The sound of a single pair of bare feet stepping repeatedly against a cold, marble floor could be heard echoing quietly across the wide, intricately decorated halls of Canterlot Castle. Each step seemed to have the essence of weight to it, and their constant, rhythmic pace seemed almost unstoppable. The source of the sound was from none other than Princess Luna, the Princess of the Night and co-ruler of Equestria. Her figure was noticeably absent of a single ounce of clothing, as was customary when it came to the princesses-- a tradition started by none other than her proud sister Princess Celestia-- an alicorn whom took great pride in her bodily assets. Too much pride one could even argue. The only sources of attire on Princess Luna were regal decorations: A potent black crown that symbolized her rule over the nighttime, and a black necklace with a crescent moon displayed on the front, just like the crescent moon presented on her cutie mark. Neither of the royal ornaments did anything at all though to hide the two most noticeable and obvious things on display: Her large, fully-exposed breasts.

The weight behind her footsteps now made sense, as with each step that she took, her perky yet tremendous boobs gave a slight bounce from her chest. Relative to the rest of her body, they were huge, and they gave hypnotic vibes the way they bounced and swayed with her movements. Luna knew the essence they gave all too well-- her breasts were important. Her two over-sized sacks of warm, squishy fat gave off the impression that they were extravagantly being displayed, even though Luna herself was paying them no mind. She wasn't touching them or holding them up with her hands-- she was simply letting her huge tits stick out freely from her chest, exposed in all of their glory. This is what Luna preferred. In her mind, it was a testament to how amazing she thought her breasts were. She didn't need to support them, or to have her hands holding them up even further to show them off; her love came from showing them just how they were all by themselves, to simply let them hang from her chest and do whatever they wished.

Luna's train of thought was soon interrupted though, which caused her otherwise rhythmic steps to halter slightly. It was an all-too-familiar sensation that she felt down just above the area in-between her long, sturdy legs... the urge to pee. It struck with no concern for what else was on Luna's mind, and it did so by telling her that her bladder was filling and wished to be emptied soon. Princess Luna, however, frowned at this bodily reminder. She wasn't about to stray where she was going and head for the bathroom, especially when she was perfectly capable of holding it for much longer. What she felt she wouldn't even consider an urge-- it was more of a nuisance. All it did was remind her that she had a bladder, something that would have to be emptied in the future, but now was not that time. Her bladder's purpose was to hold in her in her urine until she saw it fit to empty it, and Luna was proud to exercise her ability to put off going to the bathroom.

Luna's second distraction then came in the form of her older sister Princess Celestia. She was walking towards her in the distance, and she was naked just like Luna was. As usual, Celestia's arms were crossed and tucked right underneath her equally as large breasts, holding them up and making them look bigger and more profound than they really were. Luna rolled her eyes slightly at this: Celestia was always showing them off like that. There was rarely an instance where Celestia was seen without her enormous breasts being flaunted in such a braggadocious way, where it was always obvious just how proud and smug she was towards them. Luna however was not so open, choosing to show off her large bust in the most subtle and modest way possible-- to let them simply speak for themselves. Luna slowed down to a stop when she saw her sister slow down first, indicating that she likely wanted to talk to her. Luna took a second to glance across Celestia's nude body, seeing her prominent, bright pink nipples pointing right at her before speaking up.

"How are you today, dear sister?" Luna asked, her voice calming but with insistence and authority.

"I'm doing just fine Luna, thanks for asking." Celestia replied with a small smile. Luna watched as Celestia's gaze lowered down across Luna's body, before stopping right at where her lower-abdomen was. She looked for a second longer, until her lips began curling into a smirk-- just from that expression alone Luna already knew what was coming. More teasing. "Are you sure that bladder of yours is okay by itself? I wouldn't put it off for too long, you know~"

Luna immediately rolled her eyes and frowned at her sister's teasing, sighing and outwardly showing her annoyance-- she was no doubt referring to her bladder bulge which must've been noticeable by now. As of recently Celestia had been teasing Luna for just about every minor little thing, which had increasingly been getting on her nerves as time went on. "I'm fine, Tia. I am no-where near that close to peeing and you know that." Luna rebutted sternly, looking back into Celestia's eyes as she tried to make it clear how ridiculous her claim was. "I'm not a foal."

Celestia giggled lightly, clearly enjoying herself as she began to gently shake her body back and forth, making her large, exposed breasts wobble with her in response to her movements. "Sure~ You can't even last a week without having to pee."

Luna raised an eyebrow at her sister's response. A whole week? Of course she couldn't last that long-- was she expected to be able to last that long? That was seven whole days! "Of course I cannot last a week, Tia. One week is simply too much for anyone." Luna replied in defense of her holding abilities.

"Too much for anyone?" Celestia further inquired, eying Luna's bladder and jiggling her own breasts in her enjoyment of the moment.

"Yes. The task of holding in one's urine throughout an entire week is simply too daunting. The need to pee is a natural necessity for all living creatures, and we are no exception."

Celestia simply smiled and stepped closer to her sister, close enough for her large breasts to be only inches away from touching Luna's just as ginormous pair. "Well, I didn't say forever Luna~ I only said a week. As living creatures, we also have the ability to contain our bladder's contents and then release where we see fit. Surely it would be possible to prolong the necessity to pee for such a finite amount of time."

Luna groaned lightly as she listened to her sister speak and then blinked, taking a second to realize how Celestia was somehow managing to tease her for something as ludicrous as being unable to hold in her pee for a whole week's time. She looked downwards at the marble floor, closing her mouth more firmly and shaking her head. Her older sister's teasing had definitely been getting out of hand lately, and it only seemed to be getting worse if left on its own; however, Luna didn't know what to do about it. She had already brought it up once before, but was shot down by Celestia saying that it was only light-hearted and that no hard feelings were intended. Despite that, Luna couldn't deny that it still bothered her. "So you expect me to contain my bladder for an entire week's time?" Luna asked, bringing her head back up to meet eyes with her sister.

"Well? Can you?" Celestia replied, rubbing her arms together and using them to make her large breasts lightly bounce up and down-- absentmindedly playing with her boobs was an unconscious habit for her by now.

Luna was about to respond to criticize the ridiculousness of what Celestia was getting at, but she stopped herself, instead taking a moment to think about what she was asking. Celestia's previous words remained in Luna's mind as she thought them over-- could she really hold in her pee for an entire week? She couldn't remember the last time she had ever tried to purposely hold in her pee for as long as she possibly could, or even the last time she had gotten extremely desperate for a bathroom for that matter. Luna knew from experience that her bladder was big and most often never got in the way of her princess duties. She could remember that the last time she had actually emptied it was yesterday morning, and it was only just now starting to bother her the evening of the following day, nearly thirty-six hours later. That left her with five and a half days remaining, which didn't sound all that long in her head... She had been around for a long long time and had overcome many challenges before-- surely something as basic as the need to pee wouldn't stop her. How hard could it really be?

With renewed confidence, Luna lifted her head back up, looking back at her sister with a smirk of her own. If there was anything that might put Celestia in her place to stop her teasing, Luna thought, this would be it. "A week? I shall try it. I last peed yesterday morning, so the task of another five and a half days shouldn't be too difficult."

Celestia's eyes widened for a moment with surprise at Luna's sudden shift in tone, but was quickly replaced with a look of curiosity. "Oh? You're going to try it Luna?"

Luna nodded and placed her hands on her hips, now brimming with confidence that was only amplified by the fact that her large breasts were sticking out so far from her chest and nearly always visible in her peripheral vision. "Yes I shall, Tia. If I am still containing my urine by the week's end, then you will have been proven wrong, as I would have held it in for an entire week."

Celestia blinked, an interested and excited smile growing on her face afterwards when she listened to her younger sister's words. "I can't wait to see this... And just what makes you think you can last for so long?"

"Well, it is only an urge to pee. We are capable of putting it off consciously until the time is right-- you said so yourself. I believe I am more than capable of controlling my own body."

Celestia smirked wider, glancing down at Luna's bulging bladder once more. "We'll see~" She spoke, eyeing the bulge for a few more seconds before bringing her head back up. "And you don't have to be so nervous too-- you can relax a little. It's just me Luna." Celestia continued.

Luna exhaled, only now realizing just how tense she was as she stood. Taking her hands off of her hips, she relaxed a little, re-positioning her feet on the floor and inadvertently causing her protruding breasts to jiggle slightly because of it. "My apologies. I am still a little unused to being here from the moon.."

"It's okay. It's nice to have you back." Celestia replied with a smile. Her sincere expression changed to a more playful one shortly afterwards however. "I gotta say though, I wasn't expecting such huge boobs to come back with you too. You should be proud of that~" She giggled, twisting her body forward and poking one of Luna's huge breasts with her bright pink nipple. "Mine are still bigger though."

Luna couldn't help but blush and smile a little as she listened to her sister, but the last bit stuck out to her in a way that bothered her. Celestia was always insisting that her breasts were the bigger ones, whereas to Luna, they just looked like they were the same size. "We do not know that for sure." Luna replied matter-of-factly. "The way you flaunt them so much and hold them up only makes them appear bigger."

"Says the princess who won't ever wear a bra, even if it was the last day on Equestria." Celestia responded with a grin.

Luna's eyes widened for a short time, and she flinched upon hearing the word bra mentioned. To Celestia, Luna's distress towards bras was nothing more than something silly; but to Luna, it went much deeper than that. Ever since she could remember, Luna had something referred to as totonsiphobia-- the fear of wearing bras. Just the look and thought of her boobs being contained by such a garment always made her incredibly uncomfortable, and she found herself subconsciously bringing her arms closer together for comfort.

"Ours are the same size, Sister, and I do not wear a bra because they are simply a waste in my eyes." Luna replied, going with the usual excuse that she would tell her sister.

"Sure, sure.." Celestia replied, stepping forward and poking Luna's shoulder with the bright pink nipple of one of her over-sized boobs as she begun to walk by. "Mine are obviously the bigger ones. Good luck with that bladder of yours though~" She smiled as she made her naked self down the hallway. Luna turned slightly to watch her leave, before continuing her way in the opposite direction, with her pace even more brisk than it was before.

"I cannot embarrass myself in-front of Tia like that." Luna spoke quietly to herself as she walked through the hall, bare feet pressing against the marble floor with each step. "I must, under no circumstances, allow my bladder to empty. Only Celestia knows how much worse the teasing will become if I let myself fail... I cannot let that happen. I took her up on this challenge, and now I must see it through to the end." Luna brought her hands up and pushed her large breasts to the sides so she could take a quick look down at her bladder. She could feel the weight of the impending task pressing down on her mind as she gazed at the slightly protruding organ, where she thought about how she was going to have to hold in her pee for the next several days... While it was mostly easy now, she feared the near future where it would no-doubt get increasingly difficult. That bladder of hers would only get fuller and fuller..... Shaking her head, Luna opted not to think about that inevitability for the moment. That time would come on its own, and there was no use thinking about it now.

Before long, Princess Luna found herself heading back towards her bedchambers, where she felt ready to head in and get some deep beauty sleep. Her pace wasn't as firm and sturdy as it was earlier, and her gait showed signs of exhaustion after her tiring day as a princess. Her tired gait reflected her tired mind: absolutely drained from a tough day of work. Her exhaustion did nothing to hinder the way her large tits protruded so proudly from her chest, however, softly bouncing and swaying from side to side with each step like always. At this point they weren't on Luna's mind though as she reached out and turned the handles of the double-doors that led to her bedroom, pushing them open and stepping inside. Her legs ached as they usually always did after so much walking, and she was eager to lay down on her bed so she could get off of them. If there was one benefit to that though, her thighs were firm and strong-- clearly used to so much moving around.

The interior of Luna's bedchambers gave off a dark, blue-tinted atmosphere as moonlight shined through from the pretty glass doors of her balcony. The carpet flooring was almost pitch black, if not for the various white, yellow and blue dots that represented the many stars of the night sky. Her bare feet pressed against the surprisingly soft and even squishy carpet as she closed the doors behind her, and she found herself curling and stretching her toes at the feeling; they were sore too, and it felt nice to not be on hard marble flooring anymore. The walls and ceiling were similarly decorated with deep blue colors and assorted stars, all of which made Luna feel right at home. Her bed was large with pitch black, luscious covers, and a chandelier hung from the ceiling above it, finely ornamented with all sorts of breast-like imagery-- no doubt a reference to her own huge, proud breasts. It wasn't her idea to have such a peculiar adornment, but rather, the idea came from someone who was currently jumping off the bed and in an excited hurry to see Luna.

"Princess Luna!!" The equine exclaimed, her four hooves pattering against the floor as she ran up to the tall, busty, bipedal princess standing before her. Luna's expression softened when she saw the vibrant pony run up to her, and she started to smile, squatting down and reaching her hand out to pet her.

"How are you, Purella?" Luna asked, stroking her hand through the pony's mane. Purella was a cute pony whom Luna had opted to keeping as a "pet", someone to keep her company and also flood her with love and affection. She was a bit reserved, but still got visibly enthusiastic when Luna was around, and she had a notable obsession towards the Night Princess's prominent bust-- Luna's favorite aspect of her. The mare closed her eyes as she happily rubbed her head against Luna's hand, and she then opened them a short time later, only to find her face right in-front of Luna's massive boobs. Her eyes went wide open in shock, and she softly responded as if she was talking to them, not taking her eyes off of them for a second.

"I-I.. I'm doing okay.. Princess Luna..." She gulped, and Luna couldn't help but smile as she looked down and watched the mare stare so intensively at her breasts. Luna couldn't deny that she absolutely adored this special type of attention to her two most proud bodily assets, and it was mostly why having such an acquaintance with this pony was so much fun. She enjoyed watching the pony gaze so longingly at her breasts, but then breathed in with a tense posture when she found herself suddenly forced to squeeze her external urethral sphincter rather hard. Sitting in a squatted position wasn't exactly easy on her bladder, and her legs shook slightly as she made sure not to let a single drop escape.

"That is good to hear, young one." Princess Luna replied, rubbing the mare's cheek with the palm of her hand before quickly standing back up to put some pressure off of her bladder. Her bare breasts wobbled and brushed against each other as she stood to her feet, and she looked down past them to see the mare gazing up at her.

"Are you okay Luna..?" She asked, most likely noticing the princess's tense and labored movements. Luna stood with her legs closer together as her bladder was the first thing to come to mind, and she eventually decided that there was no harm in sharing the challenge she had put herself up to.

"Yes, Purella, I am doing okay; however, I will tell you what I must do when I am finished with my bathroom duties."

The pony nodded her head lightly, her expression painted with curiosity as she stepped back to give the princess room. Luna smiled at her, and then made her way over to the bathroom, not bothering to close the door all the way as she walked up to the bathroom counter. The first thing she noticed was the mirror, which she took the time to look at as her completely naked self stood in view in-front of it. Like always, her boobs were immediately the first two things that she found herself looking at. She knew that her breasts were the two most obvious and most revered parts of her body, as shown by the way they protruded from her body so blatantly... It would be impossible not to notice them if anyone were to see her walking through the halls of Canterlot or anywhere else she happened to be. Her and her sister Celestia were seemingly the two breast-icons of Equestria, and both of them didn't mind at all that their busts were one of the most notable and prestigious things about them. Despite how much she enjoyed the outward attention, though, nothing would ever top her own personal and emotional reasons as to why she loved her breasts so much. Back when she was trapped on the moon, their importance was beyond what anyone could've ever imagined... and it was something only her and Purella knew about.

Luna placed her hands on her hips, having already gotten distracted by her own boobies as she gently shook her body from side to side. She watched as mentioned mammaries jiggled and swayed back and forth in response to the movements, bumping into each other occasionally in their free-spirited wobbling. Her eyebrows raised in an attractive manner as she observed her breasts' movements, to which she then stopped shaking her body, watching her breasts continue gently jiggling with leftover momentum until they eventually slowed down to a stop. The audible sound of heavy breathing proceeded to catch her attention, and she turned her head to see Purella watching her through the slightly open doorway. The mare's eyes went wide open when she saw that she had been caught, and she stood completely frozen still in place, holding her breath and not moving a muscle. Luna didn't seem to mind though, and only smiled sheepishly, knowing that the mare had been watching her weird self-obsessing.

"You can come inside, Purella." Luna spoke to the mare, turning her head back to the counter as she reached out and turned the faucet on. Luna heard the soft pattering of hooves against the tile flooring as she leaned forward, splashing and rubbing the cool refreshing water against her face. Once she finished and dried her face off with a towel, she looked down at the mare to see her looking up at her.

"Do you like looking at them..?" The pony asked quietly, to which Luna smiled, looking down at her bust.

"I do very much." She replied, making them lightly jiggle back and forth. "Although I suppose I should also admit that I am not yet used to gazing upon them in a mirror. Looking down at them as opposed to observing them through a straight-forward reflection is completely different. It is very alluring."

The mare blushed slightly and smiled as she listened to the princess's every word, ears perked up and all. She watched as Luna then grabbed her toothbrush, where she found herself staring at her Luna's breasts as if to watch and examine every little movement they did while Luna brushed her teeth. Purella eventually jumped up on the toilet seat for a better view, to which she stared at Luna's boobies both on her body and through the mirror throughout all of her activities, all while Luna idly tapped her feet and squirmed back and forth due to her bladder's occasional and non-worrying urges during her chores. By the time she was done by the bathroom counter, she stepped over to Purella, who was quick to hop off the toilet seat for the princess. Luna laughed at this though and leaned down to pet Purella's mane.

"I will not be using that facility tonight." Luna spoke, feeling a strange sense of pride in those words as she stood back straight. The mare just looked at her in confusion.

"You're not?" She inquired, looking up at her. "Why not Luna? I'm pretty sure you looked like you needed to go.."

"I will explain on the bed together." Luna replied, stepping out of the bathroom and walking towards her bed. The pony was quick to follow as Luna climbed onto her large, soft bed, with her breasts hanging downwards and swaying as she crawled over to the center. Once she was there, she pushed her tired legs under the black covers, which seemed to almost melt with softness as Luna relaxed and let her legs pressed right up against the blissful fabric. She then leaned forward to bring the covers up, but not all the way up, making sure to keep her breasts exposed as she tucked the white brim of the blanket against the undersides of her boobs. She exhaled in bliss to finally be relaxing on her warm bed, and she rubbed her legs against the amazingly soft covers as she turned her head to watch the pony making her way over to her. Luna smiled when she saw her looking at her protruding breasts, and she reached an arm out to pet her as she approached.

"They're so beautiful Luna.." Purella spoke softly, to which Luna nodded, bringing both of her arms over to the mare to pull her closer to her.

"Beautiful and strong." Luna replied, pulling the mare onto her lap right in-front of her breasts. Luna smiled as she watched her stare at them with wide eyes-- she was so close to them now-- and Luna lowered her hand to rub the mare's cheek. "To answer your question earlier, Purella... It is about Celestia. I took her up on a challenge to hold in my pee for an entire week in hopes of teaching her a valuable lesson."

Purella blinked, looking up into Luna's eyes in shock. "An entire week Princess Luna? Oh my gosh! That's such a long time..."

Luna nodded. "Yes. I need to hold in my pee for a whole week, which will be five more days starting tomorrow morning. However... I am feeling a little uncertain that I can do that. It has only been a day and a half, and my bladder is already quite bothersome. If I were to hold it for just another day and a half, it should be twice as full... which worries me. I would still need to contain it all for another four days, and when I think about it that way, I become very unsure of myself. I cannot see myself holding it for such a massive amount of time, but.. I cannot embarrass myself in-front of Tia. I have noticed that she is becoming rather self-absorbed lately and is focusing more and more on herself. I cannot allow that to get any worse, not to mention her constant teasing and belittling towards me. It would only feed her ego more if I wet myself, which I would not dare to do, but a challenge such as this just seems too far-fetched.."

Purella gazed into Luna's eyes, listening to every word of her concerns. Eventually, she lowered her head, where she gently prodded her hoof against Luna's belly. "I'm sure you can do it Princess Luna... Just think about how amazing you are. You're easily the most amazing person in all of Equestria! I mean... just look how big your boobs are too... Um.. they're so big..." The mare started to look down and stare at them, and Luna looked down at them as well. They were really really big... Luna wrapped her arms around them, seemingly hugging the huge beauties, when the pony spoke up again. "I'm sure if you try your absolute hardest you can do it.."

Luna blushed at the praise and smiled again, reaching one of her hands forward to pet the mare more. "I suppose you are right... I will just try my hardest. After all, it is just a normal biological urge." She paused for a second before continuing. "However, you have me intrigued, Purella. Does thou think my breasts will help me in my task?"

The pony looked down at Luna's prominent bust and quickly found herself staring as she replied. "Um... well yes.... of course they would Luna. They're like... the very definition of maturity and control, I think. They should give you an advantage compared to everyone else and I'm sure they'll give you the um.. confidence to help you hold it.."

Luna smiled and brought the pony closer, causing her eyes to go wide as she found herself quickly moving in-between Luna's breasts. "That is interesting. Perhaps you will be right." Luna watched as she brought the mare right in-between her large boobs, observing her reactions as she was brought close to two of the most special parts of Luna's body; she looked like she was almost panicking with anticipation, and Luna thought it was adorable.

"Th-they're so warm Princess Luna.." Purella spoke quietly, squirming back and forth as she got comfortable laying down on her belly. Luna watched with a warm smile and then petted the pony's mane, bringing her arms closer together to make her breasts press and squish against the pony even more. Luna's boobs were just as big as the pony's head, and the mare leaned forward, where she started to gently nuzzle her cheek against the ginormous sacks of love and fat. She looked up at Luna with her lowered head as her muzzle gently rubbed against one of the alicorn's dark blue nipples, and her hooves wrapped around Luna's sides as she snuggled in closely.

"They will keep you warm and safe throughout the night, Purella." Luna spoke, to which she watched as the pony began to rest her head right against one of her great breasts. Luna's boobs squished in slightly as they softly supported the mare's head with more than enough cushion, and she let herself relax vulnerably in-between them, freeing her mind of any worries or stresses as Luna's magnificent breasts gracefully encased the sleepy mare. Purella breathed out slowly as she relaxed, closing her eyes and feeling protected surrounded by Luna's bust. The princess smiled at this, enjoying the sight of the pony as she snuggled in so happily against her boobs. For the moment, things seemed like they would be okay-- maybe Luna would somehow manage an entire week. Luna's thoughts slowed as she began to lull to sleep as well, and she petted the snuggling pony softly, keeping her hand rested on the pony's mane until she fell asleep.

Author's Note

Based off the derpibooru reference picture, who's boobs do you think are bigger? Celestia's or Luna's? Or maybe they really are they same size.. It's been so long but yet I still can't tell. I'd love to hear what you think.

An un-revised version of this chapter can be found here: https://pastebin.com/AqVaeyZq | This was actually one of the first stories I wrote, and it was way back in 2013 (You can probably tell by the quality) The writing style and theme of the story is alot different, so if there's anything you like about it, please let me know