It was another lovely Canterlot morning.

After raising the sun, Celestia settled in for a hearty breakfast, relishing in every bite, not merely because of its taste as much as the knowledge that she had made it herself. She knew that, although popular approval ratings had never dipped below ninety percent in more than a century, there were those ponies who sneered at the royalty of Equestria for leading such pampered lives in their gilded palaces, and so she endeavored to do as much as she could without burdening others. The resources she used were all sourced directly from her personal stock, grown in her gardens, going so far as grinding her own flour. She even had a private supply of milk. There were plenty of recipes she could try, with new ones sneaking in every other month or so, but she found that could never go wrong with pancakes drizzled with syrup and an assortment of fruit on the side.

So she had her meal served, and she had a serene smile on her face while she ate and skimmed over the newest document that had been sent to her desk (today it was a proposal for new development in the Badlands; she would have to cross-reference the treaties for buffalo territory before coming to a decision).

And then Luna entered the room.

Both alicorns were tired in some way in the morning, but in different senses. In Celestia’s case it was the grogginess that came from a full night’s sleep, largely shaken off by the time she had finished cooking. Luna, on the other hand, was at the end of her nocturnal working shift, and thus was showing telltale signs of exhaustion. Today she was carrying herself with some degree of poise, but the sisters knew each other well enough that the signs were easily discerned: a distinctly listless expression, wings hanging slightly askew instead of folded against her back, and the stars in her mane faded. She wordlessly sat down in the seat across from Celestia, where there was another plate of pancakes for her—dinner in her case, technically speaking.

The elder sister said, “Good morn—”

There was a commotion, shifting and clattering. Luna’s placid expression turned to one of frustration as she glanced down at herself. She had her hands on the arms of her chair, gripping tightly (there were grooves forming in the old wood from how many times her fingers had dug into it), grunting while she wriggled her hips. The chair creaked ominously when she bounced upward and awkwardly pulled its feet inward so she could be in the proper position at the table. Once she was in place, she grumbled, brushing at her starry mane, and turned her attention to the pancakes in front of her.

“…Good morning, Luna,” Celestia spoke again, with no small amount of unease, the pleasure of her meal having been forgotten. “I apologize sincerely if you had an unpleasant night. Is there anything you wish to—”

“Why are all the chairs in the palace so small?” Luna interjected in the middle of wolfing down chunks of syrupy dough.

Celestia stared and blinked for several seconds before she responded, “What?”

“The chairs, Sister,” Luna repeated, and she rapped her knuckles on one of the arms of her seat, “the things we park our posteriors in.”

“I know what a chair is, Luna.”

“Do you?” She snorted. “I am not certain that you do. I would wager that there is not a single adequate chair in this whole palace! The whole night I had to go from one conference to the next, and no matter where I went it was the same thing: miniscule seats that make me feel like I am squeezing myself into a thimble!”

Still Celestia stared, but this time her eyes narrowed. Suddenly she understood what this was really about. “Well, Lulu,” she asserted, “perhaps you wouldn’t be facing these struggles if you weren’t so gung-ho about the pancakes.”

“Do not even start with me on that, Tia,” Luna snarled back, jabbing her fork toward her, “need I remind you that you have been eating like royalty for a millennium while I was stranded on the moon. With how much cake you scarf down on a daily basis—”

“I have been cutting back on the sweets, thank you.”

“—I am quite frankly astonished that your tits are not filling the entirety of the reception hall.”

With a scoff, Celestia crossed her arms over her substantial chest, the mass cushy and soft through the silky fabric of the robe she wore. “My breasts are my business, Lulu, just as your fat bottom is yours.”

“You say that as if they are not a vital part of your cooking. I wonder if that is part of the reason that we are even having this problem.” Luna practically inhaled the rest of her breakfast before standing. The chair came with her, wedged into place, and she had to shove on it to extricate herself from its clinging embrace. She turned and left the dining room without another word, and Celestia saw that the ethereal miasma of her tail wasn’t nearly enough to obscure the bulk of her rear, hips and thighs broader than her shoulders, the shape of her buttocks outlined by the draping skirt of her dress.

The elder alicorn sighed and slumped back in her not-nearly-so-undersized chair. She looked downward, and her view was quickly taken up by her chest, the mounds filling her robe to its limits. The hem was parted slightly to reveal a valley of cleavage between the alabaster globes. She had grown so used to them, there were days when she didn’t think about how endowed she was—how she couldn’t fit her breasts in her hands, how she couldn’t see her stomach or hooves, how she continued to lactate despite not having been pregnant in decades. She felt no need to be ashamed of herself (though she did on occasion wonder what affect her buxomness had on that ninety percent approval rating).

It had always been like this, even since before the banishment. Just as sun and moon were opposites of each other, the two sisters had been physical opposites, their metabolisms working in clear opposing trajectories. Celestia had found herself blessed with a bosom that any mare would be envious of, while Luna instead developed a voluminous rear that hypnotized stallions (and mares) with its swaying. It was undeniable that the two of them were among the most beautiful ponies in all of Equestria, but it was rare that either of them would act especially nasty toward the other about their appearance.

Well, Luna had, as Nightmare Moon, vowed to bury Celestia underneath her ass, but that was a different time.

“Mmm…I should see about getting some new seats for the palace,” she mused to herself, “it can’t be a terribly unreasonable thing to do for Luna.”

And yet, there was a nagging voice at the fringe of her consciousness reminding her that it was a fruitless endeavor, for surely it would only be a matter of time before these new furnishings too were outgrown.

Celestia did her best to ignore those thoughts while she finished her breakfast, bosom rising into the lower periphery of her field of view as she looked down at the plate. Enough time had been wasted, she needed to get on with her business for the day. Though she didn’t leave without refilling another bottle with milk for tomorrow. It felt good to relieve the pressure behind her nipples.

= = = = =

Celestia did not see Luna for the rest of the day. Unsurprising, given that she would have in all likelihood retired to her quarters for the final hours before she went to sleep, but still there was some lament to be had. The more time went by, the more Celestia regretted how tersely she had behaved during their meeting and wished she could apologize. It wasn’t her fault that Luna’s butt was so big, and really it wasn’t her own fault either, it just happened to be the way that her body functioned.

In anticipation of her sister’s reawakening, she had endeavored to do as much as she could to show how much she intended to make it up for her. A lavish dinner of Luna’s favorite meals had been prepared, Marediterranean salad and seafood platters, the finest wine from the palace vaults, and pizza (she had grown quite fond of it in the time since her return). Celestia had fought with herself not to include any cake, purely as a show of good will. And, most importantly, there had been a prototype chair made on rush order, lacking the ornate decoration that would be expected of palace furnishing for the time being, but it was wide and sturdy enough to support a bottom-heavy alicorn.

So Celestia waited in the private dining room, determined not to begin eating before her sister arrived, even as the minutes ticked by like sweat running down her brow. She could be certain that Luna was awake, as the moon had been raised on time, but she was particularly late in arriving. Had she really taken what was said earlier to mind and decided to fast so she could slim down? Another pang of regret. Celestia truly didn’t want her to slim down, she figured that if the younger alicorn had stayed this way for so long then surely she must enjoy it.

“Maybe she got stuck in a doorway,” she muttered to herself. She promptly burst into a fit of giggles at her own humor, unable to help herself. The image of Luna trapped in the frame of a door because of the breadth of her own bottom was simply too funny.

And then Luna’s voice called out, pleasant and good-natured, “Good evening, Tia.”

Celestia looked up. She froze. She blinked. She was still seeing the same thing.

The blue alicorn’s hips were filling the doorway from one side to the other, more than twice the breadth she had been the last time she saw her. Each thigh was a massive slab of flesh thicker than her torso, tapering down gradually toward the knees and calves. The thick legs were fully on display too with the dark Neighjing dress that she wore, cut on either side so that their full length was visible.

“It is not like you to stare, Sister.” Luna’s mirthful teasing brought Celestia out of her thoughts and she looked up again. There was nothing so venomous about her visage this time. She was smiling contentedly. Meanwhile, Celestia became conscious that her jaw was hanging agape like a fish out of water.

Luna stepped through the doorway, only a brief moment in which she snagged against the edges. She strode forward with the kind of poise and elegance that was typical of her, even though the swinging arc of her hips was so much greater than before. Celestia didn’t want to stare, but it was quite difficult to do so. There was something bubbling up inside her and she wasn’t entirely certain what it was, but she didn’t think that she liked it.

When Luna came to the new chair that had been set out for her, she asked, “What is this?”

“O-oh, it’s…I was going to get new chairs made for you,” Celestia replied weakly.

“Oh, I see.” Luna chuckled softly. “Quite thoughtful of you, Sister, thank you. I believe that I have a simpler solution, though.” She then reached over (pushing out her protuberant ass in the process) and unceremoniously ripped off one arm of the chair. After that, she brought over the old chair that had been sitting there and did the same thing to that for the opposite side. She finally sat down on both chairs at once, one for each cheek. “Much better.”

The younger alicorn’s eyes roved over the spread on the table, lighting up with glimmers of excitement at what she saw, but then she seemed to have an epiphany and she turned her attention toward the mare on the other side of the table again. “So I assume you must be wondering what has transpired,” she said plainly.

“…Yes, you could say that,” Celestia replied, suddenly feeling dry in her throat.

“Well, what you said last morning really got me thinking.” Luna’s horn lit up and began piling heaps of pasta onto her plate while she spoke. “I must admit I was quite incensed for a while. I had more trouble going to sleep than I usually do. The audacity of the idea that I was at fault for merely desiring to live my life to its fullest…” She shook her head and grimaced, and there was a particularly forceful splat of red sauce across her plate. Celestia winced.

“But then…” she sighed as she continued, “I stopped and really thought about it all. Why was I ashamed of being the way I was? Did I not enjoy being so curvaceous?” There were creaking sounds from her chairs as she wriggled her hips and ground her buttocks into them. Her muzzle was forming into a smile once more. “No, this is exactly the way I always wanted to be. So why not simply…embrace it? Why not take it to its fullest potential? So I did just that. Thank the stars I still had a dress that could fit me, but I’ll need to see about some wardrobe adjustments in the future.” She chuckled as she began to eat.

“I…o-okay,” Celestia stuttered. Her hands were gripping tightly to the armrests of her own chair; she didn’t know when her nails had started digging into the wood. She found herself looking down at her chest, a chest which she knew was inordinately large compared to the commonponies of Equestria, and yet now suddenly seemed so very small. “B-but…how…how did you…manage to…”

“Come now, Tia, we are civilized adults,” Luna admonished, though still cheerfully, playfully, “just spit it out.”

After a few seconds of feeling as if her lips were glued together, Celestia managed to say, “How did you make your ass bigger?”

To which Luna responded, with a roll of her eyes, “Magic, quite obviously. Is it truly such a surprise? We are alicorns, Celestia, we are capable of nearly anything our hearts desire. You could figure it out in an hour or two, easily. We could find a way to make all of Canterlot super-sized if we worked together, I bet.” She gave a snort of laughter. “One step at a time, though.”

But Celestia was hardly listening at that point. She could barely even think about dinner, while Luna got to work devouring the meals that had been laid out for her. She didn’t know why she hadn’t considered the applications of body-altering magic before. Could it really be so simple? It sounded too good to be true, but she also couldn’t find any reason to think otherwise. She was an alicorn, one of the most powerful wielders of magic in the whole world, she ought to be capable of whatever she desired.

Dinner came and went. Celestia offered her apologies to Luna, which she accepted while also confessing her own regret for behaving so rashly. She tried not to stare at the mare’s rump swaying from side to side when she left. The Sun Princess retired to her own quarters for the night, but just as her sister had been she too found herself not tired in the slightest. She stripped from her clothes and gazed at her reflection in a full-length mirror in her boudoir. She cupped her hands just barely at the undersides of her breasts, pale mounds hanging to just over the ridge of her abdomen. There were many aspects of her visage that defined her: her billowing rainbow mane, her tall horn, her broad wings, the suns imprinted on her shapely hips. The breasts, though, at this particular moment they were what mattered the most.

But they were lacking.

That was simply unacceptable.

The mare’s horn lit up with a golden aura that filled the room like a miniature sun—distantly she heard Philomena squawking at her, having been woken up. A similar aura manifested around her chest, seeping into her bosom. She barely knew what she was doing, but she thought that it couldn’t be hard. She reached into herself, suffusing her flesh with her magic, though it took some concentration to do it in a way that wasn’t merely physical; the first attempt merely resulted in squeezing herself at random angles. Her heart filled with warmth and her pulse quickened, but it was joined by heat in her loins. She breathed heavily, clutching at her chest.

“Bigger…” she gasped, a sound that was barely more than a squeak, “bigger…!”

The weight in her palms amplified.

Celestia groaned while she staggered away from the mirror, but she hazily continued channeling her magic. She understood now: pouring mana reserves back into her body, converting it into mass. And, indeed, as an alicorn, there was a lot inside her, the floodgates held wide open. While she sprawled upon her bed, she kept her hands cupped over her pale-yellow nipples, the bare flesh expanding while also stiffening. Milk was gushing freely from within her, trickling over the slopes of her breasts like lava flowing down a volcano. She felt the fire in her loins begging for satisfaction, but she couldn’t tend to that, she was far too preoccupied with her nipples. The mattress squealed as she squirmed and rocked, gasping and crying with throes of passion. It was so terribly intense, blinding her with stimulation.

For the time being, she didn’t care about how big she was. She only cared that she was becoming bigger. She grasped her breasts tightly within her embrace, even as they fought to escape it, their girth outstripping the reach of her arms. She squeezed at her nipples until she felt the rush of climax upon her, and in the calm that followed, lying still and limp upon her bed, she felt their weight upon her, crushingly huge, reassuringly huge.

Yes, she was ready to embrace herself to the fullest.

= = = = =

“It does look quite nice on you, Sister…but…”

Celestia’s gaze immediately snapped to meet with her sibling’s. “But what?” she asked with an affronted edge scarcely concealed.

Luna pursed her lips. “Please, do not mistake me, I am quite glad for your decision to go through with this, Tia, I had hoped that you would join me in reveling in enormity. It is just that, well…now that it is upon us, I cannot help realizing that your position is just a tad…impractical.”

The elder alicorn quirked an eyebrow skeptically. “Impractical how?”

“Celestia.” Luna leveled an equally skeptical stare at her, crossing her arms over her front. “Your robe can’t even be closed anymore.”

It was true. The bathrobe which Celestia had worn comfortably the day before was now left far open in front of herself. There was no possible way it could have hoped to conceal the entirety of the beach ball-sized globes which extended from her chest, heavy teardrop mounds which had now obliterated any view of her torso save for the groin. It was a miracle that the lapels could just barely conceal her nipples, a sliver of bare yellow flesh visible amid the white coat, though the sash which she was using to wrap around her bosom and tie it in place didn’t look like it was going to hold for very long. The cool morning air was seeping in to waft at her skin as it rolled over the mountain slopes of Canterlot.

Celestia groaned. “Very well, so I am a tad indecent. Is it really such a troubling matter? I will have new dresses tailored by the end of the week, until then I will simply decree that it is a matter of royal importance that I perform my duties in private, so as to avoid causing undue panic among the masses.”

“Panic?” Luna smirked. “You think there will be outrage if we show ourselves as we are now?”

After a moment’s thought, Celestia grinned back. “Probably some, unavoidably, from those snobbish puritanical sorts. Maybe not so much, though. I imagine quite a few would be stirred into a very different kind of frenzy.”

“Oh yes, I am certain of that. I showed myself to a mare in a dream last night, and can you guess what she did?” She nudged the side of Celestia’s bosom, elbow sinking into the pliant flesh. “She asked if I could sit on her.”

The mare burst into a fit of giggles, and her sister soon followed. Beanbag breasts and buttocks wobbled gelatinously in the process. “Did you do it?” Celestia eventually managed to ask, wiping the tears from her cheeks.

Luna shook her head. “Alas, she woke up before I could commit to the deed. Must have been quite flustered.”

“I’ll bet.” But Celestia wasn’t thinking much about that nameless mare anymore. She was looking to the side at the broad swell of Luna’s hip, the black splotch and crescent moon stretched over its surface. It pushed outward more than half a meter, a broad shelf jutting toward her. How soft that cushy surface must be…

“Too bad,” Luna mused while leaning over the balcony banister, “I would have been quite glad to satisfy her. Perhaps another will appear to me soon. I am certain that most ponies in Equestria would be delighted to have some personal time with my rump.”

It was an innocuous statement. And yet it remained repeating itself over and over in Celestia’s brain long after Luna had left to retire to bed.

“Most ponies in Equestria?” she asked herself. The implications and questions wouldn’t leave her be. Never before had Celestia so dearly wished that she could have walked through dreams like her sister did and showed herself to ponies in the realm of sleep, where all things were possible.

The warmth of the rising sun seemed so distant all of a sudden.

But there was a different kind of warmth inside the alicorn, one which she summoned from the depths of her being.

She didn’t particularly give a damn who saw her as she pawed at her nipples through the strained fabric of her robe, steadily dampening as milk leaked through it.

= = = = =

Luna always woke with enough leeway that she could have some time devoted to personal efforts before she had to begin her duties for the night. She stood in front of a mirror that was far more crowded than it had once been, the glass surface scarcely containing the full breadth of her lower half. She placed her hands upon the crescent moon marks and squeezed inward, relishing the sensation of flesh compressing, just for a moment before she focused on the task at hand.

The shorts that she squeezed herself into had been rather comically small before, but now the elastic was stretched to its absolute limit, digging into her sensitive skin, riding high into the crack of her nethers. It was far from comfortable, and probably not conducive for her in the long run, but it made her loins tingle and it amused her, and what was more important than that? If anypony told her that it was inappropriate then she could tell them respectfully to shut their mouths and turn the other cheek. After putting on a matching sports bra and tank top and tying her starry mane into a ponytail, she was ready to make her way down to the palace gym—perhaps she could cajole Celestia into joining her sometime, give the guards a healthy helping of both the upper and lower halves.

Speaking of the guards, though, there were oddly few of them out and about. After descending the stairs from her observatory, she found nopony standing outside the entrance as there should have been. Luna’s chest promptly filled with a righteous fury; it may have been true that Equestria was presently at peace, but that was no excuse for negligence, and she would see that the guards in question were duly reprimanded. But that proved to only be a prelude for what was to come, as she discovered that the halls of the palace were deserted, not a soul to be seen as she made her way. She would normally take a leisurely jog on a circuitous path, taking stock of the palace in the process, jiggling and bouncing all the while, but on this day she was led to the discovery that seemingly everypony had abandoned their posts.

Just as she was beginning to ponder if she should raise an alarm, she spotted a pony scampering off down a corner ahead of her. “You there!” she called out, her voice booming in the vaulted halls, “Where is everypony?!”

But, to her astonishment, they didn’t even turn her way, only kept going, disappearing around the corner.

Luna was aghast, a tad hurt, and more than a tad annoyed at the idea that somepony could deign to ignore the gyrations of her hips. This would merit far more severe punishment.

She came to the corridor, and she was met with the answer to her dilemma: thronging crowds of palace guards and servants spread throughout the hall. The alicorn was puzzled, but then after a few moments it occurred to her just where in the palace she was, and what room lay just ahead. Her brow furrowed and she muttered under her breath, “Just what has she been up to while I slept?”

There was not a care in the world to be had as Luna strode ahead. She made little effort to weave around the crowds of ponies, instead plowing through them. Being nearly a head taller than the average adult pony, she had no difficulty seeing over them, but her rump was effective for bumping anypony foolish enough to stand still out of her way, swinging this way and that like a battering ram. There were gasps of alarm, but she dimly heard far more exclamations of shock and amazement.

“Wait, that’s Luna?”

“When did she…?”

“Holy shit, that ass…”

She scarcely paid that any mind. She was focused on the door that was flanked by two guards in golden armor, Celestia’s retinue. As she approached, they stood to attention, prepared to rebuke her, only to then promptly falter, both of their gazes listing downward. “P-Princess Luna…?” one stammered.

“Stand aside,” she ordered, a powerful force behind her voice even though she didn’t truly yell. She was already reaching to step past them before they reacted.

“N-no, wait, you can’t—!”

“I may see my sister whenever I please!”

And then she threw the doors to Celestia’s office open.

The mare with the rainbow mane turned to face her immediately. The ponies who were preoccupied with massaging her breasts did not do so. The pale globes seemed larger than any of them, nearly eclipsing their own owner, reaching to hang just at her knees. Milk gushed from the nipples at their far ends, pouring into two vats on the floor; there were more that were already full, others waiting to be filled.

“Oh…Luna…!” Celestia had a sheepish smile on her face. “You’re awake! I…wasn’t expecting to see you until dinner…I was just…trying to shore up the castle’s milk supply for the next month!”

The blue alicorn was hardly listening to her, though. She had her attention upon the ponies who were attending to her sister’s breasts—two for each, one on each side, three stallions and one mare. They were in varying states of undress, and they seemed to be quite engrossed in kneading and groping and pressing up against the pliant flesh. At least, that is, until Luna passed over them, staring at each of them one by one in the way that a disappointed teacher might reproach a misbehaving student. One particularly ashamed-looking stallion she recognized, and he hadn’t helped his case by still wearing the blue helmet that had been part of his uniform.

“So, Sister,” Luna barked gruffly, “you were quite enamored with the idea of having bigger breasts, hmm?”

“L-Luna, I…” Celestia now looked most ashamed of all, but there was still a heavy blush on her face. Her hands were firmly pressed to the sides of her bosom, squeezing the doughy mass, applying pressure in a steady gentle rhythm. “I…I just loved how it felt, getting…bigger. You…you understand how it feels, yes?”

“I do understand,” Luna replied sternly. “I understand that you thought it prudent to steal all the ponies of the castle for yourself! Again!”

That made the mare really balk. “What?! N-no, it’s…it’s not like that at all, Luna! It’s not like…l-last time!”

“Is it not, Celestia?!” The ponies who had been tending to Celestia now huddled against her as Luna seethed, a terrible aura manifesting around her. Even her enormous bottom and thighs could not detract from the intensity of the arcane power which enveloped her. “I thought you would have learned! I thought you finally understood! Now I see I was mistaken all this time! There’s only one thing I can do!”

And then she placed her hands on her hips. All at once, the magic flowed back into her, and in an explosive surge her bulk doubled upon itself. The elastic shorts she had been wearing gave up instantly, snapping apart, and the release of that tension added an additional fit of bouncing to her girth. The alicorn’s hips and buttocks now formed a shelf all around herself, flaring dramatically outward from a waist that was still trim and fit. Forget chairs; she would have to start looking into couches to sit upon with that kind of width.

Celestia could only stare, dumbstruck. The ponies around her were terrified, but nonetheless aroused. Quite a few more were crowding around the open doorway, staring at one alicorn or the other, or alternatingly both.

Taking note of her audience, Luna looked back over her shoulder, and she bore a savage grin as she asked, “What do you all think?” She shook her ponderous hips from side to side, buttocks wobbling, and then she punctuated it with a sharp slap to one cheek. “Ravishing, would you not agree? Does my rear not fill you with temptation?”

Celestia interjected, “L-Luna, you can’t—!”

“Yes!” somepony shouted in the background, which was then met with a small chorus of similar assertions.

“Now see here!” Now Celestia forced herself forward. The slightest movement caused her bosom to shake tremulously, swinging in pendulous arcs. The ponies who had been caught up in her flesh tripped and stumbled. “You can’t just rile up our subjects into a frenzy like this!”

“And is that not exactly what you have done, Sister?!” Luna hissed back at her accusingly, returning with an angry glare.

“Of course not!”

“It certainly looks like that to me!”

“Well maybe you should try getting your head out of that fat ass of yours so you can think clearly!”

“Maybe you should plug up your leaking tits before you flood the whole castle!”

Horns flared. Their magic was not focused outward but inward. They were on a hair trigger. The ponies watching were torn between ducking for cover and rubbing one out.

Celestia faltered. “N-no, wait.”

But Luna sneered at her, planting her hands on her hips.

“STOP!”

A burst of force rippled through the air like a supersonic wave. Papers and folders flew up chaotically and bins fell over, along with several of the onlookers. Luna flinched and staggered but remained standing. Celestia huffed, panting, slumping forward, her immense bosom that much closer to making contact with the floor. “This…this is pointless,” she muttered, and when she faced her sibling her eyes sparkled with sincerity, “we can’t go on like this, Lulu.”

Luna remained on guard for several seconds, poised for retaliation, but gradually she allowed herself to ease her posture, wings folding against her back, horn dimming. She still stayed silent, staring expectantly.

“I’m…I’m sorry, Sister,” the elder alicorn admitted, “I just couldn’t help myself…I wanted…more.”

Eventually, Luna heaved a slow sigh, and she smirked. “It does feel quite good, does it not?”

“Y-yes.” Celestia gave an awkward smile while staring down at the vast canyon of cleavage that extended from her front. She chuckled nervously. “It’s…quite stimulating.”

“That is very apt.” Luna placed her hands on her thighs and slowly traced around the circumference of her breadth, as far as she could reach (which wasn’t very far). “But we cannot allow this to get the better of us. We must not let it come between us.”

Celestia nodded, and, just faintly, there were tears in her eyes. “I would never let that happen, Sister.”

“Nor would I.”

“Your…your butt is quite nice.”

“As is your bosom, Sister.”

They moved to embrace each other. That is, until coming to the mutual discovery that there was a sea of breast between them. They tried turning to the side, but now there was a vast swathe of buttock and thigh getting in the way. They finally had to come in at an angle, Luna leaning into the side of one breast while Celestia ground against the front of one thick leg. But, all the same, embrace they did, nuzzling gently into each other’s warmth, smiling.

A guard sniffled and wiped at his eyes. “So beautiful…! I love happy endings!”

The serving mare beside him scoffed. “As if. Did you see how horny those two were, and how hard everypony was simping for them? There’s no way this is gonna last.”

= = = = =

And, indeed, it did not last.

“Dearest…Sister…” Luna muttered to herself while she scribbled the words on the slip of paper. The words didn’t quite resemble what she was saying, though, let alone her usual neat cursive handwriting. It might have had something to do with the fact that she was standing hunched over her desk instead of sitting; it wasn’t like her chair could accommodate her at this point. It probably had more to do, though, with the occasional spasms that rocked through her, prompting her to gasp as she wriggled her hips.

“I apologize profusely for…reneging on our…agreement.” She bit her lip, swallowing a moan. “I truly did not…wish to do anything that would…sour the relationship between us or…our ponies…I simply…could not resist…”

But then she gasped as her whole body shook and the quill slipped from her fingers. Her knees nearly buckled and she grasped at the edge of the desk for support. Had there been anypony in the bed chambers with her, they would have been treated to a fantastic view of her rear sticking out behind her, moons that lived up to her title quite well. “Just…just a little more,” she gasped, a giddy smile across her muzzle and a blush on her cheeks.

The alicorn stood and tenderly placed her hands upon her hips, kneading into the silky fur and pliant surface. The touch was so delightfully tantalizing. And that was before her horn sparked and sent magic coursing through her fingers and into her rump. Her wings fluttered and twitched as she traced along her enormous breadth, around the thighs and back up over the cheeks. As she did so, the surface pushed back against her ever so subtly, swelling and pulsing. Another few centimeters’ worth of padding. Just to be safe.

But she wasn’t done after that. She felt so good, so energized. Her palms continued to rove across the surfaces of her hips and buttocks while she shimmied and shook in a swaying, undulating dance. One might have been forgiven for thinking that she was a performer at a gentlecolts’ club in Canterlot rather than a princess. She didn’t have an audience, but she did have plenty of mirrors. There was yet to be a single mirror in the palace that could adequately contain her reflection, so she had made do by having multiple angles, spread out all around her, so she could glance this way and that at herself to see the way her tree trunk legs shook with every step. She cried in delightful ecstasy, juices drooling between her thighs.

When Luna had had enough, panting and gasping, she turned back to her letter, only to discover that she couldn’t for the life of her recall the train of thought she had been on. She stared at the paper for several long seconds, pondering, but in the end all she could do was sigh lamentably. “No, I cannot cower behind a mere letter,” she grumbled as she steeled herself, “I must speak to her directly.” She felt some shame at herself, in the way she could no longer see the far sides of her hips and thighs, in the way she trembled and quaked, in the way her hooves stomped with every step, in the way she was at all times conscious of her size. And yet at the same time all that served to please her, to encourage her, to arouse her, and that explosive cocktail was far more important. “We ought not to fight each other over these trifling matters,” she muttered whilst glancing around at her reflections one after another, “we ought to enjoy ourselves.”

So she left her room to seek out her sister.

Well, it was easy enough to say that, but the actual process was far more involved than that. The expansive spaces of the royal palace no longer seemed quite as capacious as they had once been, as Luna could scarcely walk anywhere without bumping into something. Furnishings toppled over left and right as she swung about, still not accustomed to the additional girth that she was carrying. There came the sound of Tiberius squealing from somewhere when the shadow of the moons passed over him, threatening a total eclipse. And doors were an almost fruitless endeavor; she had to turn to the side and shimmy her way through, and even then her rump was still grinding against the edge several feet behind her while her chest and stomach were squeezing into the side in front of her.

And then she came to the corridor, and her devoted were waiting for her.

“Princess!” a chorus of voices called as all at once they came to her. There were a couple dozen ponies eagerly looking at her—three more than there had been before the last time she retired to her room. Most of them were from the Night Guard, but a few of them were other palace servants. They showed their support for her by not wearing anything over their lower halves: no pants, no skirts, and certainly no underwear. The stallions were quick to show their approval for her decision to plump herself up again. Hands were reaching for her, feeling her soft mass, prying at the patches which had stretched beyond her reach. She allowed herself to revel in this exultation for just a minute. Or two. Or five. She lost track.

“Thank you, thank you all,” Luna replied to them, easing them down, “please, though, I must not dilly-dally. Is anypony aware of Celestia’s location?”

That got them to shut up right away, shooting each other anxious and wary looks. Eventually one mousy stallion said, “I think I last heard she was in the dining hall.” His expression hardened somewhat as he then asked, “What do you care about seeing her for?”

“‘Tis nothing, my little ponies,” Luna replied with a smile, and while she passed through the crowd she brushed against that stallion with her hip, a hip that completely smothered him. It was intended to be a gentle motion, but either due to underestimating her strength or the stallion suddenly going weak at the knees in the process he suddenly slumped over, listing out of consciousness. “I simply wish to speak with her.”

Luna made her way down the passages of the palace, a single pony taking up nearly the entirety of a path which once could have accommodated several ponies standing shoulder-to-shoulder. She passed by a number of other ponies who were going about their business, and they offered her varying reactions. There were those who still reeled in disbelief at the state of affairs that had overtaken the palace. There were those who had the fortitude to go about business as if nothing had happened. There were those who were more sympathetic to her cause even if they had not fully aligned with her, a tad more enthusiastic in acknowledging her. There were those on the opposite end of the spectrum who regarded her with unease.

And there was one mare who wasn’t wearing a top, letting her breasts hang freely. They saw each other, and she promptly flinched, nearly jumping out of her hooves, fur bristling. Luna looked at her impassively even as she trembled, staring back with a mixture of terror and resentment. “Good day,” she said in the stern authority that had once been her norm, not the saccharine warmth that she had allowed for her devoted, “I am searching for Celestia, do you know where she—”

The mare turned and ran without a word.

Luna heaved a long sigh. “Very well.”

The alicorn managed a more concerted movement, jogging down the hall after the topless mare. It wasn’t too difficult, and it only had the effect of causing priceless vases and statues to go toppling over in her wake while the floor was marred with webbed networks of cracks. Her buttocks bounced upward behind her with each pumping step, rising as high as her head at the apex of their arc.

And, indeed, she found herself at the dining hall. She could tell Celestia was here because her retinue was spilling out from the room. There were considerably more of them than there had been among the crowd waiting at Luna’s bedroom. She took a deep breath and swallowed the urge to be bitter about that. It wasn’t going to matter anymore soon; she and Celestia would settle their differences and put this behind them.

She cordially requested passage through—many of these ponies actively gave her a wide berth, backing away from her as she approached—and made her way inside. Celestia was there, at the long table; she had to sit at an angle so she could reach her plate where there was another cake in the process of being devoured. There was a brief moment of the two of them staring at each other in which Luna thought that she saw a perfect reflection of her own face in Celestia’s expression: blank, stunned into shock. A host of yet more ponies were surrounding her, bearing amenities should they be requested, or massaging her sprawling bosom.

Her bosom which was now unquestionably larger than it had been the last time they saw each other, gargantuan mounds which each looked wider across than a pony was tall.

The train of thought that had been running strong in Luna’s mind was derailed quite promptly.

“What have you done?!” she shouted.

“What have I done?!” Celestia repeated in disbelief, “What of yourself, Sister?! What have you even done to yourself, have you looked in a mirror lately?!” She extended one hand and swept it out broadly, gesturing to the whole of the younger alicorn, and she sneered and scoffed. “Did you honestly believe that have a couple boulders grafted to your rear would be appealing?”

“Yes, in fact, I did, thank you very much!” Luna scowled back, and she planted her hands on her sloping sides while gyrating her hips. “And I’ll take my boulders any day over a couple of leaking zeppelins!”

She left, not caring when her swaying motions sent some ponies flying in the process.

That was when matters really got out of hand.

Author's Note

The original prompt for this story was "Celestia and Luna debating hyper tits vs hyper ass." It probably would have been really easy to have them start out being big and get into shenanigans from there. But I am nothing if not prone to overcomplicating things. I mean ambitious. So I decided to do a series of short scenes showing how Celestia and Luna steadily go nuts about busts and butts. And then it got...kind of long, as the fact that this is a Part 1 should indicate.

If the line "She even had a private supply of milk." doesn't set off alarm bells in your skull then you clearly don't read enough fetish junk.

"What IS this? A chair for ants?!"

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