From a young age, Rarity knew she wanted to be a fashionista. She learned every textile trait, sewing skill, and tailoring trick. But for the longest time, she couldn't figure out why she didn't have her cutie mark. She took on making the costumes for her school's play, certain that achieving such a feat would make her cutie mark appear. But once complete, she was still blank-flanked.
Her teacher gave her praise for her work. Indeed the costumes were very nice. But her lack of a cutie mark made her feel otherwise. There must have been something lacking in her work.
"Nice!? They need to be spectacular! And the performance is tomorrow!" Rarity complained. So later that day, and the next, she went back to work on the costumes. She tried every trick she could think of but nothing seemed to work. The costumes just weren't right. And the play opened that night. Maybe she wasn't meant to be a fashionista after all.
But then, when it seemed that all hope was lost, her horn came alight, dragging her out of her home. She didn't know what was going on. She had no idea where her horn was taking her. But unicorn magic doesn't happen without a reason. She knew that it had something to do with her love of fashion. And maybe even her cutie mark! She knew that this was her destiny.
But after hours of being dragged along by her horn's magic, through that night and into the next day, her trip ended abruptly at... a rock.
"A Rock!? That's my destiny!?" She yelled in frustration. "What is your problem horn? I followed you all the way out here for a rock!? HHHMMFF! Dumb rock!"
Suddenly the sky exploded with a might boom and a myriad of colors washing across to the horizons. The force of the blast split the giant rock in two, yet strangely, left the tiny filly unscathed. The blast revealed that the huge rock was in fact a giant geode, filled with all manner of different colored sparkling gems. Her horn had the magic ability to find gems, she realized. These would be a fabulous addition to her costumes. But she was in the middle of nowhere, miles from home with naught but the fur on her back.
With a complete lack of any materials around her to make saddlebags, she had no choice but to pry them from their stone prison with her magic and levitate the entire lot at once as she made the long trek back to Ponyville. It was by sheer good fortune that her path didn't take her through diamond dog territory.
But luckily she made it back to Ponyville in time to augment the costumes for the play. Even though she left the day of the play's opening, and the trip out took overnight and into the next day.
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"But that doesn't explain how you got your curse." Sweetie Belle said, listening to Rarity tell her cutie mark tale for her sister's bed time story.
"Now now," Rarity chided. "I was just getting to that part."
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The part that Rarity had omitted when she told Sweetie Belle's friends happened on the trip back to Ponyville. Her path took her along the edge of the Everfree Forest. But it was daytime at that point. And most of the forest's more dangerous denizens would be sleeping deep within.
But as chance would have it, Rarity happened upon a rare wood nymph. A magical creature of the forest. Normally these creatures were impossible to find as they usually vanished when outsiders were near. But this one was caught in an old trapper's snare. The tiny fairy was in terror as Rarity approached, but relaxed a bit when the unicorn released it and backed away. Rarity had done the creature a favor. And a debt unpaid was a burdensome thing for those of the Fae.
"For your favor of releasing me, I will grant you a wish within my power." The nymph said.
"Oh, I wish I was the greatest fashionista in Equestria." Rarity said quickly. The nymph looked into Rarity's aura. The raw talent was there. It would not be difficult to tilt her fortune to that end. A slight nudge of her future, to meet some important ponies, to be noticed by the right crowds. The spell washed over her with a light 'snap'. And it was done.
"It shall be so." The nymph declared, before flying off, vanishing into the woods. Rarity trotted on, her gems in tow with absolute confidence now. But poor Rarity did not know a very important thing about the Fae. You never make deals with them. Even in your debt they are manipulative and tricksters, always seeking to meddle in the affairs of mortals and gain the upper hoof. The Fae are bound to their word, yes. Rarity would go on to become the greatest fashionista in Equestria. But her wish had gained her more than she had bargained for.
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"And so, on the night of every full moon, I am cursed." Rarity said, explaining her condition to her younger sister. "One night a month, I look absolutely horrid." She cried.
"No you don't." Sweetie Belle reassured her.
"No, it's true. I look hideous!" Rarity said. "That is why I have to hide myself away, and wear dresses so often."
"But it's not that bad." Sweetie argued.
"Oh, you can't possibly mean that."
"I do! You're still the most beautiful mare in Equestria."
"Do you really think so?" Rarity asked. Sweetie Belle nodded. "Oh you really are the best sister a pony could ask for." She said as she hugged her. Outside, the full moon rose above the horizon into the night sky. "Are you ready?" Rarity asked. Sweetie nodded again. "All right. Here we go..."
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From a young age, Sweetie Belle understood that her older sister was special. She was beautiful, and talented, and generous. She admired her, she longed for Rarity's attention and approval in all that she did. But there was always something else about her. Some shameful secret that held her back. Rarity couldn't keep it a secret for long with the curious filly living with her.
It happened on the night of a full moon. Rarity had sequestered herself away for the night as she did every month. She hated that she had to keep secrets from her sister. But Sweetie could never find out about her... condition. She struggled with her transformed body, trying to pick out a dress for the next day to conceal her deformity. Sweetie opened Rarity's bedroom door.
"Sis, I know you don't want to be bothered on your special night but I can't find-" Sweetie's words evaporated. She couldn't believe what she saw. Rarity screeched and covered herself with the bedding she tore from the mattress in haste before shooing Sweetie out of the door, slamming it shut, being sure to lock it this time. Sweetie had seen her, like this! She crawled under the covers and bawled into her pillow. She would never be able to look at her older sister the same way again.
Out in the hall, Sweetie's mind reeled. Her older sister, Rarity had... colt parts! For the next couple of days Rarity remained locked in her room, briefly emerging only to eat. And always heavily concealed in large ensembles. But when she caught Sweetie's eyes, it told her all she need to know.
She'd seen everything.
But after the third day, Rarity emerged unburdened with clothing. She was smiling an back to her chipper old self. As if nothing had ever happened. Sweetie Belle for her part hadn't forgotten however.
Now it was no secret that most ponies went about their day without clothing. And any casual observer could see the privates of a pony with minimal effort. It was just good courtesy to not. Sweetie Belle understood this unspoken rule perfectly well. But idle curiosity couldn't keep her eyes averted forever. The differences in the two genders' anatomy were taught early to remove any mystery to foal. After all, they'd say, it was a perfectly natural thing.
Since then, Sweetie Belle had never gone out of her way to look at her sister's privates. She knew full well that she was a mare. But today, she needed confirmation. It didn't take long. She hatched a plan to sneak up on Rarity while she was washing the dishes. The noise of scrubbing would mask her approach. It was working. She got closer, keeping close to the floor. From her low angle, she could easily see under Rarity's tail. Normal mare parts. No sign of what she had seen three days ago. She scurried back to the doorway and entered deliberately more loudly this time.
"Rarity, can I talk to you?"
"Of course you can, dear." She said, finishing in the sink.
"What happened three days ago? Why have you been hiding in your room?" Sweetie asked.
"Why, whatever do you mean? I've just been a bit ill. I didn't want you to catch my bug." Rarity feigned.
"You were a, you had stallion parts."
"Oh don't be silly. I'm a mare. You know that. You must have been seeing things."
"I know what I saw! You had- you had a penis. I saw it." Sweetie said. Rarity sighed and dried her hooves, sitting at the table. She motioned for Sweetie to sit opposite her as well.
"Sweetie, I know what you must think you saw. But I really am a mare. I don't want you or anypony else thinking otherwise."
"Then tell me what I saw."
"I... it's- complicated. You wouldn't understand. I mean, I'll tell you when you get older." Rarity bargained.
"You always say that! I am older! Stop treating me like a foal!" Sweetie huffed. Rarity looked at her. She had grown up a lot recently. Maybe she was right. Maybe she was ready to know the truth about her 'special' sister.
"Okay Sweetie. You're right. I keep telling you that you don't need to keep secrets from me. And I don't want to lie to you, or keep secrets from you either." She sighed. "It's true, what you saw. I did have a penis." Sweetie gasped. She was so sure she was right. But even so, she was still surprised to have it confirmed. "I have a curse." She continued. "Once, every full moon, I grow a penis. And it doesn't go away for three days unless I- um, you've had sex ed in school yes?" She asked. Sweetie nodded. "Yes, well, it doesn't go away for three days unless I have sex with a mare." She paused.
"But as you can imagine, I haven't told anypony else about this. How could I?" She continued. "If any other mare, if anypony knew about my... condition, I'd be the laughing stock of all of Equestria! Rarity the freak!" She cried. "So I have to keep covered up for three days every month to keep my secret. Not that I mind so much. I love dressing up. And so far you're the only pony to discover my secret." She finished as she wiped a tear from her eye.
"But, why not find a mare to do that with and make it not last so long?" She asked simply.
"Sweetie, I couldn't possibly risk letting anypony find out about this. You know how much my friends, and I like to gossip. You really mustn't tell anypony, please?"
"I promise." Sweetie said.
"Thank you." Rarity sighed. After a few moments, Sweetie Belle's face lit up with an idea.
"What about me?"
"Hmm? Oh don't worry, it's not a family curse. You'll be fine."
"No, I mean, I'm a mare. I could help you make it not last so long!" She offered.
"Oh, no, no, Sweetie no! You're just a filly and my little sister besides! I could never ask you to do that! I'll be fine."
"But I want to help!"
"You can help just fine by keeping this our secret." Rarity said.
"I'll go out and find a mare for you then!" Sweetie Belle said.
"NO! Absolutely not! You must Not. Tell. Anypony!" She commanded.
"Then let me help you!" Sweetie punctuated her sentence by hitting her hoof on the table. Rarity ran her hoof through her mane, completely flustered.
"Fine. Ask me again on the next full moon." Rarity said, hoping that she'd forget about the whole thing by then. She was begining to regret the path of truth. 'I should have just said it was a one-time spell. Or once a year. Damn!'
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The next month went by much quicker than she would have liked. The calender said it was the night of the full moon. She watched the sun creep lower in the sky. Sweetie knocked at her door.
"Come in." Rarity called out. Sweetie stepped inside, hazarding a glance under her sister. "No, not yet dear. After the moon rises." She said. The last sliver of the sun slipped below the horizon as Rarity crawled onto her bed. Sweetie Belle waited in the chair beside her. The full moon came up above the tree line, bathing the room in a eerie pale light. Rarity rolled onto her back, spreading her legs. She felt a bit lewd exposing her marehood to her sister like this. But after just a moment a faint aura surrounded the unicorn, focusing more brightly on her nethers.
Sweetie Belle watched in awe as her sister's clitoris began to swell and enlarge. It grew longer and thicker until at last it was the full size of a stallion's penis, complete with a pair of testicles. Underneath, her marehood had vanished. If not for her slender frame and feminine face, she was otherwise a stallion.
"Did that hurt?" Sweetie asked.
"Hmm? No. It's just, nghh," Rarity adjusted her new self with her hoof. " a bit uncomfortable. But it only lasts three days."
"Normally." Sweetie amended.
"Yes. Normally." Rarity said. She waited for Sweetie to chicken out and leave and forget about this whole thing. She hoped that the sheer size of it would scare her off. But she just stayed and looked at it. Rarity was getting quite uncomfortable. "So, um, yes, now that you've seen it, you don't have to-"
"I'm ready." Sweetie said.
"You don't have to do-"
"I'm ready!" Sweetie said again. Rarity looked at her. She was determined. She hesitated but finally spoke after a long moment.
"Okay. Um, why don't you come over here on the bed then." She instructed. She climbed onto the bed beside her.
"C- can I touch it." She asked.
"Um, sure if you want I suppose." She said. Sweetie put her hoof out, touching Rarity's shaft. It twitched a bit at her touch, causing her to jump. It was the first time anypony else had touched Rarity's privates, as a mare or otherwise. "Uh, well, let's not make this take any longer than it needs to." Rarity said anxiously. "Why don't you come stand over me?" She said. Sweetie did as she was told. She straddled Rarity, looking behind her. Rarity took her shaft in her hoof and angled it upwards at Sweetie's bottom.
"Okay now," Rarity said. "Go ahead and back up slowly onto it, so that way you can stop if you feel any pain." Sweetie lowered herself down onto it. She felt the broad tip against her virgin marehood. Rarity already had a bead of precum at her tip. She worked it around, helping to get Sweetie wetter. She put her free hoof on Sweetie's waist, applying a gentle pressure downwards. Her lips spread wide around her thick shaft as she pushed down onto it.
After a long moment, the broad head of her dick slipped inside the filly. Sweetie gasped, as her eyes watered a little. It was bigger than she thought that it'd be. She took another breath, making up for the one she didn't know she was holding. She hid her wet eyes. She couldn't let Rarity see or else she'd make her stop.
She pushed herself down a little more. Now that her head was inside, it was easier now. But after getting less than half way she felt a pressure. She was full. And she could go no further. Sweetie felt disappointed. She hoped that she would be able to do better. But the look on Rarity's face told her she was doing just fine. She looked up at her.
"Are you ready?" She asked. Sweetie nodded. Rarity let go of her with her hoof and laid back. Sweetie felt herself being held by Rarity's magic as she felt herself being lifted and lowered on her sister's cock. She was amazed, watching it slid in and out of her. It even felt pretty good. But it was otherwise boring.
After a minute or two, Rarity started moving her faster until at the very end she pushed down one last time. It was a little harder than Sweetie was comfortable with. She could feel herself being stretched inside as her cock flared. Then it happened. She could feel Rarity cumming inside her. It was the strangest sensation, feeling the liquid spurting into her. And then, just as soon as it started, it was over.
Rarity pulled her off and set her down on the bed beside her. After a moment, her penis became soft and started to shrink. Just as before, but in reverse, it transformed back into her normal marehood. Rarity smiled wide.
"Oh thank you Sweetie!" She said, hugging her sister tightly. "You have no idea how happy you've made me!" Sweetie felt the semen oozing from her backside.
"Am I going to have a foal now?" She asked nervously.
"What? Oh, no dear. My cum can't get a pony pregnant. So you don't have to worry." She said before yawning. Sweetie joined her yawn.
"Rarity?"
"Hmm?"
"Can I sleep in you bed tonight?"
"I guess so. But just for tonight okay?"
"Mhmm." Sweetie agreed, snuggling against her special sister.
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The next three days were a blissful gift of freedom for Rarity. She was free from the burdens of her curse that month. What was once three agonizing days had become less than an hour. The rest of the month passed normally for them. Neither mentioning that night. The night of the next full moon approached. Sweetie stood in Rarity's doorway.
"Full moon tonight." She said as she climbed into Rarity's bed.
"Are you ready?" She asked. Sweetie nodded. Nothing else needed to be spoken. The moon rose. Rarity changed. Sweetie helped her sister. She was again frustrated by how little she could take of her sister though. Afterwards she broached the subject to her.
"Rarity, I want to help you more."
"Oh Sweetie, you're already a tremendous help to me by doing this. You don't have to do anything else."
"But I mean I want to be able to... take more." She said. Rarity looked confused. "More of you... Into me." She said finally.
"Oh, OH! No no, Sweetie you don't need to do that. I'm just fine like this."
"But I want to." She said. "I want to practice for you. Could you buy me a... a toy.' She asked sheepishly.
"I, I suppose I could if you really want one."
"Could you get one that is... your size?" She asked.
"Yes." Rarity said. She actually had, in fact already gotten one that was her dimensions. In a fit of curiosity, she had taken her measurements and bought one her size. Then she wanted to see how she'd feel on herself.
It was good.
She felt a bit strange sharing her toy with her sister. But as she looked at her there beside her with her semen still leaking from her haunches, it seemed like a trivial barrier. She reached under her bed and brought out a long box and opened it. Inside was the rubber phallus replica. She closed it and passed it over to her.
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Sweetie was adamant about being able to take all of her sister. Every free moment she had at home, she sat on the toy, trying to press more of it into her each time. She sat on it in lieu of a chair while she read or did homework. She made small marks on the side with each advancement closer to bottoming out.
By the time the next month rolled around, Rarity was able to slip her medial ring inside her little sister. It was a wonderful sensation for Sweetie Belle too. Feeling it popping in and out of her over and over. She could feel a pressure building in her tummy. And it was her sister's dick filling her. A few more thrusts and she felt herself shudder on top of Rarity. It was her first orgasm. Her filly pussy sprayed her mare cum down her shaft, soaking her fur.
Rarity was unsure how to feel about it at first. This was just about ridding her of her curse. But it had become their special time. Sweetie deserved to feel good for being such a big help. She laid Sweetie Belle down on top of her, hugging her close. Holding her with her hooves, instead of her magic, she humped up into her more slowly with her hips. It wasn't just achieving and orgasm for Rarity anymore. She made love to her.
After a couple more months, Sweetie Belle finally did it. She sat on the toy and felt her rump resting on the floor around it. She got it all the way inside her. And it was just in time for this month's 'special night' as they called it. She couldn't wait to surprise Rarity.
This time, Sweetie took charge, instructing Rarity to get on the bed. The moon wasn't up yet as Sweetie already straddled her sister. Even after everything, Rarity still felt a little strange having their marehoods touching one another's. She wanted to ask what she was doing.
"Shhh." Sweetie said, putting her hoof to her lips. She looked out the window as the full moon rose. She felt the magic in her sister between her legs begin to tingle. She kept herself seated firmly on her lap. She felt her begin to grow and transform. Again, it started out small and grew bigger. She adjusted herself, making sure it went inside her. She felt her sister's penis grow and expand inside her while she kept their hips joined.
Beneath her, Rarity's head rolled back and forth. It felt phenomenal! As she got bigger inside of her, she felt tighter and tighter around her. When she finished growing, she looked down in amazement. Sweetie Belle was still sitting against her lap.
"Surprise!" She said gleefully. "I can take it all now!" She demonstrated by hopping up and down. She looked down at herself sliding in and out of her little sister. It was over half the length of her torso. Rarity's massive dick bulged through the front of Sweetie's tummy each time she bottomed out inside. Sweetie could feel her sister's cock pushing up into the bottom of her ribs. It had taken a lot of work and stretching and internal organs being rearranged, but she did it! And the smile on Rarity's face made it all worth while! She hopped off of her before she could finish. Rarity gave her a look of disappointment. She got on the bed next to her, on all fours, waving her flank at her.
"You can be on top now! You can do it as hard as you want and it won't hurt." Sweetie said. The thought of ever being on top had never occurred to Rarity. And certainly not like this. Slowly, Rarity got to her hooves on the bedspread. She stood over Sweetie Belle, and carefully guided her shaft into her. She'd never tried this angle before. She didn't need to use her magic to hold her. All she had to do was buck her hips like a stallion. It was very liberating. But more than that...
It was empowering.
Rarity no longer felt shame in her penis. She felt good about it. She felt proud even. Her slow thrusts sped up into more powerful humping, sinking all the way inside her sister. The larger of the two, her hips slammed into her sister's, forcing her downward. Her smaller legs couldn't hold the extra weight and gave out. Her hind end was held up, impaled on the penetrating shaft as her face was pressed down into the bedding. She was a bit nervous at first, but she scooted forward a bit and was able to breath as she lifted her head a bit. Above her, Rarity was happily pounding away, grinning as she felt the strength of a stallion running through her.
Sweetie Belle could see her sister smiling in the bedroom mirror. She wished that they could have their 'special sister time' more often than just once a month. She was so proud that she could help her big sister. It was something that only she, and nopony else, could do. It made her special. She could feel her sister cum inside her. There was a flash of magic. The image of a rooster and a stocking appeared on her flank. It was her cutie mark!
She was so happy.
Author's Note
Inspired by http://fruitymilk.co.uk/tagged/SFW
