The Princesses's Late Night Ballooning

“Come this way, Sister,” a fat midnight blue alicorn says as she trots onto a field, her fat belly dragging on the ground. “Luna, I should be getting some sleep right now, but it would be nice if you could tell me why we are here?” a white, tall slender alicorn asks.“Oh, I was just hoping we could have some nightly fun, Celestia,” Luna responds with an innocent smile. Even though Celestia is feeling tired, it has been awhile since those two really had spent some quality time together.“Alright, Luna. What did you have in mind?” Celestia asks. The obese Princess of the Night smiles with glee and claps her forehooves together in excitement.

“Okay, sister. Close your eyes, first,” Luna says. Celestia closes her eyes slowly and begins to wonder what Luna is planning. A mischievous grin forms on Luna’s face as her horn begins to glow with magic. An anti-magic ring, surrounded by a dark blue aura, rises from her behind and flies over to Celestia. The ring inserts itself through Celestia’s horn until it reaches her forehead. “Now to start the fun,…” Luna whispers to herself, using her magic to grab another object. Nearby, a group of bushes begin to rustle and shake until a hose and a compressed air tank come out. She slowly levitates the air tank near her sister’s flanks and sets it down. Luna licks her lips as her magic holds the hose up just a bit above Celestia’s lovely rear. Soon, she shoves the hose straight into her sister’s tailhole and causes a loud yelp to come out of her mouth.

Celestia quickly opens her eyes as one of her rear legs twitches a little. “Luna, what did you do?!” she questions before hearing a subtle hissing sound. Celestia quickly looks back to see the hose in her butthole until she feels her tummy fill up. Her once slim, white belly starts to expand outwards slowly as if she had eaten dinner twice. Celestia bites her lower lip and settles one of her hooves on her expanding belly. “I-Is this the game you wanted to play Luna?” Celestia nervously questions as her fat sister replies with a nod. Sweat drops begin to form and drip from her forehead as she shivers from the sensation of her belly inflating outwards. Just before her belly is about to touch the ground, Celestia shakes her head. “L-Luna, I don’t think I can p-play this game with you,” she says as she attempts to use magic to remove the hose. She closes her eyes tightly and clenches while attempting to cast a spell, but the ring refuses to allow such a thing.

“Awwwww...Sister, I should have told you that you aren’t allowed to use magic. It’s punishable. So as punishment,...let’s increase the pressure!” Luna shouts excitedly, using her magic to grab and turn the valve of the tank further. Celestia feels the pressure rise before the air starts to push out into other places.

Her smooth rump begins to billow out like two balloons while her thighs and forelegs start to thicken and fatten with air. Celestia pants a little bit until she feels her neck and cheeks expand as her once tall, slim figure becomes more plump and swollen like a fatty, but with hardly any weight. “I-I need to stop this n-now!” Celestia grunts as she tries to reach for the hose with one her fat forelegs. But her leg could hardly reach and her balloon asscheeks keep expanding while sealing the hose in place.

“Tsk, tsk, Sister. You shouldn’t be trying to take the hose out until I say it can be removed. Looks like you just earned yourself more air,” Luna comments, shaking her head as her horn glows with magic once again. Celestia gulps and watches her sister turn the tank’s valve further as the hissing becomes louder.

Celestia clenches her teeth as the airflow skyrockets. “I’ve got to get out of here,” she mutters to herself as she feels herself continuing to expand further. She feels her belly push against the ground below as it starts to lift her up. Her back grows and billows out. She flaps her wings for a second and she immediately gains an idea. She can fly up and away from her plump inflator. Celestia smirks as she tries to flap her wings once again, only to feel them stiffen suddenly. Her wings shake for a moment before they inflate as her feathers swell like balloons. “N-No! C-Come on!” Celestia shouts as she tries to fly, but her new puffy wings can barely move fast enough, making squeaking sounds like a chew toy. All the while, Luna howls with laughter at the sight of Celestia’s new wings, her sister blushing in embarrassment.

“Oh ho ho! Never thought you or your wings would look so good being so blown up! I should have done this long before!” Luna laughs, hugging her fat blue gut. Celestia glares at the laughing pig as she starts to feel her hooves sink a bit into her swollen limbs, along with her head pulling into her bloated neck. Celestia begins to worry upon seeing how large she has truly become. Luna soon gets up and observes her blimp of sister, who is just a little bigger than a Ursa Minor now. Luna trots behind her balloon to marvel at those two massive, white weather balloons for buttcheeks, which easily help hold the hose and prevent it from slipping out. Below them, Luna sees a large, swollen lips with a big, bloated cilt. She gives Celestia’s underbelly a nice slap, eliciting a moan from her blimp and some white liquid to drip from her marehood, before making her way towards the front.

Celestia sees Luna’s mischievous grin and huffs a bit in annoyance and the pressure in her body. Luna’s horn glows and Celestia’s body is surrounded with magic. Celestia’s body turns slowly forward to where she and Luna can see face-to-face. Luna giggles at the adorable sight of Celestia’s head with cheeks about as large as basketballs. “Celestia, you look so puffy like...like....” Luna stops herself to inhale some air before closing her mouth and leaving her cheeks a bit swollen, but smaller than Celestia’s. Celestia growls a bit but shivers from feeling pressure building up around the center of her belly. “Oh don’t give me that look, Celestia. You know you like this as much as I do,” Luna comments. She is right; Celestia does somewhat enjoy the feeling of being so puffed up, but this was forced onto her. Celestia glares at Luna again to show a sign of annoyance just before Luna lets out a sigh. “Looks like I may have to raise the pressure once again,...” Luna mutters before the two alicorns hear a loud popping noise come out from behind Celestia.

Celestia shivers and lets out a low moan after that as Luna grows curious. “Okay, what was that sound, Celestia? You had better not have a hole!” Luna shouts as she turns Celestia backwards this time. Celestia wiggles her swollen hooves as she turns but soon stops once she hears Luna gasps. Luna is looking at what appears to a pumpkin-sized dome on Celestia’s belly. She presses it with one of her hooves and hears a squeak come out of it along with another one of Celestia’s moans. “Sister...who knew your...belly button...could be so poofy as well!” Luna shouts and gives Celestia’s outie a teasing slap, causing it to wobble a bit. “Oooooh...s-so much...pressure,…” Celestia mutters out as her eyes become half-glazed. Luna rubs Celestia’s swollen navel for a moment until a rather naughty idea comes into her mind.

“Shall we step things up a bit, Sister?” Luna asks right before her magic turns the valve to maximum. Celestia feels her blimp body billow out greatly as she howls loudly. “And now it’s time for my own fun,...” Luna mutters as she turns out and spreads her legs just before pressing her needy, wet vagina against Celestia’s navel.

Luna begins to move her rump up and down against that swelling outie, making her quiver a bit. “Oooooh...L-Luna...what are you...doing?” the massive white blimp asks, feeling the fat moon princess grinding on her.

“Ooooh...this is such a good idea! You have no idea just how big you are right now arouses me, Sister!” Luna moans and continues to rub her fat pussy on Celestia’s belly button. Celestia begins to sweat from her red while her nearly watermelon-sized cheeks swell a bit and smoosh her muzzle. Her inflating pussy, which is big enough to take in two ponies, starts to shake and leak some cum. Luna lets out her tongue and begins to pant heavily and sweat from her sexual activity.

Celestia tries her best to remain calm but the fun Luna is having is simply so much...and she wants more. Soon, Celestia’s body starts to feel rather hot inside as if there is a fire inside her. Celestia’s eyes widen in realization. The heat from her arousal is cooking the air inside her body, causing it to increase and expand her even further. Another hissing sound appears, but it is much louder than the one from the tank. Luna feels her sister’s belly button swell and press on her rump hard, only helping to make her more aroused and grind harder. Celestia’s body is inflating twice as fast due to the combo of the air tank and the heat cooking up that air. Her butt cheeks can nearly be their own beds, with her tail looking like a tiny flag in comparison to one of those cheeks.  “Ooooh...I am so close, Sister!” Luna shouts as her pussy starts squirting out white liquid onto Celestia’s belly button. Her belly greatly dwarfs over Luna since it looks like it can hold a large dragon inside. Luna soon begins to feel Celestia’s belly button no longer pressing on her rear and plump pussy. Luna becomes confused and looks back to see that Celestia is starting to float away.

“L-Luna...I-I’m t-too...l-light,” Celestia moans out while attempting to flap her inflated wings once more. Luna immediately uses her magic to bring Celestia back towards her so she can finish herself first. Once the belly button gets close enough, she quickly grinds on it at a fast pace.

“Just a bit...m-more,...” Luna mutters out as her pussy quivers again and leaks more cum onto her stained belly button. Soon, she reaches her point. Luna howls loudly before her pussy begins to spray her white load all over Celestia’s navel and belly. She sweats and pants just before plopping onto the ground and losing her magical grip on Celestia. Celestia floats back up but stops thanks to the weight of the tank.

Luna presses her forelegs onto the earth and pushes herself up. “Mmmm...one of the best fun times I ever had,” she comments before turning her attention back towards Celestia. Her jaw drops upon seeing Celestia’s new size. Just her belly alone is almost as big as her castle now. Her hooves are almost completely sunken into her thick, tree trunk-like limbs. Her cheeks are bigger than her head now along with a bloated chin under her. Her wings have swollen so large that each feather could contain two ponies. Her ass cheeks can easily rival against the size of an Ursa Minor. Her wet, plump pussy has blown up quite a bit to the point where a tree can possibly be pushed into it. Her navel now matches the same size as Luna. Luna continues to watch in awe until she hears some creaks come out of Celestia when she moves.

“Luna...I am so...f-full,...” Celestia mutters out as the cool night breeze brushes against her tight body. “Luna...This feels so...good...p-please...p-pop me...I am so close,...” her blimpy sister states before letting out a moan. Luna moves over to the empty tank and disconnects the hose. She holds up a tight grip on it and her body weight helps keep her on the ground. She looks back up to Celestia’s lovely rear as her bloated sister bobs in the air.

“Here goes,...” Luna whispers as she takes a deep breath and blows into the hose. Celestia feels Luna’s breath go into her body and inflate her a tiny bit, causing the creaks to become much louder. She is close to just simply detonating like the blimp bomb she is. Luna inhales deeply enough to make her fat belly expand out a bit before exhaling it all into the hose again. Celestia’s body begins to slowly shake and emit ominous creaks while some air begins to leak out of her nostrils in an attempt to reduce the pressure. Luna takes a deep breath but holds upon seeing a bulge come through the hose. A loud fart sound comes out of it as Celestia’s head throbs like a pressurised cork. “Oooooo...getting gassy with me, Celestia? Let’s how gassy you will be after this!” Luna shouts and takes in a great amount of air that causes her belly to fill up and lift the fat princess up. She stuffs the hose in her mouth and blows all the air she had mustered. The blow hits Celestia’s anus first and pushes her body outwards enough to knock her over the edge.

Celestia’s over-pressurized body shakes violently as air spews out from her ears, nostrils, and tailhole. There is a long screeching creak that comes out of her body as Luna attempts to cover herself. Celestia lets out one last moan before her glorious, blimp body makes a deafening explosion. Tornado-speed winds toss grasses, bushes and trees away while shattering some of the castle windows. Luna tries to hold her ground as the eruption pushes her back quite a bit. The winds soon die down as white pieces rain down from the night sky. Luna soons sees a bigger object fall from the sky. It hits the ground with a plop, and she moves over to inspect. Celestia is laying on the ground naked with a dazed expression. She utters out a groan and shakes her head. “Sister! You’re back to normal!” Luna shouts excitedly as Celestia picks herself up.

“Ugh...that was...oddly fascinating and fun, Luna,” Celestia replies as she rubs her own head. “Have you seen my crown?” Celestia’s crown falls back onto her head as the two giggle. “So I guess it’s time for bed, isn’t it, Sister?” Luna asks, sounding a little sad. “I’m afraid so, Luna,” Celestia replies before looking at Luna and then staring at the ground. “But….” Celestia turns around and presses her rump against Luna’s face, “I suppose I could go for short round of expanding.”