Celestial Growth Word

by The Irish Brony

Rating: mature
Tags: Sex, Profanity, Princess Celestia, Original Character, Porn, My Little Pony: Friendship is Magic, Fetish
Length: 3499

Celestia learns a new spell from her student twilight. She has a little fun with a friend of hers.

Celestia gets an interesting letter from Princess Twilight. One about a perverted Rainbow dash and a growth spell. Celestia is interested and decides to call on her best friend and student of science, Acid Flask, to test the spell with her.

Sex: Dick Growth, butt growth, male on female, macro on micro and macro

Published 2021-12-20 21:20:00 UTC
Last updated 2021-12-20 21:20:00 UTC

Prologue

In the Science wing of the castle in Canterlot walks a black pony with blue eyes, holes in his legs, bug wings, and faded-out fire symbol on his chest. The changeling walks down the hallway way till it reaches a door colored red. He opened the door and walks into a chemical lab. Test tubs with empty chemicals are thrown about with books being the next littered among the ground. In the corner is a short red pony hunched over with a flask in his mouth trying to pour it slowly into a test tube full of blue liquid.

The Unicorn was red with blue zebra stripes and orange eyes have a white lab coat and goggles on. His red and blue hair was spiked backwords as to not get in the way. His horn has a metal caller around the base. The top of the horn is bent backward. The unicorn sets down the flask and places the test tube back on the rack.

"Good Night Acid," the changeling says, slightly bowing to him.

"Dox," Acid says, turning around to look at the changeling as he pulls off the goggles. "You can call me Dad.." He looks at Dox confusingly. "And please stop bowing to me,"

"Sorry dad," Dox says, straightening up. Acid was taller than the little changeling, but not by much.

"What are you here for? I thought you had to head home," Acid asks, moving past Dox.

"The princess sent me to give you a message," Dox replies, fallowing Acid to the closet.

"What is it?" Acid asks, hanging his work coat and googles.

"She wants to meet you in her chambers," Dox says as the two walk to the door.

"Good, I'm heading out to file my paperwork, I can stop by and ask why she needs me," Dox pushes the door open and holds it for Acid. "Thank you,"

"I'll see you in the morning," Dox says, walking down the hallway.

"Technically, it's already morning!" Acid shouts down the hallway before heading towards Celestia's chambers. He hears an audible sigh from Dox witch makes Acid smile. Acid walks down the hallway and turns the corner to see a tall bat pony with red-eye, dark blue fur, and frazzled dark blue mane. She has her caption of the night guard uniform on. It's a dark blue shirt with a golden-winged pin. She is talking to a night guard as Acid walks up to them with a smile. The two ponies are mutch taller then Acid to the point where it almost hurt to look up at the two.

"For the last time, it's Firebrand's problem to deal with the day guards. Just go file a report and go home," the bat pony says with a hoove to her face. The guard saloots then walks past Acid Flask.

"Hello Moony," Acid says in a happy, kind of child like manner. She looks down at him and smiles.

"Hello Small Flask," She says, hugging him as Acid nuzzles into her chest. "Nice to know my husband didn't blow anything up yet,"

"Hay!" Acid says, pulling away, but still in her hug. "Moon, what do you think I am!? A freshman in Celestias school for gifted ponies?!" Moon looks at him with a raised eyebrow and a smile. The two laugh while starting down the hallway.

"So, what are you up to Flask?"

"Just going to Celestia," Acid pauses for just a second before resoming. "I didn't know why, but she want's me to meet her in her chambers?" They both look at each other consued.

"Do you know why?" Moon asks, almost hesitently.

"No, not really," Acid says as the two stop at a split in the hallway. Acid looks down the hallway to a big red door with two day guards garding it. Acid then get's and idea in his head. He turns around and loks at Moon scepitcly. "Why? do you know what she wants?"

Moon scoffes, "No, but if I had to gess." Moon leans into his ear. "She wants some of the Flask dick," This causes Acid to blush as little orange sparks fly out of his horn.

"Moon!" Acid yells in embarsment as Moon laghs. "The princess of the sun would never think like that!" Acid yells, but less loudly.

"Ya, I know." Moon says as she slowly walks away. She turns around to smile at Acid. "But rumer has it, someone with a small statur has a suprisingly big dick." Moon says while winking at him. She continues down the hallway, leaving Acid in a blushing mess.

"Luna damit Moony," Acid wispear to him self as he walks to the door. "Princess sent for me," Acid says to the guards. The two don't look fazed as they open the door with their magic. Acid walks into the big room as the doors close behind him.

Celestial Growth Word

Acid Flask stands in the middle of Celestia's room. Her giant bed sitting across the way from the door. The room was circular, with a few bookshelves and a desk lining the outside of the room. To his left stands Celestia looking out on her balcony. Her majestic hair and her pure white coat make Acid feel skittish. The two have known each other since he was seven, but he still feels wrong around her. He always thinks to himself, "Why did she ever choose me as a student?"

He starts to walk over to Celestia as his eyes, against his own will, trail down her back and straight to her butt. Her plot was the biggest he has ever seen. Nice and plush, and with that beautiful sun cutie mark showing off her nice curve. He shakes his head while trying to remove the image of her magnificent butt. He stops next to her and looks out into the city. She is unfazed by his presence.

The two stand there, admiring the slow sunrise Celestia was bringing up. She smiles as her magic washes over Acid Flask's body. Acid Flask smiles and returns the gesture to her. The two let each other go from their magic hug before Celestia talks in her sweet and silky voice, "Nice to see you again Acid,"

"Nice to see you to Tia," Acid says a little bit more wavery than he would like. He smiles up at her as she looks down at him with a kind smile.

"Do you know Twilight?" Celestia asks. Acid scoffs at the questions.

"Who doesn't?" Acid replies. "I never got to know her, but being your student, we both ran into each other from time to time," Then a question popped into his head. "Why are you asking?"

Celestia chuckles as she turns around to face Acid properly. "My former student Twilight has accidentally found a very.. interesting spell." This intrigued Acid, he raises an eyebrow in anticipation. "It was a growth spell that can cause pleaser to the user. I thought I would ask my closest friend if he would like to try it out with me?"

Acid's face goes from happy to shock, his ears flopping against his head. "Did the princess just ask me to have sex with her?!" The first thing that pops out of his mouth is. "Is Blood Moon ok with this?" "Why am I even asking!? I should leave right now,"

"Don't worry, I already talked to her about it," Tia responds calmly. Acid shakes his head back and forth as his head floods with so many questions.

"No, I don't think I can do it," Acid says as his horn glows orange. With a pop and a flash of orange light, he disappears. Celestia chuckles and walks slowly over to the bead.

"He's not going to get far," Tia thinks while looking at the caller that usually is around Acid's horn, now sitting on her bedside table. In a few seconds, another pop and a bright flash of light, Acid reappear on the bed.

"What?!" Acid says, looking around, confused. Celestia smiles as she watches Acid look at his horn caller on the nightstand. His dick out of its sheth and half-erect already. "You bitch!"

"Is that what you call your friend?" Celestia asks insulted but with a child-like grin on her face. Acid looks at her angrily. The two stare at each other before Acid sighs and sits down on the bed.

"Fin," Acid says reluctantly. "but make this quick,"

"Looks like your dick goes against your feelings," Celestia chuckles as she sits down in front of him. His throbbing cock is almost the same length as his body and almost the same thickness as his muzzle.

"So," Acid asks, relaxing. "Do you need to cast the spell?"

"Nope," Celestia says, rubbing his dick slowly. Acid closes his eyes and grunts in pleaser as he feels her soft fur rub against his dick. Acid's eyes snap open in epiphany.

"You slipped the spell in during our greeting!" Acid yells. Celestia smiles sweetly at him.

"Nice to know you are still smart," Celestia says before taking a big breath and explaining. "I put it on both of us, it works when a trigger word is said."

"So what are they?" Acid asks, slightly impatiently. Celestia chuckles before continuing.

"Yours is Flask." Almost immediately, Acid's body is wrapped in a white area of magic. He grunts as pleaser runs through his body. He smiles as his eyes and mouth relax. The magic stops, leaving him a foot taller than normal.

"That was heavenly," Acid says, still entranced.

"Mine is Sun," Celestia says, before being wrapped by the same magic as Acid. She stands up so Acid can see the hull thing. She closes her eyes as her plot grows to double its original size. Acid watches in awe as her flank grows, causing his dick to let out pre-cum in excitement. Celestia opens her eyes to see Acid looking at her plot.

"You can say the sun has risen?" Acid says with a cheeky smile. Celestia closes her eyes and lets out a light moan as her butt grows again. It is now completely visible from where Acid sits.

Celestia opens her eye halfway and looks at Acid. "Looks like somepony got in the mood quickly." She rubs her face against his throbbing dick.

"It's kind of hard not to be when watching your royal butt grow." Acid lovingly places his hoof on her cheek. She smiles at the touch before she gently pushes him back and opens his legs.

"Let's warm you up first," Before Acid can respond, Celestia takes in his entire dick into her mouth. Acid shuts his eye hard, moaning as his legs twitch from her warm mouth. Celestia looks up and smiles as she watches her student twitch from her touch. She starts to thrust up and down his large shaft as she licks her tongue against the side of his dick. Acid's mind is flooded with pleaser as he thrusts his hips into her mouth on instinct. She chuckles as she speeds up her thrusts. Acid slightly recovers as waves of pleaser still wash over him.

Acid chuckles before saying, "I guess the Sun is sucking off a giant Flask." The two moan in unison as the magic washes over them. Acid pants as he grows taller and his dick grows thicker and longer. He watches as Tia's rump grows bigger and wider. He imagines rutting her plump rump as the familiar sensation starts to build up inside of him. The two stop growing as Acid grabs Celestia's head and thrusts small but hard thrusts into her head as he moans. His cum coated the inside of her mouth and throat. She relaxes as it happens. Acid finally stops and falls back onto the bed. Celestia pulls off and swallows the cum as she licks her lips.

"You ok?" Tia asks.

"Ya, just took it out of me," Acid says, rolling onto his side to look at Tia. Celestia closes her eyes as she feels the magic take over her goddess-like body. She lets out a quiet moan as her butt and body grow. Acid watches as her rump grows to the size of two fully inflated beach balls. His dick hardened again. He looks down and sits up in confusion.

"how am I hard?" Acid asks.

"The spell allows the stallion to have more than one orgasm," Celestia explains. Acid is unable to respond before Celestia sits on his lap, crushing his dick between him and her plot. "Now lay down so I can keep warming you up for the BIG stuff," Acid doesn't argue and lays down as Celestia sandwiches his dick in between her heavenly cheeks. "Time for the sun to rise again," Celestia chuckles at her own joke before her but starts to grow again. Acid sighs as her butt consume his dick in her soft plump rump.

Celestia slowly starts rubbing her butt up and down his shaft in a butt job. Acid shivers at her butt, gliding smoothly up and down his dick. "The sun rises, but so does my.." Acid moans before continuing. "Flask's dick." The two shivers and moan as the two start to grow. Acids dick starting to barely pock over her plot. Celestia's butt starts to grow bigger, taking up most of Acid's visions as the two start to grow bigger.

"Flask's sun, that sounds interesting," Celestia says aloud. The two moan again as Acid starts to become to big for the bead and as Celestia has to bend over so as to not hit her head against the ceiling. The growth and the majestic plot on top of him cause him to go over the edge. Acid grunts and yells,

"I'm cumming," his hips thrust up as cum pulses out and lands on Tia's butt.

"Cum on me big boy," Celestia says, still moving her butt up and down his cumming dick. Acid finally stops as the cum disappears and turns into white magic. Tia's butt starts growing at an alarming rate as so does her body. Her butt covers everything but Acid's head as she grows to fill the room.

"Looks like somepony is getting too big," Acid says, hugging her plush, giant butt.

"Let's finish this outside," Celestia says, teleporting the two outside. They land in the snow on the side of the mountain. Acid shivers for a second before Celestia's warm magic washes over him.

"Heat spell?" Acid asks as the two stand up. Celestia towered over him, with her giant butt being the main attraction.

"Correct, but I think if you want to rut my Flask, you're going to need to be bigger," Celestia says with a smile. Acid blushes as the magic takes over him. His dick was now longer than his body and almost as thick as his legs. His body grows taller, now only just a head shorter than Tia. "Mabey one more time Flask?" Acid shivers from pleaser as He grows taller. He is now ahead taller than Celestia, his cock pocking her in the chest. She looks down at his cock as she rubs her hind legs together.

"Now time for the fun," Celestia says turning around and pressing herself against the ground. She pushes her butt up into the air. Acid can't help but look at her glorious big majestic plot as his dick hardens completely again. Acid wordlessly gets on top of her and lines up his dick with her slit. He gently slides in his dick, causing a light moan from Celestia.

"Ready down there sun butt?" Acid asks with a smile. Celestia moans loudly as her butt and body grow again. Her butt becomes the size of her room as her body tries to keep up with her rump. "I need a kick of Flask before I start now," Acid says, his dick now at a painful 65-degree angle as he is now shorter than her. He moans as he grows taller and his dick grows bigger. Once he can safely lean over her plot he starts to thrust into her.

She shivers and grunts in pleaser. Her royal rump giggling with every thrust of Acid's big dick. "You could say The sun has found its Flask," Acid says through moans and grunts. Tia basically crumps to the ground with only her plot held high. The two starts growing again. The two moan in unison as Acid's dick grows inside of Tia with every thrust. Her rump grows to almost the size of her castle. The two Grow taller than the mounted in front of them. Canterlot castle now clearly in view. Tia pushes her face against the face of the mount as Acid picks up his thrust.

Her rump and body giggling with every powerful thrust as the build-up of both of them start to become too much. "Show me how much you worship the royal sun butt," Tia says through grunts and haze. Her plot grows again as it starts to surround Acid's hips. She grunts as he thrusts hard into her and stays there.

His cum sliding into her causing her to grow even more. Her plot now surrounds Acids as her body gets bigger than the mountain. Acid quickly slides up onto her now mountains rump as to not fall down. The growth slows down to a stop as the to lay there in the morning sun.

Epilogue

Blood Moon the bat pony walks into Acid Flask's lab. Acid is in his lab coat with his goggles pulled over his eyes as he tinkers with a little collar. It is black with a blue orb and light blue grid wire patterns. Moon is wearing a red scarf around her neck and not her caption uniform.

"How is my little scientist doing?" Moon asks, wrapping a hoove around his back. Acid places the collar down carefully with his magic and pulls off his goggles. He looks up at her and smiles.

"I'm doing good," Acid hugs her back as best as he can. "How was your night?" Moon sighs in frustration as she pulls him close. She sits down with Acid looking at her worryingly.

"Firebrand's Day guard keep disappearing, breaking royal property, or harassing my night guards!" Moon yells in anger. Acid lays down in her lap as Moon starts to pet his head. He nuzzles into her and licenses as she vents. "Bouncer keeps bumping into shit! I keep telling Firebrand to take him out of duty for training but he will not listen! and don't get me started on Crystal!" Moon vents out her frustration as she continues to brush Acids spiking and wild mane with her hoof. She finally stops and takes a deep breath in and sighs. "So.. how was your special day with Tia yesterday?" She says, emphasizing special.

Acid snaps out of his trans and stands up suddenly. He points a hoof at her before saying, "You knew, didn't you!" Moon chuckles and nods yes. Acid lowers his hoof and looks at her with a pout. "Why didn't you tell me?"

"because you would have avoided it at all cost," Moon explains as she stands up. "You really need to let loose, so I asked Tia if she could help,"

Acid blinks a few times before turning towards the collar on the table. "So that was a coincidence," He says into his hoof as he thinks. Moon tilts her head in confusion.

"What is it Acid?"

"Tia showed me a growth spell that could be useful to our own sex life." Acid explains. Moon looking over to the collar on the table. She smiles and nods as she connects the dots in her head.

"You're making a sex toy?" Moon says with a big grin. Acid turns back to her with a beat red face. Not like it could get any reder.

"If you put it that way it sounds bad," Acid says as Moon laughs at his embarrassment. "There are still a few problems, but maybe for once I can show you a good time,"

Moon stops laughing and smiling down at him. She ruffles his hair as she says, "It would be a nice change to have that big dick of yours fucking me instead of me having to do all the work."

"Stop that!" Acid says playfully as he slaps her hoof. "We need to go pick up Midnight from school before she thinks we forgot her," Acid says, sliding his lab coat off and placing it and his goggles into the closet.

"And so Dox doesn't have to deal with her," Moon says. The door walks out of the door, as it closes Moon bumps her butt against Acid's side. He stumbles a bit before looking at her with a pout and a blush. Moon starts to smile, and so does Acid as the two hugs and laugh as they walk down the hallway.