Her Growing Sparkles

by Bendy

Rating: mature
Tags: Twilight Sparkle, Anthro, Anon, My Little Pony: Friendship is Magic, Second Person, Fetish, Comedy, Romance, Porn, Sex, Human
Length: 4935

Your horsewoman girlfriend Twilight Sparkle tests out a new spell. She gets really big.

Your horsewoman girlfriend Twilight Sparkle tests out a new spell. She gets really big.

Co-Writer: primortal

Published 2021-10-25 09:10:02 UTC
Last updated 2021-10-25 09:10:02 UTC

Big Twilight

You, the human, held the soft, furry hand of your human-like, equine purple alien girlfriend. Unlike a horse, she stood on two legs and had human feet and hands. Her face was cuter than the horses you knew back home on Earth. Her snout was far less pronounced than that of a horse, it was much shorter, and cuter looking. She had a pretty-looking face, even if her purple eyes were huge. She had a pair of feathery wings upon her back and a horn atop her head.

She possessed a tail protruding out from her pants from behind her. Despite the somewhat uncanny nature of her human body crossed with an equine appearance you could not help but find her sexy. Plus her big floppy ears were really cute.

Her name was Princess Twilight Sparkle. Apparently, she had a surprise for you. You stood at least one foot over the five feet tall horsewoman. She was dressed in a white tank top, black pants, and a pair of white sneakers. You were dressed in a fine, black tuxedo.

Twilight’s species was more affectionately known as a pony. Her particular subspecies of a pony was known as an alicorn.

The alicorn mare guided you up the stairs of the Golden Oaks Library. Once upstairs, she brought you into her bedroom. You wasted no time and stripped yourself naked for her. Your monstrously large cock stood to attention, standing about 20 inches long, and 8 inches thick. It came with a set of grapefruit-sized balls. You have no idea how or why it had grown so big, you just simply chalked it up to the seemingly magical nature of this world you found yourself in.

Your two-legged pony love had no issue sharing you with her five best friends. You had six loving mares to suck and fuck your dick at any time. Despite the fact, these horsewomen were small, they were able to take you inside them. Their pussies and mouths seemed to be able to stretch into different dimensions as they took your massive cock inside them.

You were disappointed that pretty much every one of these cute pony women you saw had very small tits. They were no bigger than a teacup. And, for the most part, the horsewomen here were quite petite.

Except for their backsides. They were quite plump. Still, you wished the ponies didn’t get the Lola Bunny treatment like everyone else in this magical world. It seemed, even here, you were not able to escape the Unsexy Inquisition back home on Earth. Butt, then again, Lola Bunny had a thick ass. You are so confused.

Anyway, Twilight pushed you onto the bed and made to straddle herself over your lap. Your monstrously large cock came to hot dog the cheeks of her ass through her pants, and it came to rest upon her back. You brought your hands down to take a tight grip upon her buttcheeks.

Twilight stared down at you with a smirk on her face. “Like my ass, huh? You’re going to get a lot more where that came from, big guy,” she said in a hot breathy voice.

“Oh?” you inquired, raising your right eyebrow curiously.

“Yeah, I’ve been working on a spell these past few days. Don’t worry, it comes with weight protection as well, and I’m able to contain myself in my room within a pocket dimension,” said Twilight, lighting up her horn with magic.

“Are you sure this is safe?” you inquired, being one of the first times she had even mentioned ‘pocket dimensions’ since you met her. “I don’t want you to hurt yourself or anything.” Twilight giggled and gave you a small peck on the neck. Her lips felt soft and slightly fuzzy upon contact with your skin.

“Don’t worry sweetie! I’ve been really preparing myself for this,” she said with a wink, and with that, she flashed her horn, but nothing happened. But then you started to feel a tremendous weight placed upon you, causing you to hiss in pain. The weight was borderline unbearably painful, but nothing too much. “I’m now as heavy as an elephant on top of you. I've vastly increased the density of my body,” she said as you heard a creaking sound before the bed collapsed underneath her.

“THIS?!” you gasped, trying to move the ‘massive’ weight off your lap before it crushed your pelvis. “THIS IS THE SURPRISE!?!?” To which Twilight blushed, looking quite forlorn at your reaction.

“I was merely trying to demonstrate the weight protections.” she said meekly, “Think about it, your bones should be shattered into dust, and your legs should be nothing but a bloody paste under me. But you are fine.”

She flashed her horn again, but this time you really didn’t feel anything different. “I just doubled my weight. But do you feel any different? I now weigh about eight tons on top of you.”

You sighed in relief. “Yeah, I’m sorry I ever doubted you.”

She giggled, bringing her right hand to her mouth. “That said, I may need to magically reinforce the floor. Otherwise, my ass will come plowing through it if I’m not careful. Now, are you ready for me to increase the size of my ass and boobs over you?”

“Yeah, I would very much like that,” you said, giving her asscheeks a tender rub with both of your hands. You wish you could feel them through her pants.

Her horn lit up with magic, you saw her teacup tits swelling inside her tank top. Your hands resting upon her cheeks were pushed back at her ass swelled as well. And if you didn’t know any better, you swore Twilight seemed to have gotten taller by at least several inches.

Twilight smiled sheepishly. “Well, that didn’t happen last time. I seem to be getting taller as well.”

You could see her clothes beginning to rip and tear, revealing small spots of her purple fur underneath. Your hands upon her butt made contact with some of the softness of her ass under her clothes.

Twilight rose up to meet you at eye level. She discharged her horn, stopping her growth. Her white tank top barely contained her massive, purple breasts underneath. Each one was about the size of a watermelon. You smiled as your eyes met. “Hey there, beautiful,” you said before you gave her a kiss on the lips. Her lips felt wonderful, they were soft and slightly fuzzy. Unlike you, she was covered in purple fur.

Blushing deeply, your lover placed a hand on your chest. “Hold on there sweetie,” she said as she readjusted herself.

“Allow me to do a brief test,” she said as she flashed her horn, and for a brief moment, she was back to normal size, before jumping back to her new size. “Good. At least I can reverse my size if need be. Incidentally, I feel that my magical energy pool has increased with my new size. Compared to how I am now, I was far weaker when I was smaller.”

“Interesting,” you replied, grinning as you resumed kissing her along her neck and muzzle. Had you not been so focused on making out with your newer, bigger, bustier girlfriend...you’d have noticed that she wasn’t done growing. Even she didn’t seem to realize it at first, so caught up in these new sensations, these new experiences, (not hurt by the fact that her body felt much more sensitive) as you kissed along her chin and lips.

Loud ripping sounds could be heard as her clothes struggled to contain her growing body. You stared in awe as her swelling breasts tore through her tank top. Her massive tits were now free from the tight confines of her tank top. This was followed shortly by her ass exploding out from her pants, and her heavy butt coming to land upon your lap with a meaty slapping sound. Much of her clothes were in pieces all over you, and the bed below. The bits of clothes that remained were wrapped around her relatively thin torso. But even then, her clothes were barely hanging on.

Twilight pulled away, and looked down at you with a smug grin, and flashed her horn, teleporting away the last of her torn clothes. “Going to try to hold back my growth. I’ve cast a growth suppression spell. I want you to drink my milk first before my growth gets totally out of control.”

The soft feel of her furry body against your bare skin was marvelous. She was soft and warm. You wondered why she even needed to wear clothes if she had fur. You drooled at the sight of her monstrously large breasts presented before you. Her tits were nearly two times larger than your average watermelon now. They defied the very laws of physics and didn’t sag in the least even with their enormous size. Her ass down below covered the entirety of your lap, and much of your upper legs. Twilight must be standing at least 7 feet tall, at least a foot over you. Your huge cock lay sandwiched between the thick cheeks of her ass.

You raised your hands up and placed them upon her cutie marks. Your hands sank deeply into the plush soft cheeks of her ass like soft memory foam. You roamed your hands across the wide expanse of her ass, feeling up her wonderful plush softness.

With a smirk, you pulled your right hand back and delivered a hard slap upon her rear. This created a wonderful sound of flesh slapping against flesh as her cheek smacked against the other one.

Twilight panted for breath, and sweat poured down her forehead. Her horn was glowing brightly to try to hold back her growth. But it was no use, the mare subsequently jumped up in height by about two inches. This was enough to cause her to crane her neck back and utter a loud horsey whinny of pure bliss. Her marehood unleashed a torrent of her creamy marecum upon your lap. The feathery wings upon her back flapped excitedly during her release.

Twilight sighed in bliss when she came down from her high. “Your… your slap caused me to have a small growth spurt. I… I…. nearly l-lost…. control back there and unleashed my true growth. It’s like trying to use a small dam to hold back an ocean pushing against it,” she panted before her expression turned stern. “Now would you please drink some of my milk?!” she asked, aching to feel you drink from her.

“As you wish, your highness,” you joked while licking your lips. You playfully licked along her right nipple’s surface, sending shivers and shakes through your lover’s body. A mini growth spurt came over her, but this time only in her tits, as they swelled by several more inches towards your face. “How convenient!” you quipped.

Twilight giggled. “Sorry, I could not help myself,” you only chuckled, winking before you suddenly sprang into action!

Twilight gasped when you leaned your head forward and took her plump, pink nipple into your mouth. Her thick and creamy milk came spewing into your mouth, it tasted buttery, and with a hint of sweet fruitiness to it.

You felt the need to suck her left titty, didn’t want it to feel neglected. Twilight sighed sadly when you pulled your mouth away from her right nipple, “What’re you doing?” she whinnied, looking at you with sad puppy-dog/pony eyes.

You immediately put her fears to rest when you took her other nipple into your mouth and suckled upon it hard. She moaned softly, her tits swelled even larger again by several more inches. More milk than ever came spewing into your mouth, and the nipple was soon almost too big for your mouth to comfortably hold it.

Twilight moaned heartily, as she began to jerk her hips back and forth, grinding her massive backside over your cock sandwiched between her thick asscheeks. You uttered a muffled cry of pure bliss around her nipple.

Twilight’s tits swelled even larger again, and the volume of milk drastically increased. You found yourself choking. You pulled back and coughed, excess milk coming to fall out of your mouth during the process.

You decided to slap her ass some more to playfully punish her, but this time with both of your hands at the same time. This triggered yet another growth spurt, but this was far stronger than before. Twilight cried out a loud neigh and unleashed a deluge of liquid upon your legs as she orgasmed from the double buttslap. Huge volumes of thick and creamy milk came squirting out of her tits as she jumped upward in height by at least 3 feet. The mare was now about 10 feet tall over you. The cheeks of her ass were now so massive you could not fully wrap your arms around it. You could not even reach her cutie marks anymore. Her breasts above were beach-ball like in appearance above you.

Twilight looked down at you with a sheepish smile on her face, her cheeks lighting up with a pink blush in embarrassment. “Have I gotten too big?”

“No!” you answered firmly, giving her ass another slap with your right hand, triggering her to grow slightly larger by about two inches. “You can always make yourself smaller if need be, right?”

“Of course,” she said, nodding. But a small part of her didn’t want to, a part that enjoyed being so big, bigger than you.

Twilight lifted herself up and positioned her marehood over your cock. In one fell swoop, she dropped down and took the entirety of your member inside her. You hissed in pain from the heavy impact of her massive backside hitting your lap.

You raised your hands up and took hold of her plump asscheeks. Your hands sank deeply, like memory foam into the plush softness of her ass. She giggled at the feel of your cock inside her. “Anon, you feel far smaller now. I don’t think your cock can fill me now.”

“But still good, right?” you asked in a worried tone.

“Yes, it's still good. A pony’s marehood can clamp down really hard.”

She demonstrated her point by squeezing her pussy hard around your cock inside her, causing you to moan in pure bliss. As foolish as it was, you attempted to lift her by pushing your hands upward against her massive ass. Twilight giggled, flashing her horn, followed by jumping up in height by another two feet, making her stand at a mighty 12 feet over your puny form.

“Nice try short-stuff, BUTT this ass isn’t going anywhere.” she teased. “The more you resist the bigger and heavier it will become.”

“Butt I want it bigger and heavier!” you shouted, slapping her right buttcheek with your hand, triggering her to grow once more by at least 2 inches. Twilight giggled in reaction as her body swelled larger over you.

“If that be the case, give it to me my love. Slap my ass all you want,” she said in a hot breathy voice. “I’ll just keep getting bigger and bigger the more you slap my butt.”

With that, you repeatedly slapped her ass, non-stop, triggering her to have continuous growth spurts. Twilight moaned aloud, her buttcheeks air ballooning over you, her little lover. “Ooooooh! Yes! Make me bigger and stronger!” she cried out.

Twilight began to bounce her massive, growing ass over your puny form. She made a series of loud moans and horsey whinnies as she did so. You hissed in pain from the heavy impact of her massive backside hitting your lap. Each time she landed, she hit you with greater and greater force as she became ever bigger and heavier. Despite the pain, you continued to slap the holy hell out of her ass to fuel her growth even more, you wanted your sexy girlfriend to be bigger and stronger.

Your giantess girlfriend howled like a banshee in pure bliss. Her massive ass covering your body blocked out much of the noise. “Oooooohh! Aaaaaahhhhhhh! Mmmmmm! Yes! Bigger! Bigger! Make me bigger! I love this! Keep slapping my ass so it can grow even bigger! It’s so big and sexy thanks to you!”

“Oh! Yes! Twilight I love your massive ass! I want your ass bigger too!” you shouted.

With great eagerness, you continued to slap the holy hell out of her ass. She just kept getting sexier and sexier the bigger she got. Twilight, in turn, rewarded you by repeatedly slamming her growing backside up and down upon you with greater and greater force. You hissed in pain from the heavy impacts of her immensely heavy ass smacking against your puny form.

Her thick and meaty ass jiggled wildly like jello during her bounces. Wonderful meaty slapping sounds of flesh, slapping against flesh were created as her buttcheeks smacked against one another continuously. At the same time, her ballooning boobs jiggled wildly about, and smacked against each other, creating wonderful meaty slappings sounds.

Bigger and bigger, fatter and fatter, heavier and heavier her gigantic ass grew upon you. You couldn’t get enough, you could see Twilight’s massive ass air ballooning out from behind her by magical aid even as you lay smothered under the darkness of her gargantuan butt. She just kept getting sexier and sexier the bigger she got.

She cried out a loud whinny as her milk came spraying out of her tits, staining the walls of her bedroom. Down below, you were showered with a monsoon of creamy marecum blasting over your body. You began to fill her less, and less until your cock came slipping out of her expanding marehood. Twilight made to squeeze her massive asscheeks together in order to smother your cock between their wonderful heavy softness, creating a makeshift vagina for you. You sighed in pure bliss at the feeling of your cock being smothered by her buttcheeks.

The ceiling and the room around Twilight began to expand in all directions to accommodate her rapidly growing body. She could grow without limit it seemed. And you were more than happy to continue to help her grow, grow, grow, and grow. You were still able to slap her ass even if her ass had grown absolutely enormous to the point she was at least a full-blown elephant over you. It seemed your hand was able to slip into some sort of portal dimension to allow you to slap her. Without her magical aid, you would not be able to touch her ass.

You couldn't get enough of Twilight’s massive ass, you wanted her ass to keep getting bigger and bigger without stopping. “Oh Anon… I love you. Keep slapping my ass. Help me get bigger and bigger,” she moaned.

Without a word, you continued your slapping of her ass. With that, Twilight began to grind her ass over your smaller form, her enormous buttcheeks came rolling over you like a gentle steam roller. Her hair swung back and forth, and her tail wagged excitedly from side to side as she grinded herself over you. Her cheeks rolled over you like a gentle wave at the seaside washing over you. The feel of her buttcheeks was like the softest, and warmest blanket you have ever known. It seemed to get ever softer the bigger it got.

Twilight reached her hands back and placed them upon her air ballooning buttcheeks at her cutie marks. Her hands sank deep into the squishy softness of her enormous backside like soft pizza dough. She stopped grinding her hips and remained in place over you, her lover. However, even while not moving her ass jiggled wildly about like a stormy ocean as new layers of fat were pumping into her ass with each subsequent slap you delivered to her buttcheek.

You finally stopped slapping her ass when her massive butt reached 30 feet in height. Her huge ass alone was taller than a two-story house. Her heavy buttcheeks lovingly squeezed your cock between them as they lay smothered in their wonderful, warm, bubbly softness. Her tits alone were the size of a small blimp each.

You raised your hands up, and with Twilight’s magical help you were allowed to embrace her ass. Your hands’ phased through portal dimensions, allowing you to lovingly fondle her ass to your heart’s content. Your hands sank deeply into the plush softness of her ass.

For quite some time you merely felt up her wonderful ass, admiring your handiwork from all the slaps you gave it to make it bigger. And with Twilight’s (admittedly huge) hands resting on her own backside, you were able to make contact with hers. Twilight reacted quickly when she felt your right-hand touch off her own upon her butt. With loving tenderness, she dimensionally phased your hand into the palm of her hand, and then she gently locked her fingers together, wrapping your hand in a warm and soft embrace as she held your hand.

“I love you, Twilight,” you said softly, kissing her right buttcheek.

“I love you too, Anon,” she said softly. You felt a strange wet sensation against your right cheek upon your face, which came accompanied by a smooching sound. It seemed as if she magically kissed you.

The two of you didn’t move for quite some time. You simply ‘held hands’, or the equivalent of holding hands with her as a giantess. No growth, or grinding, quite simply love. Until at some point you could no longer stop yourself. You could not help yourself, you wanted Twilight to be even bigger. And so you delivered another slap to her left buttcheek with your free hand.

Twilight giggled happily as she grew several more inches into the air over you, new layers of fat pumping into her ass caused her fat buttcheeks to smack against one another with a loud meaty slapping sound of flesh, slapping against flesh.

Twilight flashed her horn, growing your cock upward between her thick asscheeks. You sighed in pure bliss as your growing cock came to be ensnared deeper into the bubbly softness of her cheeks. Your legs kicked weakly underneath you, and you uttered a muffled moan into Twilight’s bubbly cheek as your cock’s tip came to kiss her marehood. Twilight's vagina welcomed your cock back inside her with a tight squeeze. Inch by inch, you grew inside her, until your cock came to kiss her deepest barrier.

Your cock didn’t change in thickness, it didn’t need to with the sheer strength of her vaginal muscles squeezing your cock. You soon could not help but slap her ass again with your right hand, thus Twilight subsequently grew once more into the air. Her pussy became just a bit deeper, and your cock was no longer able to kiss her deepest barrier. Fortunately, once Twilight was done growing several more inches into the air, your cock grew inside her pussy to match her new size, and it soon came to kiss her deepest point again.

Twilight giggled, before she lifted herself up high into the air, before slamming her massive ass down upon you with a loud boom. You hissed in pain from the heavy impact of her massive ass. Before you could recover, she did the same again, and again… and again. You wanted to slap her ass to make it even larger and heavier, but you were paralyzed from the sheer force of her massive rump hitting your body. Your body spasmed uncontrollably underneath her.

Twilight’s buttcheeks repeatedly slammed down upon you like two super heavy anvils. It seemed Twilight knew you wanted to slap her ass, since you saw her horn lighting up with magic. The mare subsequently began to slowly inch upward, her ass slamming down upon you with greater and greater force.

“I’ll grow bigger for you, my love,” she said softly.

Her powerful marehood clamped down hard on your cock. You were close. You could feel it, the pressure and pleasure building up to a crescendo as she slammed her body down upon your lap one final time. You heard a bizarre noise, like somewhere between a fog horn and the finale of an opera tenor’s vocal performance… only to realize it was you… as you came hard inside the massive purple pony. She too climaxed in response, drenching you completely in her marecum.

The two of you sat there, panting and sweating in the afterglow. “That… that… was amazing.” you gasped while rubbing your pony lover’s immense marehood. Or at least as much of it as you could reach at her current size. (Without her magical help, there would be no way you could reach her marehood with your hands. Portals are helpful) Twilight shivered and giggled as she leaned back, trying to get a good view of you.

“YOU were amazing Anon,” she said seductively, blowing you a kiss as she made her way to stand up. The sensations of her pussy letting go of your sensitive cock almost made you a quivering mess. Much to your chagrin, it seemed to have shrunk back down some.

Your cock went back down to its ‘normal 20’ inches’, if that could even be considered normal for a human. Again, you loved magic.

Suddenly, your train of thought and bizarre introspection was interrupted with Twilight moaning as she fell upon one knee, holding her stomach area. It was hard to tell if it was the kind of moaning that came with ‘pain’ or if she was getting aroused by it.

“Hey… Twi… you okay?” you asked, trying to stand up despite the state of your legs.

“Something is… going on… inside me,” she mewled, her lips quivering as a soft purple light began to illuminate her crotch/stomach area. “Like a dam… about to… burst.” she panted, her pussy now dripping from the sensations.

You flopped onto the ground, your sore and aching leg muscles refusing to work. Twilight’s massive ass did a real number on you. It felt like you had just done a great heavy weight lifting session at the gym. You wanted to help her, but kinda knew it was pointless. You were as magical as a plank of wood. “Can’t control it… can’t… can’t...” groaned Twilight Sparkle as she suddenly stopped mid-sentence. “Oh no.” she whimpered, a sort of sloppy grin formed on her face as her eyes widened.

“Hey, sweetie…,” you started, looking up in concern, “you o-” before it happened.

‘Dam Bursting’ was an apt metaphor, but not just of Twilight achieving an epic climax, her body seemed to follow suit. For a brief second the room was filled to the brim with purple horse ass and tits… at least that’s all your mind could remember, or register, as the alicorn exploded in orgasmic growth. You got slammed, again, by her butt… yet the word, the phrase seemed to be severely lacking in describing what was happening.

Yeah, you were not just ‘pinned’ by Twilight, but almost enveloped by her body. She filled all your senses, almost as if she became your world for that brief moment. All you could see, hear, and even taste, was the not-so-little pony.

You hissed in pain, Twilight was bigger and heavier than ever before. You were thankful her weight protection was strong. Otherwise, you would be nothing but dust now. Yet she was clearly ‘stress-testing’ the limitations of these protections. “Are you okay, sweetheart?” she asked, her voice ripe with concern.

You liked the pain, you loved the feel of being dominated by your super powerful girlfriend. Even now, you wanted even more from her. Weakly, you raised your right hand up, and answered her question by lightly slapping her butt, causing her to grow by several inches into the air, and become even heavier and bigger over you.

Twilight smiled sheepishly, the pocket dimensions of her room barely managed to contain her massive body. Her buttcheeks pushed against the walls, the soft fat conceding deeply from the applied pressure. She sighed in relief, when the walls began to expand away from her body.

“Hehe. Anon, we nearly broke the pocket dimension. My ass may have nearly rolled over Equestria, and perhaps far beyond that. By my calculations, my buttcheeks should be touching off the edge of the solar system. I have practically gone supernova.”

“Would anyone have died?” you asked.

“No… my magical strength would have stopped them from dying. I am basically a God now at this size.”

“If that be the case, you want to be even bigger, my love?” you asked.

There came a flash, and your love Twilight was vastly reduced in size. She was a mere 7 feet tall as she lay on top of you. A foot over you. Nonetheless, she had a pair of huge watermelon-like tits before your face.

“Let’s hug and kiss first,” she said softly.

You hugged your girlfriend, and kissed her. She in turn kissed you back. Her long equine tongue came into your mouth. Human and pony tongue swirled about in tender intimacy. You held the kiss for quite some time, before Twilight pulled away, and flashed her horn. You were then subsequently hit by an avalanche of giant pony ass. You hissed in pain from the heavy impact of her massive ass, but you would have it no other way.

And thus you slapped her astronomical ass once again, triggering her to grow several more inches into the air to become even bigger and heavier.