Enjoy the random silliness - Prompted from this post and image - https://desuarchive.org/mlp/thread/38880815/#38910840

>Spike reads this edition of Power Ponies and develops the macro pony kink
>proceeds to keep having thoughts about the real Rarity being that big, to the point he struggles to sleep without drooling about his crush, amplified
>one day, he stumbles on Twilight trying to use a spell to enlarge the foodstuff of a struggling settlement as a stopgap until the nearest town can send food, namely the towns meagre oat harvest
>strangely, the oats seem unchanged when she casts the spell on them
>frustrated, Twilight decides to go for plan b: simply teleport more food there, so leaves to make the preparations
>Spike then notices the oats shimmer and glow, and the grains seem to enlarge ever so slightly
>dreaming big (pun absolutely intended), Spike takes the pats and bakes up some oat cookies
>he then hurries over to Rarity’s place
>of course, shenanigans occur; Pinkie pilfers one cookie, Applejack bags one as well, as does Dash as she snatches one in flight
>but, finally, he makes it to Rarity’s boutique
>touched by the gift, Rarity enjoys a cookie
>and, at his pleading, he stuffs two more in her muzzle
>minutes pass, and nothing…
>they’re suddenly both surprised as Rarity’s stomach rumbles louder than Pinkie’s after being refused sweets for a whole day
>but not as surprised as when there’s a literal rumble in the earth, to which the pair head outside
>a thick, curly pink mane sprouts out of Sugarcube corner’s window
>followed by the hooves of a lighter pink mare, then the rest of her who looks around in surprise, now as big as the building once was
>in the distance, Sweet Apple Acres is suddenly dwarfed by Applejack as her hooves knock aside several trees, launching them in all directions
>lastly, a massive shadow blots put the sun as a gigantic blue mare falls to earth with a massive quake
>Rarity stares, slack-jawed at this, before her stomach roars again
>then she grows
>and boy does Rarity grow
>her ass crashes through the boutique
>her forehooves crash into the opposing buildings
>she stumbles, trying to get distance from Ponyville, but her ever-lengthening legs make it difficult
>then as the second and third cookies do their thing, she slips back, sprouting to gargantuan size in the blink of an eye as she falls
>her tail lifts, and the great, now Ponyville sized ponut of Rarity takes up the sky
>Spike gasps
>then just raises his arms
>closes his eyes
>and and smiles in resignation as Equestria, no, the whole land feels the mighty impact of the colossal fashionista

*This part was done by another anon
>closing his eyes, spike fails to see his platter of oatmeal cookies being teleported away
>"just one more," rarity tells herself, but quickly empties the entire plate of delicious cookies one by one
>her stomach begins to roar

*and back to me*
>Spike suddenly snaps awake
>just a dream... maybe
>he looks out the window at the wreckage of Sugarcube corner, and a few other buildings didn't fare well at both the trees launched by Applejack and Rarity's attempt to escape Ponyville
>*that* certainly wasn't a dream
>but Rarity eating more cookies didn't happen... damn it
>Twilight just barely managed to perform an amazing feat of magic by creating a barrier over Ponyville, while the rest of Equestria was still repairing the damage from the country sized quake caused by Rarity's ass
>Spike climbs out of bed and helps out with repairs before Twlight gets on his case
>of course, it wasn't just the damage that remained
>the oat cookies, while mostly cured, were stubborn
>a subtly bigger Pinkie and Applejack are hard at work
>as is a larger Dash, flying in more building materials and keeping the skies clear
>Rarity, however, is now as big as Big Mac
>she glances at Spike and... did she just lick her lips?
>whatever, there was work to do
>hours of hard work later...
>"Spike, darling... I'm just absolutely *famished*"
>uh huh
>"I don't suppose you have anything to eat?"
>not on him...
>"Oh, well, I just have the most intense craving for cookies..."
>wait, what?
>she begins biting her lip and pacing before snatching him in her forelegs
>"I need it, Spike! All those eyes on me! The sheer expanse of my body smothering everthing in sight! Please!"
>Spike has no idea where they went
>he thought they were teleported away, but he couldn't remember if that was a dream or not
>"We could make more, right?"
>is that such a good idea?
>"Spike, I shall speak plainly; you obviously wanted me that big, I *also* now wish to be that big and respendant. Whatever it takes."
>Spike considers it for a sec-
>yes
>that night, Spike locates the book Twilight used with the expansion spell
>he then sneaks out to Rarity's place, where she's got the oats ready for Spike's cookie recipe
>but when checking the book, Rarity pouts
>"This is... very advanced magic, Spike. I don't know if I can cast it."
>it was Spike's turn to be insistant
>he *needed* to be smothered by her ground-shaping ass
>"You're right... we can but try."
>she strained as her horn glowed, then the oats
>and she continued to struggle as the glow intensified
>eventually, she all but collapsed, breathing hard and heavy
>she was spent, and they had no way of knowing it had worked
>so Spike got to baking
>and before long, there they were, a fresh batch of (potentially) growth-inducing oatmeal cookies
>Rarity didn't wait for them to cool
>she popped on in her mouth, yelped at the temperature, but chewed and swallowed the treat
>then, winking at Spike, took two more
>and then they waited
>and waited
>Rarity's stomach gurgled, and they both stared in anticipation
>but... nothing?
>a knock at the door
>"Rarity? Is Spike in there?"
>it was Twilight!

>Spike panicked, as did Rarity
>"I'm missing a spellbook," Twilight continued. "The one that caused all this mess. Please tell me you're not making those cookies again!"
>"Quick, hide," Rarity said
> Spike grabbed the book and cookies, then went toward the closet
>only for Rarity's stomach to gurgle more intensely
>and, with a subtle moan, her body shuddered and grew
>it was far slower than last time
>Twilight continued, "what's going on in there?"
>now they both had to hide
>Rarity and Spike crammed themselves into a cabinet as the mare continued to slowly swell larger
>"Oohh... it feels so *good*," she whimpered as the cabinet became increasingly cramped
>Spike pushed himself as far back against the wall as he could
>even as Rarity's growing ass approached
>then the dark cabinet glowed blue as she picked up more cookies with her magic
>what the hell was she doing, Spike pleaded
>"Shh," Rarity complained, and popped a few more treats in her mouth
>Twilight opened the boutique door and paced around
>they heard her head upstairs
>as soon as the sound of hoofsteps grew distant, Rarity moaned loudly
>and pressed her now Celestia sized ponut in Spike's face and moaned even louder
>Twilight came running down stairs
>"I heard that! Where are you!?"
>Rarity held back another moan as she crouched down, and bit the door handle
>and just in time as the handle glowed pink and tried to turn
>"What... are you in there?"
>there was a pink flash around the doorframe
>"Wait, why can't I teleport in there? That only happens if there's not enough room... oh. Oh no."
>Rarity shuddered as the mounting magic inside her made her growth accelerate
>she soon took up the whole cabinet
>the door creaked and groaned
>then burst as an elephant sized Rarity tumbled out
>Spike gasped for breath, Twilight in shock
>she then scowled at the little dragon
>"I warned you not to do this again! Where are the cookies?"
>Spike sheepishly looked back inside the cabinet
>and saw the plate
>completely empty
>Rarity giggled, then crunched
>both Spike and Twilight stared at Rarity as the last of the treats vanished down her throat, and she gave the daintiest of belches
>"Forgive me, but they were just *too* good to waste."
>Rarity's stomach visibly trembled with the gurgling within as her growth increased in pace once more
>"Okay, that's enough," Twilight growled, and cast a spell
>Rarity shrank back down, now seemingly stuck at Celestia's size
>"I think I'll go hide this book somewhere it can't cause any more mischief."
>Spike gulped and poked the purple pony
>"Wha... oh, for Celestia's sake."
>Rarity smirked as her body trembled, and grew again, though at a much slower pace

>So Twilight cast the shrink spell again
>...then, after about a minute, Rarity began to grow again
>it soon became apparent Rarity was permanently stuck growing
>and, try as she might, Twilight couldn't keep shrinking her as the spell was too intensive
>so eventually they just set a routine, once they made an equally giant tent for her larger sizes
>Twilight would shrink Rarity back to her splendourous princess height once every three days, roughly when Rarity's hooves began to caused tremours felt in Canterlot
>and as a wise mare once said, if you make a bed you have to sleep in it
>which is why Spike only slept in Twilight's place one day out of three
>the other two, he spent jammed up Rarity's holes
>which one? Whichever they wanted, though she always had last say
>and they lived growingly ever after
And that'll do for that.
I'm sure you can imagine a time when Twilight loses her powers or gets captured and Rarity's *sadly* forced to grow until she can once again smother Equestria under her gigantic ponut