“A horse obsessed with strength and a dog dominated by his appetite unleash a strange pact: one becomes a mountain of muscle, the other a living hill of fat, until they leave behind forever the "Little" in Little Pet Shop.”

An AT with https://www.furaffinity.net/user/leroytheyeenposs/

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The day started normally at the Little Pet Shop until Harvey, the store clerk, arrived carrying a large box with a shipping label on it. As soon as he set it on the counter, all the little animals rushed over to take a peek, their shiny eyes asking, “What’s in there?” The human smiled and began handing things out: a sparkling accessory for Chloe, a new guitar for Viv, a toy for Squeaks, and even a pair of tiny dumbbells that Chet proudly lifted.
When it was Stu’s turn, the little blue dog could barely contain his excitement. The owner pulled out a huge jar of chocolate treats, and Stu darted forward like lightning. But just before his paws reached the prize, the jar floated up, out of reach. Plop! Stu ended up rolling on the floor with a frustrated look, while the human looked at him seriously and said that, for his health, he’d have to go on a diet for a few days. The jar went straight to the top of the refrigerator, at a height impossible for the dog.
The rest of the animals nodded sadly, admitting that maybe he really did need to lose a little belly. Stu put on his saddest face, teary-eyed, tail drooping, but that didn’t convince Harvey. Chet gave Stu’s belly a playful tap with his hoof, which sounded soft and bounced a little, making the others giggle a little. One by one, they went off to enjoy their gifts, while Stu stayed behind, staring at that jar.
Stu wasn’t about to sit quietly while everyone else showed off their new presents. That night, when the lights went out and Harvey went to bed, the blue pup opened one eye, then the other. Carefully, he sneaked past his friends, making sure not to wake anyone. But—bam!—a direct stumble onto Chet’s dumbbells! The metal clinked on the floor, and Stu held his breath. No one moved. He sighed in relief and kept going.
The refrigerator waited for him at the back of the shop, towering like a mountain. Stu hesitated for a second, but then his stomach growled, pushing him forward. With a spoon between his paws, he forced the door open just enough to climb inside, using the shelves like steps. Every level held delights: cupcakes, ice cream, and candies—and Stu couldn’t resist taking a little bite from each, getting rounder and rounder as he climbed.
Finally, clinging to the door, he gave a desperate leap and grabbed the top edge. He kicked, slipped, and struggled—until at last he pulled himself up. And there it was: the enormous jar of treats, shining with its chocolate treasure. Without wasting a second, he popped it open and began devouring. One, two, ten, twenty—until there were none left. Stu fell onto his back, panting happily, his belly round and tight like a drum.
The way down was an odyssey with his new “luggage” of sweets; every step was clumsy and heavy. Still, with effort, he made it to the ground and carefully closed the fridge, as if nothing had happened. Then, dragging his swollen belly, he waddled back to bed, satisfied and a little bit wider.
Sunlight streamed into the shop, and, one by one, the little animals started to stretch and yawn. Stu got up too, though with dark circles under his eyes and a sluggish step, still weighed down by his midnight adventure. But the moment Harvey served breakfast, his gluttonous instinct awoke again, and Stu dove into his bowl, eating as if he hadn’t touched food in days, ending with his belly even rounder.
Meanwhile, Chet was already on his workout routine with his new dumbbells strapped to his front legs. He moved in exaggerated motions, puffing out his chest and showing off muscles that, honestly, looked the same as yesterday. The cowboy horse strutted around, bragging about his strength and daring anyone to doubt him.
The little monkey was the first to poke fun “If you’re so strong, why don’t you lift us?”
Chet accepted without hesitation. He lined them up on his back and lifted proudly. “Easy!” he said with a confident grin. Then he raised the stakes: he hauled the little train they used to ride in. He even tried with Delilah, the monitor lizard, who wriggled angrily until she broke free and chased him halfway across the shop.
The challenges kept escalating until someone proposed the ultimate test: Harvey’s tube TV, huge and heavy like a block of iron. Chet planted himself in front of it, spat on his hooves, and braced under the cabinet. His muscles tensed, veins bulged, and his determined face turned completely red. The TV barely lifted a few centimeters before crashing back down with a thud.
Silence lasted a second, until Squeaks quipped, “Guess you’re not that strong after all.”
Between giggles, the others drifted away, leaving Chet alone on the floor, gasping for breath, sweat beading on his forehead. That’s when, turning his head, he noticed a forgotten box nearby. Inside were several VHS tapes. Curious, he read the titles: Bodybuilding for Beginners, Workout Routines, and How to Forge a Body of Steel.
Chet’s eyes lit up, and still stung by the TV incident, he plugged in the VCR and popped in the first tape. On screen, a group of humans in tight spandex appeared, bouncing and stretching to 80s music. Chet raised an eyebrow, half-confused, but tried imitating their movements with his dumbbells anyway.
It was in the next VHS that he found him—a true muscle colossus, a man so broad he looked carved from stone. Every inch of his body was covered with massive, defined muscles, and his booming voice filled the screen “This is the routine to sculpt a body of steel like mine!” As if that wasn’t enough, for the grand finale, he grabbed a frying pan and bent it like paper.
Chet’s eyes sparkled like a kid’s. “That’s what I need! With this, I’ll be unstoppable.” Wasting no time, he began training with the dumbbells, repeating the moves over and over. At the same time, the muscle man shouted instructions from the TV. He kept at it all afternoon, until exhaustion knocked him out cold on the couch, falling fast asleep alongside the other animals.
But not everyone slept so soundly. Soon after, a blue ear twitched among the beds, and Stu opened one eye, then the other, glancing around. Total silence. “Perfect” Carefully, he slipped out of bed and began sneaking toward the kitchen once again. The previous night’s adventure had awakened a new appetite in him, an emptiness in his stomach that neither breakfast nor lunch nor his pleading looks at Harvey had been able to fill. The human had refused to give him extra food. “Vet’s orders,” he’d said.
So there he was, creeping under the dim moonlight. His belly wasn’t as bloated as yesterday, but it was clear he had already widened a bit. “Just a little midnight snack,” he muttered to himself, as his paws carried him straight to the fridge.
Stu opened the refrigerator and didn’t hold back one bit: half a cake, cold cuts, sausages, half a tub of ice cream, and even a bottle of milk to wash it all down. Each bite puffed him up more and more until, with a satisfied burp, he slumped against the door, round and heavy, much fatter than the night before.
He waddled from one side to the other, his blue belly shaking with every step, bouncing against his legs. When he tried to get back into his little house, his sides got stuck in the frame, and he had to push several times to get through. Then came the struggle to climb into his basket, but in the end, he fell onto the pillow, sinking it under his new weight. Within seconds, he was snoring with a satisfied smile.
The following days were much the same, with Chet training from morning until night, following the VHS routines. Each day, his muscles looked thicker, his chest broader, and he even swore he was a little taller. But no matter how much he progressed, he still couldn’t lift the tube TV.
Stu, on the other hand, sneaked out every night, raided the fridge scraps or whatever he could find in the pantry, and returned to sleep with his belly a bit bigger than the day before. His body was widening, slowly but steadily.
Convinced the pup was sticking to his diet, Harvey proudly reported to the vet—until she saw that the blue dog was fatter than ever, his belly spilling over his legs. The doctor put him on a strict exercise regimen.
On the first day, Harvey supervised his cardio on the treadmill. Gasping and with his tongue hanging out, Stu came up with a plan: when he finished, he whispered to Chet that he should do the exercises for him. “The machine just counts the movements, right? Nobody will notice.”
Chet agreed enthusiastically. More training for him, more exercise to grow—and with a double shift, training in front of the TV, and running on the machine that was supposed to be for Stu, Chet’s body exploded in growth. His silhouette took on a T-shape: a wide, firm, powerful chest, well-defined muscles, and a gleaming six-pack that tightened with every breath. His legs, thick as columns, bore all the power of the yellow horse, and when he flexed an arm, a bulge formed as large as his own waist. He wasn’t far from the muscle giant on the VHS tapes.
Finally, the last VHS arrived. The muscle-man appeared on screen, giving his final advice in a thunderous voice “If you followed everything to the letter, you should have a strong, firm, and defined body… but you’re still far from my body of steel.” And to prove it, he posed, veins and muscles carved like rock. “Now you must repeat it all… but with even more weight.”
The screen went dark, leaving Chet sweating and thoughtful in front of the TV. There were no new routines to follow, but the phrase had stuck in his head: more weight.
With his new body, he lifted the TV once more. This time, he managed it, though it cost him. He’d barely set it down carefully when Harvey walked into the room and nearly had a heart attack, scolding him: “It could fall on you! You could hurt yourself!”
From then on, Chet was forbidden to use the television as a weight. He spent the afternoon scratching his chin, turning over in his mind what he could lift next that would be more challenging.
Then he saw Stu, spilling out of his own basket. They’d had to take the basket out of the wooden house days ago because he no longer fit through the door. Now his blue belly hung to the sides like a soft blanket, and with each breath his belly rose and fell like a bellows.
Chet’s eyes lit up. He grinned from ear to ear, thumped his own biceps with pride, and murmured to himself, “More weight… I’ve found it.”
Stu no longer needed to sneak around so stealthily. In fact, lately he barely moved and spent most of the day drowsy, only waking in the afternoon to eat something before collapsing again until night. When the other animals slept, he would get up—although that was no longer so easy.
His body had changed so much that he barely fit in the basket; the huge belly dragged along the floor with each step, producing a sway as he walked. It had been days since he had seen his own paws, though he could still feel them under that blue mass. His neck had disappeared, swallowed by a thick collar of fat, and a double chin dangled under his jaw, wobbling with every snort. His cheeks, round and tight, had eaten part of his peripheral vision.
But none of that stopped him. That night, he set out again on his slow march to the kitchen. He could no longer dream of climbing the refrigerator as before; now his world was limited to the low drawers and forgotten leftovers. He checked one, then another… empty. The last box of cereal had vanished the previous night. His stomach growled loudly, demanding food, and Stu could only rub his swollen belly with his chubby paws, trying to soothe the rumbles.
“What do I do now…?” he muttered in a tired voice.
It was then he heard a voice behind him “Need a hand, buddy?”
Stu tried to turn, but the mass of his body made him slow and clumsy. He could barely move his head before feeling a strong pat on his belly, which wobbled like jelly. It was Chet, looking at his friend with a grin from ear to ear.
“I’ve got a proposal,” said the horse, his eyes shining with excitement.
“Look, Stu,” he said confidently, “I’ve noticed your… substantial size increase. And that’s useful to me. I don’t have any more weights, so I thought, why not make you my new ‘training weight’?”
Stu’s swollen, blue cheeks flushed immediately. They had called him fat plenty of times as a joke, but hearing it this way—as if he were nothing more than a burden—pricked his pride. He was about to refuse when Chet, quick as always, grabbed his cheeks with his broad hooves, forcing him to look straight at him.
“And before you say no,” he added firmly, “think about this: I can help you feed that monster of a belly you’ve got. The fatter and heavier you get, the better you’ll be as a weight for me. What do you say?”
Stu froze. The mere idea made him uncomfortable—being treated like a thing—but his stomach growled so loudly that his soft belly vibrated. The dog lowered his gaze and thought. For days, sneaking around at night had been hard, and finding food in secret was becoming impossible. With Chet helping him, he wouldn’t have to suffer or crawl around the kitchen anymore; all he’d have to do was eat, eat, and eat.
The temptation was enormous. At last, he swallowed and muttered, “Alright… I’ll do it.”
Chet let him go immediately and let out a victorious laugh. “Well said!” he exclaimed, before giving the dog’s belly a firm slap that made it wobble like a giant blue flan.
With Chet’s help, Stu waddled to the food cupboard. Behind that door waited more supplies than the dog had ever eaten in his life. The horse, without the slightest effort, flung the cupboard wide open with a clang of the keyhole broken and began tossing cans, boxes, and food packets at him. Stu’s eyes gleamed with hunger as he lunged at each item like there was no tomorrow: whole cans, dozens of sausages, cakes, desserts… everything disappeared into his jaws.
The mountain of food dwindled until, panting and with his belly hard and swollen, Stu lifted a paw, begging him to stop. Chet smiled in satisfaction, hefted him onto his broad back like an enormous training sack, and carried him back to his basket. Before the dog slipped into a heavy food coma, he faintly heard Chet’s firm voice “There’s no turning back now, tubby.”
The next morning, Stu—basket and all—became Chet’s new personal weight. The horse, sweating and grunting, did squats, push-ups, and lifts with the massive blue bulk on top of him. His muscles throbbed and swelled, every fiber of his body answering the challenge.
When Viv and Chloe arrived, curious, Chet paused his routine to show them off. The stallion gleamed with sweat, his body a living sculpture, firm and defined, with a broad chest and a torso that commanded respect. The girls were fascinated, feeling his arms and shoulders, surprised at how solid he was. Even the red monkey, always sarcastic, had to admit, “I guess there’s no one stronger than you.”
But for Chet, that wasn’t enough. He only gave them a confident smile before plunging back into his exercises with renewed obsession.
Meanwhile, the vet was calling Harvey with a worried look. “You’ve got two severe problems here,” she said bluntly. “One, an animal morbidly obese… and another with extreme muscle development. Honestly, I don’t know what to do with either of them anymore.”
At night, Chet—now a living mass of muscle—cracked open cans and tossed heaps of food straight into Stu’s mouth, who could no longer move by himself. The dog had tripled his original height, but it was all fat—a blue hill of blubber that rippled and jiggled with every breath. His legs and arms were buried beneath layers of lard, but it didn’t matter: Chet was there to hold him, move him, and above all, keep feeding him.
Stu no longer saw the loss of mobility as a problem. He didn’t need to walk anymore; his world had been reduced to the pleasure of endless eating, with the certainty that there would always be more.
Meanwhile, Chet was reaching a new level of physical monstrosity. His muscles swelled beyond all proportion, surpassing even the size of the idol from his tapes. His body was a wall of tense, bulging fibers, shoulders like stone blocks, and arms as thick as tree trunks. With each passing day, he grew more and more until he was over five times his original size. His neck sank into the mass of trapezius and pectorals so that he looked less like a real horse and more like a statue of piled-up muscle.
There was nothing left of the little animals they once were. The “Little Pet” was gone. In its place, only two giants remained: one of endless fat and another of monstrous muscle. And neither showed any sign of wanting to stop.

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