost enough to knock Dell off balance, but he managed to hold on.
“Whoa, almost knocked me over you crazy slut. Alright, you want it so bad? Time.to.take it!”
A final set of moans was heard from both Dell and Sandy as each of them hit their orgasm. Sandy’s feminine juices lubricated the way for Dell to slam deep into her tunnel and begin pumping his seed out of his cock like a firehose. Entire pints worth of seed were released with every spurt, and minor thrusts on his part allowed a steady flow to leak into Sandy’s womb continuously. She panted with pleasure as the fulfilling warmth begin to fill her once again. She was now big enough that for a could while no swelling was visible, but with the dozens of gallons inside Dell’s testicles it was only a matter of time before her body began to inflate again. It was barely noticeable at first, but soon the bounds of her belly began to expand once again. Her massive gut became even bigger and wider as it advanced towards the ground. She shivered slightly as a moment after she could feel her flesh grazing the floor, and all the while Dell was eagerly pumping more of his fluid into her. By how big his balls still were, Sandy could guess that her partner was only about halfway done with her. The onslaught continued, and before long Sandy found her belly squishing outward and spreading against the floor. It soon became impossible for her to keep her hooves planted as her belly started raising up the rest of her body. Dell had to readjust himself and hold on tight to stay hilted inside of Sandy’s marehood, but managed to pull it off. His thrusts only became more excited as she noticed how big Sandy was getting.
Sandy could only lay there prone as she continued to get pumped fuller and fuller. She began to wonder if Dell’s orgasm would ever end. By the time it finally did, she had no hope of really moving. She had both of the stallions help roll her over onto her back and panted with exhaustion. Her massive gut towered above the rest of her by multiple feet, it was beyond the point where she couldn’t even see her belly button anymore. She attempted to massage her overly swollen gut with both hooves, but could only reach about halfway up the sides of her massive dome.
“Ughghh...so swollen...it hurts”
Dane looked down at her with sympathy, giving a light smile, “Don’t worry, Sandy. The spell will kick in soon, that should take the pain away. Although I don’t think you’ll be able to move again until morning.”
Sandy nodded just as she could feel the massive tingling in her belly.
“Uh-oh, here we go” She gave a slight gulp as her body started to absorb the insane amount of cum inside of her. Afterward, her body quickly began to balloon in all directions. Her flank cheeks billowed outwards, spreading across the floor beneath her. They quickly reached the size of yoga balls and were swelling even beyond that. Her cutie marks were at least four times their size by this point, stretched out proudly as her plot became billboards for them. Even her belly somehow managed to become even larger. Sandy could only watch with arousal and fascination as her belly steadily rose like dough, the mountain of her gut becoming even more extensive. Her thighs thickened to such an extent that walking would be impossible even if her belly hadn’t immobilized her. Her face thickened up with the plumpest cheeks anypony in the room had ever seen, with multiple chins below.
Sandy panted with disbelief as the growth finally stopped. There didn’t seem to be any words to describe her size now. She was purely massive, slightly bigger than her actual bed in overall mass.
Both Dell and Dane walked over to her side, admiring her body with pure astonishment. They both began to rub hooves over her belly, testing to see how far they could sink into her excessive squishy flesh. Every poke and prod caused a seemingly endless ocean of jiggle that took quite some time to calm down.
“Wow, Sandy. You...you’re certainly something. We’ve never even dreamed of a mare this big before. How...how does it feel?” Asked Dane
“W-Well...not bad I guess. But it kinda sucks not being able to move.”
“Don’t worry, we’ll stay here with you until you shrink back down to make sure nothing bad happens. If you want us to, that is” Dell offered.
“I..I think I’d like that. I should be back to normal as soon as we wake up.”
“Do you mind if we...uh...explore a bit?” Dane asked, still rubbing his hooves around the massive circumference of her belly.
“W-Well. I suppose this is a pretty rare thing. Alright, but no more getting too frisky. I don’t want to get even more ridiculously big than I already am.”
The two stallions spent quite some time afterward playing with all of Sandy’s new curves. Dell watched with amazement as he managed to get his entire hoof into her cavernous belly button. Meanwhile, Dane took turns slapping each of her flank cheeks, timing how long it took them to stop jiggling in response. Sandy could only sit back and enjoy herself. There was something strangely satisfying about laying there and letting the two play with her body. She wouldn’t like to stay like this for long, but it was fascinating to be so unrealistically big for just one night.
Eventually, the two settled down and the group got ready for sleep. They agreed that one of the brothers would keep watch while the other one slept. Sandy looked up with surprise as Dell climbed on top of her belly and stretched out.
“I’m actually big enough to be used as a bed, what a night…”
Author's Note
Just an idea I had for awhile and wanted to bring to life. I'll return to work on the next chapter of Equestria's Fastest Succubus soon.
