Sunnie Bun was not your average mare. She stood almost a head taller than most mares and stallions that walked around her as she strode her way through the crowd, looking for a new mark. She soon found what she was looking for: an elderly stallion, with a fancy gold watch and a small bag full of Bits, haggling with a shopkeep over a basket of apples. Sunnie’s smile grew wide as she made her way over. As she grew closer, her smile slipped and a look of alarm overtook her features. She stumbled over her own, long legs, almost bodychecking the stallion and sending his Bits flying all over.
“Oh! I’m so sorry!” Sunnie gasped, scrambling to her hooves and quickly picking up each and every Bit she could find. The stallion sniffed, glaring at her as she returned the bag, clinking full of coins. “That’s all I could find.” Sunnie said. The stallion’s glare intensified for a moment, and he quickly counted the Bits. He grunted, satisfied, and turned back to the shopkeep. Sunnie walked away, her head down, but her eyes danced triumphantly. Stuffed into the bag hanging on her side was the gold watch. She giggled to herself quietly as she looked around for another mark. She soon spotted another, a large mare, her butt hanging down over the sides of the stool, sat munching away on a hoofful of burgers. A diamond necklace glittered underneath her chins. It wasn’t going to be an easy hit, but Sunnie was sure she could pull it off without trouble. She started her approach, finding all too easily a small rock to trip her up. She slammed with perfect accuracy into the hefty mare, expecting to feel the mare tip over onto the table, or the stool crack, but she got… nothing.
Sunnie sat there for a moment, confused. Her forelegs were spread out wide, sinking deep into the flabby ass-flesh. Her nose was buried in the mare’s large crack, and she felt a flush running all over her face. The mare took a pause from her meal, turning her head to talk to Sunnie.
“You know dearie, if you wanted to touch, you could have asked.” The mare said cooly. Sunnie’s cheeks burned harder. She jerked herself back, and with a mumbled “sorry I tripped,” she ran off, the necklace forgotten. She realized with a start that she wasn’t just embarrassed as she melted through the crowd. She was jealous. Jealous of the mare’s size, her immovability. Despite being taller than average, Sunnie was stick thin. Where others grew out, she grew up. She knew with a sharp bitterness that stallions wouldn’t give her a second glance as she walked by, as there was nothing there on the first glance. Oh yes, she’d had suitors - she was smart and very pretty - but once they soon tired of cuddling with someone who was pokier than a porcupine. She resented the dumb fillies in her classes who had nothing to offer but a pillowy rear. If she’d had one, a large, bulging butt, she’d use it better than those bimbos, by Celestia! A massive, warm, heavy ass, one so big she’d barely be able to move. All she’d be able to do would be to sit and eat and grow bigger, and bigger, and bigger…
She stopped walking abruptly, realizing that her back legs were weak as she imagined being an immobile blob of fat. She shook her head, clearing away the fantasies she’d had ever since she was a filly.
‘I should get home. I’m too… tired. Yeah, I’m too tired. Not thinking straight.’ Sunnie turned herself around, walking back towards the pawn shop, and in turn her house. The owner, Sal, let her sleep next door for next to nothing. She helped out around the shop a lot, and he understood that the things she pawned in his shop weren’t just found laying in the street.
The door’s chime rang out sweetly as Sunnie walked in the door. Sal was sitting where he usually sat, at the counter, stubble framing his soft jaw. He puffed smoke from his pipe as she walked in, and blew a smoke ring at her.
“So.” He growled. “What fell from the sky today?” Sunnie laughed, and placed the watch on the counter. Sal floated it in front of his eyes, giving it a thorough once over. “Not a bad piece. Give ya 50 Bits, take it or leave it.”
“I’ll put half towards the rent.” Sunnie called out, already hunting through the dusty and musty wares of the pawn shop. One of her favorite pastimes was just to look through the magic section. Most of the items had lost their magic over the years, though some retained a lot more. Sunnie remember the day someone had brought in a stone dragon that had been enchanted to act like a real one. Sal thought it was junk. After it almost burned the store down, he quickly changed his mind. Something caught her attention today however. A large, dusty book, bound in what looked like snakeskin. Sunnie blew the dust off of it, but still couldn’t make out the title. “Hey Sal, what’s this book here?”
“It’s a potions book for ponies who have weight issues. Don’t know why he’d want it, but some green deer asked me to hold it for him until tomorrow. Didn’t have the Bits.” Sal chuckled. Sunnie carefully opened the door, flipping through the yellow and brittle pages. Most of them were for weight loss potions, things to curb appetites, the like. Bored, Sunnie flipped at random, until she came across a page that made her eyes bulge. Next to an amateur drawing of a mare with a rotund rear, stood a title: ‘Posterior Plumper: For those who want a little more junk in their trunk.’ Her breath quickened as her fantasy again intruded into her head. Her back legs rubbed against each other as she memorized the ingredients and the instructions.
‘Posterior Plumper: For those who want a little more junk in their trunk. Ingredients: 1 quart of milk. 2 quarts of chocolate. 3 Xanderroot, unsliced. 2 drops of Bloatbeetle venom. 1 tail hair from recipient. Pour contents into heated cauldron. Stir until glowing purple. Ingest until rear is preferred size. Growth may take up to two minutes to take full effect. Warning! Do not, under any circumstance, i-’
The ringing of the door chime made Sunnie snap her head up violently. She slammed the book closed, and scuttled down one of the aisles, her chest heaving, as Sal greeted a customer.. Her body tingled with excitement, and her thighs ground together even harder. For years she’d dreamed of being large and soft. Years and years, and now it was finally within her grasp. She felt giddy as she walked out the door, heading straight to pick up what she needed.
It was dark by the time Sunnie had gathered up all of the supplies she needed. However, in her excitement, she’d doubled the amount of ingredients as was required. The mare blew into the house, digging out a massive soup pot and immediately got to work. Into the pot went the milk, the chocolate, the Xanderroot and the Bloatbeetle venom. The mixture bubbled as she dropped the tail hairs in. She stirred and stirred, getting more and more excited as she did so. Finally, the potion was ready. She took a glass and filled it to the brim with the purple liquid. Her heart pounding, she gulped down the whole glass. She waiting expectantly for something to happen. Nothing did, for a moment, and then she felt a warmth permeate her body. She looked back over her shoulder, and saw with amazement that her ass was swelling, slowly but surely. She reached out and prodded it, and felt her hoof sink in ever so slightly. Dazed, Sunnie gulped another glass, and another. She moaned, feeling her ass balloon out behind her, growing larger and heavier with each passing second. She felt every new inch of ass flesh appear, and every pound it created. She drank more and more of the potion, moaning louder and louder, her mind cloudy with the feeling of her growth, unable to think beyond the sensation. Soon, she’d drank the entire potion. She belched, wobbling her ass around, knees so weak she could barely stand. Her pussy burned with desire, and she walked to her bedroom, her rump bouncing and jiggling for the first time in her life.
She collapsed onto the bed, one hoof reaching down around her slightly bloated belly, the other feeling her ass, caressing the softness. She’d barely started when she felt another rush of heat race through her. And then another. Sunnie looked back with a gasp. Her ass had doubled in size, and was still growing faster. She moaned, stroking herself faster, wanting to be bigger, feeling herself grow larger and larger. The bed creaked as she grew, the weight of her ass pressing her harder into the bed. She shrieked as she came, and in her orgasmic haze she didn’t even realize that her belly had begun to swell as well. She stood, unsteadily, not used to the new weight that covered her frame. Her thighs rubbed together as she waddled over to the top of the bed, tongue lolling out as she straddled the wooden headboard. She rocked back and forth, feeling her new pounds jiggle and bounce and drive her further, make her hotter than she’d ever been before. Her ass was unrivaled by anyone she’d ever met, both cheeks sagged under their own weight, but still they swelled bigger, and bigger. Her belly pooched outwards, swelling softly over the creaking headboard. Sunnie’s eyes were crossed as she came, and came, and came. The only thought that invaded her mind was bigger, bigger, bigger, bigger, bigger, BIGGER BIGGER!
Finally, the headboard decided it had had enough, and with a loud crack it shattered. Sunnie fell onto the bed, her new massive weight far, far exceeding the bed’s limit. It broke with an even more thunderous CRRRRACK. Sunnie’s vision went hazy as a scream of pure pleasure was wrenched from her throat. Her whole body rippled, causing an unending crescendo of osgasms, each more powerful than the last. Her ass was easily double, triple the size of the rest of her, when it finally stopped growing. Her belly made a soft cushion for her to lay on. In fact, her entire body had grown. Her thin body had plumped up slightly, although nowhere near as much as her ass. Sunnie whimpered as her pleasure wound down. Laying in the ruins of her bed, the now-massive mare fell asleep.
Sunnie awoke the next morning exhausted. She yawned and stretched, lazing around in her sheets before her belly rumbled enough to get her out of bed. She stood, and took a couple steps before stopping dead in her tracks. She wiggled her ass, feeling it jiggle and bounce. She turned and looked at the ruined bed. Her heart fluttered, and she raced to look at herself in the mirror. She skidded to a stop in the bathroom, and looked herself up and down.
The stick-thin pony was gone. What stared back at Sunnie was a voluptuous, curvy mare. Her face was fuller, and a new chin had been born from the new flesh. Her forelegs had plumped up considerably, and her chest had a mild wobble to it as she turned her head back and forth. Her belly hung low, down near her knees, jiggling slightly with each breath she took. Her ass, however… It looked like two soft beachballs had been glued onto her rear. They sagged down, but they were smooth. Just seeing her ass that big, knowing that it would remain that big from here on out made Sunnie bite her lip as her body flushed with heat. She wanted someone to play with her body… no, she wanted to make someone play with it. She wanted to feel someone squirm under her massive cheeks, she wanted to smother them in her fat, and wanted to…
Sunnie snapped back to reality as she felt pressure on her backside. As she watched in the mirror, her ass pressed against the wall, and pushed her forwards. She looked on, astonished, as she continued to grow… again. Pleasure soon overrode panic, however, and Sunnie again retreated to the bedroom, intending to finish her destroyed bed off for good...