Within the middle of a vast apple orchard there was a human, that human was you. You lay on your back, with a small, light weight, light blue, feathery winged pony bouncing on your lap. This pony had a rainbow mane and tail, and was the one and only Rainbow Dash. Also the sun was shining, as it usually does in this magical horse land.
Not to put humanity to shame, you were going to cum inside this sexy pony, because you weren’t a heretic. Your penis was inside her and you were going to cum inside her, because refusing to cum inside Rainbow Dash is heresy.
“Oh Rainbow Dash, I’m about to cum inside you, Rainbow Dash.” you said in a weak, raspy voice, overwhelmed by Rainbow Dash’s glorious cunt squeezing your cock inside her, demanding you cum inside Rainbow Dash.
“Oh Anon, yes! Cum inside me, Rainbow Dash!” Rainbow Dash shouted excitedly.
With that you uttered a loud grunt, closing your eyes as your legs became rigid, unleashing into her love tunnel, spurt after spurt of your seed shooting into her, cumming inside Rainbow Dash. Rainbow craned her neck back, uttering a loud neigh, riding you through your orgasm.
Rainbow made loud, happy whinnies, flapping her wings and repeatedly bouncing atop you as you came inside her. You grunted and groaned in pure bliss while humping up into her marehood like a madman, meeting her midway through her bouncing. You raised your arms to take a tight grip upon her backside, squeezing it to the point you dug into the thin layer of soft fat, quickly reaching the firm muscle beneath.
Nothing seemed amiss, other than your unnatural amounts of cum releasing into her again and again. But for some reason your hands soon began to sink deeper and deeper into her rump, along with the odd feeling of Rainbow’s bounces becoming a little harder each time her hips collided with yours.
Curiosity soon got the better of you, so you decided to open your eyes to see a most terrifying sight.
Rainbow was lost in her own little world, her eyes shut tight, moaning aloud as she slowly rose upward in height, her entire body becoming thicker and longer each time you released into her. Her growing form made a particularly strong emphasis to expand her rump, her blue bubble butt rapidly ballooning outward, augmenting in thickness and height by each passing second.
Her dripping wet, hot, tight marehood squeezed your cock within her, demanding more cum to be unleashed, your penis only too happy to oblige by filling her up with a continuous stream of cum, helping her grow bigger and bigger.
Your fingers began to dig deeper and deeper into her rump as her ass ever inflated in size like a balloon, her former muscular rump turning squishy soft to the touch, due to the enlarging mass of excess fat.
You sighed in bliss, basking in the wonderfully heavy, soft body colliding with yours. Rainbow’s rump kept slowly swelling bigger and bigger, fatter and fatter, heavier and heavier.
You pulled your hand back, before unleashing a hard slap upon her rear, causing her luscious rump to jiggle wildly about, along with her fat cheek smacking against the other one with a wonderful sound of flesh slapping against flesh.
Your cock suddenly released a much larger dose of cum into her, causing Rainbow’s cheeks to double in size, continuing from there to grow even larger by each passing second, quickly developing into ridiculous proportions of size, soon putting big booty pornstars to shame.
Pound after pound began to quickly add up, turning this from a pleasurable experience to a painful one. Things became quite uncomfortable when each of her humongous rump’s cheeks became more or less great big potato bags, filling with more and more potatoes, growing in both weight and mass.
“Rainbow stop! You’re hurting me!” you cried out in pain.
Unfortunately, your cries came upon deaf ears, the mare was oblivious to your plight as she moaned like a bitch in heat, continuing to grow larger and larger. Your seemingly endless amounts of cum wasn't helping things out either. You held onto the hope your cock would become too small for her and thus slip free from her expanding marehood. But alas, you felt your cock grow inside her, thus not allowing you to escape your expanding big fat pony butt prison.
‘Why can’t I cum inside Rainbow Dash without something crazy happening?!” screamed your thoughts.
Her gargantuan rump quickly surpassed even the great big butt of Celestia. Such was the expansion of her ass that your hands literally began to slip away, becoming no longer possible to even hold the cutie marks upon her growing rump.
You repeatedly tried to get her attention by shouting her name but she could not hear you, eventually she had grown so large and heavy you could not form coherent words other than screams of anguish, due to the agonising pain you are going through from the ever growing mass atop you.
To make things even worse, your cock, as if it knew that you were thinking about escaping began to pulse powerfully with renewed vigour, filling her up with massive spurts with gooey human spunk like an automatic, military grade combat shotgun.
Rainbow moaned aloud, her body growing even faster with the now more frequent and larger deliveries of your seed into her, feeding her growth. Her rump and body in general went through a series of violent growth spurts, soaring upward into the air, quickly beginning to grow over the surrounding trees.
A great canyon formed between you, entrapping you between two great and mighty big blue cheeks, only becoming more and more greater. Your world became lost in darkness, since her rump had swelled so large in size to the point your entire body was smothered in soft flabby flesh covered in soft blue fur. Said flesh depressing deeply as it folded around your body like soft dough, all the while her ever growing butt repeatedly bounced atop you, only growing larger and larger as your cock continued to feed her growth. Somehow, you were still able to breathe from under her.
Her body grew without stop, her massive, growing rump digging you into the earth beneath her. Higher and higher she rose into the air. Her tremendous, enlarging weight just becoming more and more heavy, her massive backside slamming hard upon you over and over again, shaking the very land around her, causing small earthquakes, with enough force to cause apples to fall off the nearby trees.
Her colossal rump had now become so large it began to push against nearby trees, which struggled to hold back the ever growing tide of expanding flesh. The soft fat of her massive rump folded around the trees, their soft fat was deeply depressed, whilst her cheeks pushed against them.
Gone was the little petite mare you fell in love with, replaced by a behemoth, fat hippopotamus suffering from an awful case of gigantism, and she was still not done growing in size. Somehow, the integrity of your body still held together, despite the ever growing mass of her body hitting into you by bouncing her rump. Thankfully, the pain went away, replaced by a growing heavy softness pressing down on each and every inch of your form. Must take sometime for their magic pony pussies to release more stronger protective magic on their lovers.
Rainbow made a loud neigh, slamming hard down upon you, proceeding from there by grinding her rump against you. You groaned in delight, loving the feel of her squishy soft fat rolling across your bare skin like warm, flowing water.
Your cock in answer unleashed a massive load of cum into her, causing her to go through a massive growth spurt.
Rainbow skyrocketed into the air, her massive, inflating cheeks knocking trees over and then bulldozing over them to crush them into sawdust.
Rainbow’s butt became a massive, inflating bouncy castle rump, her flesh rippling like jello in the wind as more and more mass added to her ass. Her body surged up over the trees, her heavy rump digging into the earth as her weight ever increased, forming a deep crater from the monstrously large pegasus.
Eventually, Rainbow stopped growing when your cock finally finished releasing into her, but by that time she was about as large as an Argentinosaurus Huinculensis, who too had a horrible case of gigantism, particularly in the rump area, where the growth seemed to be at its strongest. Rainbow’s rump had became so large it was quite disproportionate to the rest of her body. Nonetheless, the gigantic cheeks of her ass were two perfectly round, but still enormous hilly monstrosities. Her rump now was a super weapon, the only reason you aren’t a bloody jelly is because pony pussies were magical.
Rainbow Dash herself has become a monster horse, a big, fat, well fat in the rump at least, most of the fat seemed to have gone to there.
You felt your cock rapidly shrink and return to its natural size. Now, nowhere near compatible for her unbelievably large backside, thus it simply slipped free out of her massive, plump marehood.
“Anon, where are you? Why am I so big?” came Rainbow’s voice in a worried tone.
You mumbled through the vast mass of flesh covering, and pressing down on each and every inch of your tiny form.
Rainbow quickly jumped to her hooves, her powerful, heavy hooves hitting into the ground with such force it caused dozens of trees to fall over and her hooves to dig deep into the earth. Once she stood up, the massive mare turned around to stare at you with wide, panic filled eyes.
“Are you okay Anon?!” she shouted, her voice echoing across the land by its sheer volume.
“Yep, I’m okay Rainbow.” you replied weakly.
Rainbow leaned her massive head down, before opening her mouth wide to unleash her massive tongue. With utmost gentleness the massive mare used her tongue to lick your entire body, drenching your whole form with her warm saliva.
“Curse ya Anon and Rainbow Dash! Some of these trees were mah friends. Who Ah knew from pip to apple!” roared Applejack.
“Don’t worry Applejack, I didn’t destroy them all.” said Rainbow Dash, before speaking in a smug tone. “Look on the bright side, I’m a big pony now. I can save Equestria by just sitting on whoever is the next big bad villain is.”
“Well, if ya put it that way it does sound rather swell. Just be careful to not knock over any more of mah apple trees.”
“Hey Anon, you wanna come inside me and cum inside me while inside me?” she said sexfully.
“Oh Rainbow, I think you're big enough.”
“Heresy! I can never be big enough puny human!” she growled angrily, looking down at you with a death glare.
You gulped in fear. “Okay Rainbow Dash, I’ll come inside you and cum inside you while inside you.”
“Awww yeah! I’m going to have some big ass rainbows!” she shouted excitedly, her powerful voice echoing across the land.
The End
