Inside a dimly lit room, you, a human lay naked upon a massive, lavender love heart shaped bed. A huge dark shadow loomed over you, this shadow belonged to the massive pony known as Princess Luna standing right over you.
She was the size of a Shire Horse, if not even larger, with an absolutely massive backside. It was thick, meaty and wide, each cheek was an oversized balloon of soft, jiggly flesh, supported by a set of powerful, thick hind legs. She was a truly terrifying monster of butt. You were a tiny, insignificant little ape when compared to her mighty size.
"Are thou sure thee are willing to endure this horrible pain? Our spell We cast upon thee stops thou from dying, but does nothing to numb the pain." she asked in a most concerned tone.
"Yes, I love you Luna. I am willing to endure this pain so my body can withstand your mighty butt."
Luna nodded. "Okay, thou asked for it."
Without further ado, Luna gently sat herself down upon you, her mighty backside resting upon your lap, accompanied with a sickening bone breaking sound.
“Ahaaaahhhhhhhhhhhh!” you screamed with blinding pain.
The weight, the terrible… terrible weight. Indescribable pain soared through your body. Her monstrously heavy, squishy soft backside pinned you down from under its immense weight.
“Anon, We haven’t even started yet!” Luna shouted.
“I-I knnnooooooowwwwwwwww!” you screamed in anguish.
“Does thou wish Us to stop? We hate hurting thou.” she said in a soft voice, looking down at you with a look of pity.
“Nooooo….. I-I-I must do this! Ahaaaahhhhhhhhhhhh!” you screamed.
Luna sighed sadly, before her horn and your cock became wrapped in an azure glow. Through your endless screaming Luna magically forced you to get an erection, along with vastly increasing the thickness and the length of your member to the size of an actual horse cock, before gently magically positioning it before the hot and wet entrance of her marehood.
“Brace thyself Anon. It shall only get worse from here.” she said softly.
Your magically enhanced cock pushed into her hot, wet and tight depths, the powerful walls of her marehood tightly squeezing your long and thick shaft as you went into her. Not that you could focus on this pleasurable feeling with your pelvis currently broken.
When each and every inch of your large cock became embedded deep within her hot depths Luna lifted her massive backside off you by a few inches. However, the pain was still ripping through your body like a knife, thus you were still metaphorically screaming your head off.
Luna flashed her horn…. and… the pain was gone, along with your pelvis healed. Your heart was beating hard in your chest, you were breathing heavily, your sweat dripping off you like flowing water.
“Are thou ready?” she asked softly, staring down at you with sad, sympathetic eyes.
You gulped, nodding wordlessly.
With that Luna lifted herself several more inches up your cock, before slamming hard down upon you, a sickening bone breaking sound accompanying her impact upon your lap.
“Ahaaaahhhhhhhhhhhh!” you screamed in agony.
Luna lifted herself off you again, followed by magically healing your broken body, giving you a brief respite, before slamming her massive ass down upon you again.
“Ahaaaahhhhhhhhhhhh!” you screamed.
Once again, Luna lifted her rump up, then magically healed your broken body, giving you a brief moment, before she slammed her enormous butt upon you once again.
“Ahaaaahhhhhhhhhhhh!” you screamed.
Luna lifted herself up, then on schedule magically healed your body, before slamming her mighty rump upon you again.
“Ahaaaahhhhhhhhhhhh!” you screamed.
Luna lifted herself up again, healing your body once again. But this time, she began to wail in grief, tears falling down her cheeks over causing you so much pain and refusing to slam down on you this time.
“We love thee, our little human. Tell Us to stop at any time.” she cried out in anguish.
“I love you too, Luna. But keep going, don’t waste time healing me. Ride me faster!” you shouted.
With that Luna slammed harder than ever upon you, breaking your bones and making you scream in agony. Followed quickly by lifting herself up, without healing you this time, before slamming down on you again, before doing the same again and again. Repeatedly, without stop Luna rode you like the tiny, insignificant little insect you were. Through your screams, Luna cried out in anguish but held strong and never once relented slamming her massive backside up and down upon you, no matter how many times you screamed.
The sounds of flesh slapping against flesh filled the room, along with your screams and Luna’s cries of anguish.
“Anon, We hate doing this. But maybe if We do this it will quicken thy strength gain.” she shouted.
Luna slammed upon you, lighting up her horn with blinding light. A moment later, her huge rump began to ripple like jello, before beginning to rapidly expand out like a balloon.
The already massive mare grew higher and higher into the air, her rump expanding over the bed, quickly surpassing the size of even Princess Celestia’s rump. Her hooves elongated, spreading across the room. With great speed her body surged higher into the air, her already massive backside becoming fatter and fatter, bigger and bigger, heavier and heavier. Your cock grew larger inside her, to accommodate her growing marehood.
The bed beneath her gave a loud groan, before the wooden supports snapped like matchsticks from under Luna's increasing weight.
Soon, your world became nothing but darkness when Luna’s backside swelled beyond the point that you became smothered under the rapidly inflating mass that was her rump. The soft fat of her rump covered your entire body in thick layers of squishy soft fat, depressing deeply around your small form. With her weight now covering your entire body, this made the pain only even worse, your screams were muffled into the growing mass of her massive backside.
Her rump swelled more and more. Now, her massive, ballooning, squishy soft cheeks of her godly rump pushed against the very walls, the soft fat deeply depressing against them, threatening to destroy her very bedroom. It was only when her head touched the ceiling did the growth stop, but by that time she might as well be an African Elephant suffering from gigantism.
A single tear fell down her cheek from listening to the muffled screams you uttered into the vast mass of her gigantic backside.
Luna lifted her all powerful, colossal rump, allowing your screams to reach her ears in full. Not willing to listen to your pain, she quickly slammed her massive backside down upon you, muffling your screams beneath her mighty rump, followed shortly after by lifting herself up and then slamming down upon you again, doing the same again quickly after that.
The whole castle shook from the giant and mighty butt of Luna slamming upon you over and over again. Servants, and Princess Celestia herself were awoken by the great noise. This annoyed them somewhat, but they let Luna continue giving you the greatest workout session in the history of Equestria.
On and on, Luna slammed her gigantic rump hard upon you, her rump’s jiggly flesh moving wildly about as she did so. Through it all, Luna cried, hating the fact her rump was hurting you, but continued her work without stop.
Hours, upon hours went by. You continued to utter muffled screams into her giant butt. The hours soon turned to days, then weeks to months, and then months to years.
Until one day, Luna heard not a scream, but a moan from you.
“Could it be?” she said in a hopeful voice.
She slammed her massive backside upon you, only to hear you moan again.
“Huzzah!” she shouted excitedly.
With a flash, Luna was instantaneously restored to her Shire Horse sized body, to reveal your muscular, Super Saiyan like body, minus the hairstyle.
“The pain was worth it. Now, I can withstand the Moonbutt.” you said in a low, raspy voice.
The End
