Size difference for the whole family!

Isaac felt like it was time to take charge. Granted, usually he fine being a pretty passive, laid-back guy – hence all the reality changes that primed this world to initiate lewdness for him – but he also enjoyed having the right to veto and assert himself whenever he wanted – hence all the Master/**** dynamic stuff. The ultimate lazy tyrant's privilege.

So he stepped out of line and walked up to the counter past all the other customers, undid his pants button and zipper, hauled out his already mostly erect cock, and let it fall onto the counter with an audible smack that would've caught the attention of everyone in the shop had it not already been captured by his presence. Nonetheless, it still had the effect of quieting all the chatter and forcing everyone to patiently listen, like he'd slammed the gavel in a courtroom. It was an immediately powerful feeling.

Isaac looked over his shoulders at everyone in the room. "I'm here to fuck Pinkie Pie. And while I'm here, I might as well have an orgy with the Cakes as well. So Sugarcube Corner is going to be out on a very long lunch break today. No one has a problem with that, right?"

Pinkie Pie let out an "Oooh!" as she stared at his cock with open-faced delight. Pumpkin Cake blushed heavily at his cock being so close, her thick nipples trying to escape from the sides of her apron. Mrs. Cake gasped and put her hand over her breasts like her heart was fluttering. Mr. Cake seemed to be practically bouncing with excitement. From upstairs, Pound Cake yelled, "Wait, what did he say??"

The other ponies in the shop prepared to leave with their pastries, though some of them approached Isaac with offers to join in, as well.

"I know my tits aren't as big as Mrs. Cake's, but I'd love it if you fucked them!"
"Dude, I'll suck your dick and be your fluffer between rounds if you want."
"Can I watch? I'll just sit in the corner – you won't even notice me, I promise!"

Isaac put up his hands, even though most of them were behind him while his dick was on the counter. "Look, I've made my decision. I get the final say on who joins me." Thankfully, the ponies all nodded in understanding at that. "But..." Isaac added, "you can wait outside and listen for the telltale sounds of the orgy if you want..."

That seemed to be agreeable with everyone, and one by one they started filing out of the bakery. Isaac let out a sigh of relief, and then... Pinkie Pie reached over the counter and grabbed his hand? "C'mon, let's get the party ready while the Cakes close up shop!"

Suddenly, Isaac was yanked over the counter and up the stairs at a frankly irresponsible speed, somehow without bumping his legs on any hard corners. They passed by Pound Cake hovering in the second-floor hallway, in the middle of pulling up a sleeve onto his cock, before climbing up the second flight of stairs into the large attic that Pinkie Pie used as her bedroom and personal event space.

Unceremoniously, Pinkie Pie plopped him onto the side of her bed, his pants and underwear having dropped to his ankles from the **** of travel and his cock still bobbing in front of him for a few seconds. Then she unexpectedly gave him a big hug. Her ultra-soft breasts and belly smooshed against the front of his body, pressing down on his dick and covering everything from his neck to his lap in warm bubbly comfort. It was a simultaneously relaxing and arousing **** of sensations.

"Thank you so much for showing up and fucking us all!" Pinkie Pie squealed excitedly, her legs bouncing in alternating rhythm and making her rump jiggle. "Mm, and I can smell Twilight and Dash on you – good choice! I would've thought you'd take Rarity or Fluttershy next, but I'm not complaining!"

Isaac tried to hug back, but he could barely manage to reach up to her shoulders from the way she was squishing down on him. "Twi said... you deserved to know that you were right..."

Pinkie Pie pulled back with a gasp and a big open smile. "So she thinks that you're the one?? And she sent you to me?? Oh, that is SO sweet of her! And you, you didn't have to, you're the potential Master and all, you don't even know me or my Pinkie Sense, but you felt like doing what she asked! Oh, you two are so nice I'm gonna explode from kindness!" She then let go of him and stood up, her tits and belly jiggling after they stopped smooshing against Isaac's body. "I'm gonna go set up the party decorations, so you just sit tight and think horny thoughts, okay?"

She didn't even stop for a confirmation before she was off, bounding around the room, setting up streamers, blowing up balloons, setting out tables with... arrays of dildos on them? Isaac wasn't sure why a quick impromptu orgy needed party decorations, but he knew better than to ask. And he was grateful for the moment to think, anyway.

But god, Pinkie Pie was a wonder to watch in motion. Totally naked, every massive curve jiggling with every step and bounce... Isaac wasn't usually a big fan of the zaftig body type, preferring hourglass figures most of the time, but damn if Pinkie wasn't making a strong case for it in the way she moved! The fact that she was not only thick but a little taller than him inspired some strong ideas, too...

Size difference had been on Isaac's mind for a while. He really liked being overwhelmed and overpowered by abundant sexuality, and he wanted a bit more of that in general. But he also liked size difference in the other direction – Isaac was craving some shortstacks. And seeing the freshly adult twins had given him an idea for a change, one that he could mutter under his breath while Pinkie was giving him some space...

"Is it true... that sapient creatures native to this world take a longer time to grow up to their full height, with, for example, the average adult pony being three feet tall by age 18, six feet tall by their mid-to-late twenties, and leveling out on average around nine feet tall by their late thirties to early forties?"

In an instant, the room grew. The very concept of architecture had to adjust for all the ponies being at least 50% taller than usual. Even the bed Isaac was now sitting on had plenty of room for Pinkie to grow.

Pinkie Pie hadn't grown by much, maybe only a couple of inches. She was around Isaac's age and thus around his height, but she also had a 'big' body according to his previous change. Amazingly, she looked smaller in comparison to the attic now, having to bounce up to stick streamers to the top of the walls. It wasn't until she jiggled closer that he was reminded that she still had a foot and change on him.

Once again, the power trip had him just as rock-hard as the casual sexuality, imagining how the entire world had changed as a result of his question. When he returned to Canterlot, would the alicorns be even taller now? He hoped so!

Actually, now that he thought about that, Isaac realized with a quick glance down that his balls were a lot fuller and bigger, hanging down lower to the ground. His cock had swelled up a bit thicker to compensate as well. He realized after a few moments that he'd asked if he was going to cum enough to make Celestia look pregnant... which now retroactively required more cum. So his balls and loads had retroactively grown. Which meant that past questions could be recontextualized by future questions to keep their answers remaining 'Yes.' That was a little exciting and troubling.

With side-effects on the mind, Isaac realized there might be a couple other problems with his recent change as well. "Is it true that, despite any height difference, everyone generally treats and respects young adults as adults, never as youngsters who need to be coddled? Is it true that the sexual characteristics of sapient creatures grow in a fair bit faster than their height, always growing at least a tiny bit each year until their height finally plateaus?"

"Alright, store's all closed, we're coming up!" Mr. Cake called from the stairs below, his voice booming a little louder than before.

One quick hop later, Pinkie Pie had finished sticking the party decorations to the walls of the attic. The big open room was now fully furnished for a real party. She turned around towards the stairs, her tits and ass somehow a little bit bigger than before, wobbling in greater degrees. "We're just about finished up here! Come on up!"

Isaac watched in anticipation as he heard several sets of footsteps coming up the stairs.

Mr. Cake was the first one to arrive, his excitedly grinning face emerging, then his neck, then his long torso... Being among the older set of the group, Mr. Cake had turned into a tall, lanky mini-giant, his long legs pushing him high above Isaac as he reached the top of the stairs, smiling down at him and Pinkie. His still sleeved-up cock still hung down to his ankles, which meant it had to be somewhere in the range of four or five feet long, nearly half of his height.

Mrs. Cake came up behind him with a brief delay, her body being a bit stockier but no less gigantic compared to Isaac. Her giant blue tits looked even more gigantic, and her pink nipples were still dripping milk, mere drops compared to the gallons she must contain. But they overshadowed her lower body less now, which gave Isaac an opportunity to appreciate how wide Mrs. Cake's hips were, just screaming 'fertility' and 'motherhood.' She leaned up to Mr. Cake's cheek and kissed him before looking down at Isaac hungrily.

Then the twins came up, one after another, one walking and one flying with his wings. Being fresh young adults, according to Isaac's new changes, they were now merely a third of their parents' height, give or take. They had to get around Mr. and Mrs. Cake's legs to be seen.

Pumpkin Cake was a true shortstack now, about half of Isaac's height but with massive tits covering down past her waist. She stared at his hard cock with a daunted look on her face – and why wouldn't she, facing a cock that was almost as long as she was tall?

Pound Cake hovered up and perched on his dad's shoulder, looking down at Isaac with a deep blush. He was now a male shortstack for sure – toned, lean, with a heftier than usual ass and a long cock dangling between his legs that he didn't seem too bothered about using.

Giggling excitedly, Pinkie Pie bounced over to the Cake family, standing in front of the married couple and their twins, hands proudly on her hips as she inadvertently presented herself as an example of the middle ground between shortstack and amazonian. "So! Isaac! It's your party, so how do you wanna play first??"

Isaac couldn't help rubbing his hands with glee.