Commission for Jack-The-Writer , who also wrote the accompanying story:

Shade the Echidna lay against the cold stone of the altar. The altar housed a gigantic purple emerald, the emerald she had been sent here by Knuckles to guard, the emerald of the sumo amazon village. She had been here guarding it for a few months, and already the effects of living here were beginning to show. The once thin and svelte echidna had bloated into an obese, engorged one. She was a fat shadow of her former self.

Not that she was complaining. She actually quite liked it. Although she did wonder how exactly she was supposed to defend the emerald from thieves in this state. But with the warm sun and pleasant weather, she couldn’t really be bothered to think about such things right now, and she began to doze off.

Rouge the Bat, a thief herself, was watching the fat echidna and the emerald from the top of a nearby hill through her binoculars. She watched as the echidna began to nod off until she finally fell asleep. She chuckled to herself, smiling. “Stupid fat echidna. How could she let herself go like that?” At the moment, Rouge seemed to forget just how big she had become. She was almost as big as the echidna herself, and her natural greed didn’t lend itself well to her slimming down any time soon.

With the echidna now asleep, Rouge decided to make her move. She’d been eyeing that emerald ever since she’d come to this village. And if it weren’t for Shade, she’d have stolen it a long time ago. But with that bloated guardian out like a light, now was the perfect opportunity. She would be the very picture of stealth.

But Rouge had forgotten that her size practically made stealth impossible. She flapped her wings, ready to soar down to the emerald, when she remembered that it would be impossible for her wings to support her massive bulk now. “Dang it… Guess I’ll have to do this the hard way.” She began to tiptoe down the hill as quietly as she could. Her fat made it difficult, though, jiggling and sloshing with every step she took.

Then she took a bad step. Her massive weight pulled her forward and downward, and she tumbled head over heels down the hill, landing at the bottom with a huge crash as her enormous rear slapped hard against the stone of the emerald temple. “YEOW!” She yelped in pain, snapping Shade out of her stupor.

She stumbled to her feet, still a bit groggy. “What… wha… ROUGE?!” Shade stared the fat bat down. “What are you doing here? Trying to steal my emerald?”

Rouge sighed. She was found out. She lumbered to her feet, smirking at the echidna. “Precisely. And if you’ll be so kind as to move your fat butt out of the way, I can get on with it.”

Shade balked at Rouge’s comment. “I have a fat butt? Have you even taken a look at yourself? My, my… you sure have let yourself go.”

A vein popped on Rouge’s forehead, and she lunged towards Shade. “Why you little!” Shade launched herself at Rouge to meet her, and they met, fortuitously enough, in the middle of the temple’s sumo ring. Their bellies met with a loud slap, as did their breasts, and they both brought up their arms and grabbed the others’ hands, each pushing against the other with all the force they could muster. They each struggled to push the other one back, but they were both so heavy that it was impossible to do so. They could both feel the other’s massive belly and mawashi pressing into their own, and their breasts were squishing together, pushing up towards their faces and stretching their tops. Their chubby hands grasped at one another, their fat faces inches away from each other.

Rouge growled. “You’d better keep your flabby hands off of MY emerald!”

“YOUR emerald?” Shade paused for a second, thinking about what she’d just heard. “MY flabby hands?”

Rouge smirked. “Of course! Once I beat you, I’ll be taking that emerald. And I’d appreciate it if you keep your fat little fingers off of it.”

Shade grunted, putting a massive amount of effort into her next push. “Not… likely!” Shade threw all her weight to the side, twisting Rouge and slamming her on the ground, a slam cushioned by Rouge’s copious amounts of fat. Dazed, Rouge just laid there, and Shade triumphantly planted a foot on her belly, said foot sinking into her belly fat. “I win!” She grinned at Rouge. “Better luck next time, fat bat!”