Author's Note

Having mulled on it for too long, I've settled on 3 different endings for this story. Let me know which ending scenario you like the most in the comments. The most liked ending will probably be getting a continuation from there.
Lemme know if you like ending A, B, or C the most!

Ending A [antidote failed]

The morning sun filtered through the trees onto a warm, wet earth below. Having a powerful rainstorm was just what the thirsty plants and trees needed. Many children and other foals were out and about playing already. Because of the accidental damages from whipping up such a storm there were crews out collecting debris and a call went out to delay all schools until 11am.

Applebloom took the opportunity to sit down and gulp some ice water. Yesterday was perhaps the most amazing, unforgettable day ever and some time to play mental catch-up was necessary. Thanks to due diligence a perfect potion was brewed to share with Rumble and thanks to Applejack, they’d accidentally drank each others intended drink, turning herself into a huge horny stud and Rumble into a small horny slut.

The antidote potion brewed last night seemed to not have worked. Applebloom leaned back in his chair and admired his body. He’d woken up fully male with quite the same body this whole mess started. For one she was much taller at an even seven-foot and had a build surpassing Big Mac. With little options available Applebloom had to swipe Macs’ clothing if he were to walk outside with a shred of decency. Unfortunately his big body was slowly but surely tearing Mac’s clothes into actual shreds. Already the biceps of the long sleeve had torn and there was the beginning of a split running down the back.

“Hey Applebloom, you feeling better?” Sweetie Belle approached from her left, conservatively dressed in a long skirt and a tight top buttoned up the front, carrying a cute umbrella emblazoned with her cutie mark.

“I feel much better, thanks,” Applebloom grunted, beckoning her over.

“Good,” Sweetie Belle closed the umbrella and took a seat next to her friend. “I hate to say it, but it looks like you kind of destroyed the restroom over-” she motioned to the ladies restroom, which had an out of order sign taped to the front, but cut herself off to look at her red-headed friend. “Applebloom? Is… that you?”

“Yeah,” Applebloom sighed, Sweetie taking a seat right next to her. “I took a potion that did this to me by accident. It’s a long story.”

“You look absolutely amazing!” Sweetie Belle whispered in quiet awe. “You’re like, the fantasy heroes in the romance novels I like to read. How big are you?”

“I’m like seven foot,” Applebloom reached up to scratch his head. “Maybe taller?”

“You might be even bigger than Terramar,” Sweetie Belle looked like she was about to start drooling, watching the football sized bicep flexing, and then her eyes traveled southwards...

An uncomfortable silence settled over the table as Sweetie ogled his body. “Oh there’s Scootaloo!” cried Applebloom, pointing at the sky.

Applebloom and Sweetie Belle waved as Scootaloo drifted to a landing in front of them.

“Hey guys!” Scootaloo stood up and placed her hands on her hips. “What’s up?”

Applebloom and Sweetie Belle gawked. “What the hay!?

Scootaloo was dressed up in clothes that were clearly a couple sizes too small for her. Every inch of her body looked like it was desperate to burst out of their stitched confines, from the thin T-shirt pulled taut over an overstuffed sports bra, to the way her jean shorts strained to contain her powerful thighs. It was obviously digging into her skin but the way Scootaloo was beaming at them she didn’t care one bit.

“Had a little growth spurt last night,” Scootaloo flexed her muscular arms and stretched, her hands high in the air, wings spreading out nearly ten feet from her back. “I’m pretty sure it’s all thanks to Applebloom here too. You’re looking big and buff by the way. So, I appreciate it. I’ve never looked or felt better in my life.”

Sweetie Belle had already stood up and walked over to Scootaloo. She was very obviously more than a foot taller. Her bottle green eyes barely reached Scoots powerful shoulders. “How tall are you now? Because I’m five-foot-six. Also why are you thanking Applebloom?” said Sweetie, wheeling around at her taller, stronger friend. "Can somebody fill me in?”

“I can help with that,” came a small voice from behind them. The three wheeled around and saw Rumble standing there looking a bit morose. She had also remained unchanged from yesterday. Rumble’s cute, heart-shaped face and wide violet eyes with thick lashes were framed by the long locks of dark hair that flowed down her back to the small of her back in big, thick braid, where her long tail swished over an ass so thick and wide it was straining the gym shorts she wore to the limit. Her soft midriff was on full display thanks to the phenomenal size of her chest eating up every inch of fabric available, and the too small shirt Rumble wore had the back tied in a tight knot, the only way to contain those breasts.

Those twin 32MM sized breasts were the definition of huge. Each one was more than double the size of Rumbles head and they were practically tearing through the tight blue T-shirt. Her plate-sized areola was practically transparent through the taught fabric and the nubs of her nipples made golf ball sized indentations. On her diminutive frame those breasts demanded all attention, and at that height everyone would be staring down at them during conversation.

“How long are you three going to stare?”

“Oh Rumble!” Applebloom stopped covering his mouth. “How short are ya?”

“I measured myself at 4’6” this morning,” she walked around the table to meet with the girls. Rumble was practically bursting from her clothes. It looked like any second her breasts would tear the shirt in half. Her shorts pants were so strained from the wide hips she sported that the elastic was frayed.

“You’re so much shorter than me!” Sweetie Belle ran over, enthusiastically comparing herself to the smaller stallion. “I’ve got almost a whole foot on you! And your boobs! Wow! I thought I was stacked… you look like you wouldn’t even fit in my F cups!”

Rumble practically whimpered and Applebloom coughed. “Uhh, listen girls, give Rumble a break. It’s been a rough weekend for the both of us and…” Applebloom shot a furtive glance at Scootaloo. “There’s lots of changes y’all gotta start dealing with until this is all fixed,” Applebloom’s thoughts drifted to the spell-book. “If it can be fixed.”

“Fixing schmixing!” Scootaloo strode over and put her hand on Rumble’s shoulder. “You two need to quit harping on my girlfriend or I’ll kick your asses!”

“Girlfriend!?” the two mares said in unison.

Scootaloo nodded, lifting Rumble up like she weighed nothing and engaging in a long, passionate kiss, their chests mashing together. Sweetie and Applebloom squealed in delight.

“You meant what you said yesterday?” Rumble said breathily, her violet eyes like fire.

“Every word of it,” Scootaloo said, ruffling her wingfeathers. “C’mon, let’s have breakfast and talk about our first date."