Author's Notes:

Warning: contains stuff you shouldn't try at home.

The couch was quite comfortable, but for Rarity it was like sitting on a bag of nails. It wasn’t her favourite chaise longue. It wasn’t even her second favourite couch. Luckily, Pearl went back home and Sweetie Belle decided to go and visit Apple Bloom, but still, Rarity had yet another sister she had to deal with.

The sister who was currently sitting next to her with the most innocent expression she could muster.

“So… Umm…” Rarity muttered.

“Yeah… Well…” Sparkler replied, avoiding Rarity’s gaze.

“I was just… Well…” Rarity sighed, looking for the right words. She didn’t find any, so she decided to wait for Sparkler to come up with something.

“Okay…” Sparkler sighed too and shrugged.

Fifteen minutes passed in silence. Rarity stared at Sparkler. Sparkler stared back. Then they both looked at the opposite wall of the boutique. A lonely fly landed on a piece of fabric laying on a nearby shelf.

“Okay, that’s just stupid…” Sparkler said. “We need to talk about it… Make something out of it…”

“What do you want to talk about?” Rarity asked. “My mother–“

“Our mother…”

Rarity sighed and sent Sparkler a nasty glare. “Our mother just came here and told me that the unicorn mare I, umm…”

“’Had an intercourse with’?” Sparkler prompted.

“…the mare I had intercourse with is my sister,” Rarity finished. “What can I make out of that? I don’t usually lower myself to such language, but that’s just fucked up! There’s no other word for it.”

“You don’t usually lower yourself to such language?” Sparkler chuckled. “And who told me to lick her–“ Sparkler gagged when Rarity put her hoof in her mouth.

“Shut up, darling,” Rarity said. “Don’t you get it? I slept with my sister. Everything I earned… My reputation… It’s RUINED!” She stared at Sparkler madly, causing her to jump back on the other side of the couch. “I’m shamed forever! I’m going to shave my mane and go into exile to Stalliongrad! Nopony knows me there!”

“May I interrupt you?” Sparkler asked, raising her hoof like a foal at school. “Before you, umm, do something you’ll regret?”

“It’s all ruined!” Rarity threw herself on the couch. “I’m dead! Eaten and shi– I mean, spat back! I can as well burn this whole place down! Maybe I’ll do that! Sparkler, don’t you imagine what will happen if someone hears that I had sex with my sister? They’ll think that I hurt Sweetie Belle!!! Chris Hoofsen won’t let me live…”

Sparkler rolled her eyes. “I swear, it’s the last time I get out of home without valium…” she muttered. “Equestria to Rarity!” She shook her head, seeing that her new sister was still crying in the couch. Worse, she was wallowing in pity. Sparkler had enough. She caught Rarity and forced her up. “Listen to me!” she yelled, fire burning in her eyes. “I’ve just learned that my parents left me for over twenty years! I’ve learned that I have two sisters! So listen to me for once, or I’ll unleash the rage burning into me on you! And even if you try a safeword, I’ll force it back into your throat so hard that you’ll have to look for it on the other side of the digestive tract! Get it?”

“Get it.” Rarity immediately stopped wallowing in pity, not to mention crying into the couch.

“Thank you,” Sparkler said. “I don’t know if you noticed, but no one but us knows that we had sex with each other. Well, now I’m not sure since you were wallowing quite loudly, which is probably a family trait, since–“ She saw Rarity’s glare. “Okay… Where was I? Oh, I know. My point is, we can make it our secret. We are friends, we had a sleepover, we drank some cider at the bar, we both fell asleep in separate beds, with our hooves on the blankets, and nothing sexual ever happened. It still doesn’t explain why two of your couches are now stained with your various bodily fluids, but still it’s better than the truth.”

Rarity nodded and sat on the couch next to Sparkler. “I need lots of ice cream,” she muttered. “And chocolate. And valium…”

“Hey, I wasn’t that bad!” Sparkler exclaimed.

“Didn’t we just agree that it’ll be our secret?” Rarity asked.

“Yes, but still… That was my best ride in ages…”

“Ride?” Rarity exclaimed. “You call it a ‘ride’? What am I, a bicycle?”

“A bicycle? Never,” Sparkler said, raising her hooves. “Though that actually reminds me of my ex. She was like Rainbow Falls.”

“She was that pretty?” Rarity asked.

“That too, but it’s not exactly that. You know, everypony was in Rainbow Falls…”

Rarity chuckled. “Still, having twenty percent of a good business is better than being the only owner of a bad one…”

“Yeah…” Sparkler muttered. “Too bad, I didn’t even own a one percent…”

Rarity looked at Sparkler with a flicker in her eyes. “Since when we’re talking about your exes?”

“Since we stopped talking about us accidentally getting into incest…” Sparkler replied. “Though, on the other hoof…”

“What’s on the other hoof?” Rarity asked.

“Three things, actually. So, that’d make, like, three other hooves?” Sparkler shrugged. “Metaphors limit my brain, really… Anyway, first of those other hooves is that we didn’t know we were sisters, so it doesn’t count as incest…”

“Fair point,” Rarity replied. “Well, that was what the reasonable part of my brain was telling me when I was wallowing…”

“Then why did you even wallow?” Sparkler looked at Rarity unsurely.

“I rarely listen to that part of the brain,” Rarity said. “You don’t even know how much you can achieve by wallowing..."

“Okay, nevermind.” Sparkler sighed. “On the second of other hooves, we’re both mares. That means no unwanted pregnancy and no genetic fuck-ups with six legs… Though, that’d come in handy if I wanted to make a point that has more on-the-other-hooves than three.”

“Three? Not four?” Rarity asked.

“No. There has to be one hoof so there could be the other.” Sparkler raised one of her eyebrows. “Who even invented that saying? Do you put something on your hooves when you’re talking?”

“Right,” Rarity said. “So, what’s on the third of the other hooves?”

“I don’t care if you’re my sister, I’d totally do that again,” Sparkler replied, smiling sheepishly.

“You what?!” Rarity exclaimed.

“Actually, I’d say that it makes it even hotter,” Sparkler said. “Hey, all that hiding and taboo breaking… That really turns me on…”

“That’s the second stupidest thing I’ve ever heard from my sister, and remember that Sweetie Belle once destroyed a hardware store with fireworks…” Rarity sighed. “I liked it, but I’m definitely not having sex with you again.”

“What was the first thing?” Sparkler asked.

“What?”

“The stupidest thing you’ve ever heard from your sister. You know, I want to know how much I have to train to achieve that level…” Sparkler smirked and leaned closer to Rarity, who winced.

“Oh, it was really silly…” Rarity waved her hoof. “Something about that weird metal that glows in the dark… Sweetie said that if we had enough of it, we’d be able to make more energy than all the unicorns in Equestria together…”

“That’s not silly,” Sparkler said. “I think it’s worth testing…”

“She wanted to do that, but then those weird ponies wearing black suits appeared…” Rarity shrugged. “I don’t remember exactly what happened later. But she also once said that Coco Pommel is a marshmallow zombie…”

Sparkler’s ears perked up. “Who’s that Coco Pommel and can we invite her for a three-way? I’d like to check that hypothesis personally…”

“Well, to have a three-way you’d need three ponies,” Rarity said. “And I’m definitely not going. Also, I guess Coco would have a heart attack after the very mention of it. She’s a delicate girl…”

“Delicate girls are the best…” Sparkler looked at the wall and smiled. “You know? You look kinda like a marshmallow too…”

Rarity sighed and stared at her sister. “Darling, the last guy who told me that got punched through the wall…”

“What?” Sparkler’s ears drooped. “I’ve never thought that you’re so… direct…”

“Oh no, it wasn’t me.” Rarity chuckled. “He was a creep… He licked Rainbow Dash and told her that she tasted like Skittles… Then he woke up on the ER…”

“Where did he lick her?” Sparkler asked, barely containing laughter.

“Where no pony had licked her before,” Rarity replied. “At least she says so – you know what they say about the Wonderbolts trainees…”

“Oh yeah…” Sparkler laughed openly and lowered her hoof, putting in on her thigh. “I’ve seen that movie with the two sisters and that flexible one… You know, she could reach her own…”

“Oh, I remember that one,” Rarity said with a smirk. “That was a really skilled girl…”

Suddenly, they both sat in silence. After a few seconds the silence got awkward. Rarity looked at Sparkler unsurely. Sparkler looked back. They both looked at each other again and bursted into laughter.

“Did we just admit that we like the same porn?” Sparkler asked when she stopped laughing.

“Apparently…” Rarity shook her head. “I’m sure it’s the matter of genes…”

“I hope not,” Sparkler replied, moving her hoof a bit to the south-west. “Think of our little sister and what will happen when she hits puberty…”

“I’d rather not be here when it happens…” Rarity’s eyes widened. “Sparkler, darling, are you touching yourself on my couch? While thinking of our little sister?”

“I’m thinking of that flexible pegasus…” Sparkler smiled sheepishly. “And I’m not touching myself. Not yet. Once I get back home, however…”

“No, darling…” Rarity leaned closer to Sparkler. “You’re still my guest. And I’m not letting my guests leave me unsatisfied…” She kissed Sparkler’s cheek.

“Wait…” Sparkler muttered. “How about all that ‘I’m not gonna fuck my sister’ talk?”

“I still think it’s wrong…” Rarity licked her lips. “But what can I do? It was, as you said, the best ride I’ve had in ages…”

“So, now I’m a bicycle?” Sparkler asked, dodging Rarity.

“I’ll make you my bicycle… Cute and fabulous bicycle…”

“Okay, I’ll pretend that it wasn’t creepy at all…” Sparkler said. “Aren’t you forgetting something?”

“What?” Rarity asked. “Am I too fast?”

“Lock the door. You don’t want your… our little sister to see us, do you?”

Rarity imagined Sweetie Belle entering the boutique and seeing Rarity standing above Sparkler, bound, gagged, and with a foot-long dildo in every orifice Rarity could fit one. She imagined her eyes widening suddenly and her jaw dropping. She could almost hear the sound of her innocence crushing into a million of teeny tiny little pieces.

“I’ll lock the door and barricade them,” Rarity said. “And we’ll go upstairs. And I’ll put something shiny here to distract her and buy us some time.”

“Do that,” Sparkler said. “And then I’ll teach you about the things you have no idea your body can do…”

“How do you know what my body can and can’t do?” Rarity asked.

“Don’t forget that we’re sisters…” Sparkler muttered, spanking Rarity’s flank. “Hey, it’s similar to mine!”

“I wonder what else we have that’s similar…” Rarity said, locking the door.

One quick barricading and a trip upstairs later, Rarity and Sparkler stood in front of a large box Rarity kept hidden under her bed. Rarity aimed her horn at it and opened it. “How do you like that, darling?” she asked.

“It… It’s a…” Sparkler’s jaw dropped. “It’s a giant ruby… Built into a strap-on?”

“Exactly.” Rarity laughed. “You know, I like gems so much and this one was given to me by a close friend…”

“That close?” Sparkler tilted her head, looking at the crystal-adorned strap-on.

“No, of course not,” Rarity replied. “He’s more or less Sweetie’s peer… And I don’t want him to know about this, umm… toy…”

“Sure thing,” Sparkler said. “What’s in this bedroom stays in this bedroom.”

Rarity nodded. “Exactly… You know, I wouldn’t want the whole town to learn that my own sister made me her bitch…”

Sparkler blinked. “Say what again?” she asked.

“Well, when I look at it…” Rarity levitated the strap-on. “I want to be screwed with it. Hard. Without pulling any punches.”

Sparkler smirked and took the strap-on from Rarity, examining it. “Are you sure? It’s… big…”

“Darling, I can assure you that even a lady sometimes just has to do it the hard way…” Rarity replied. “As my sister, you’ll learn that quickly…”

“As you wish…” Sparkler said and rubbed her folds, feeling some juices escaping them. She put on the toy and felt its shorter end sliding into her vagina smoothly, resting on her clit. She chuckled and tried different moves, checking how the crystal appendage looked between her legs. “You know, I should totally go for a walk like that,” she said. “Skirt, saddle, and Mr. Ruby underneath all that. Wonder if somepony would see something strange…”

“Do that.” Rarity chuckled. “They’d think that you were hit with a penis growth spell…”

“Is that even a thing?” Sparkler asked.

“I don’t know and Twilight is weirdly quiet about it…”

“We need to ask her about that,” Sparkler said. “But by then, we have Mr. Ruby…” She patted the artificial penis between her legs. “Get on the bed, sis… We’re gonna take a ride…”

Rarity lay down on her bed, stretching her hooves. “Come on, sister… Let’s see if you really belong to the family…”

“Umm…” Sparkler stood above Rarity, strap-on dangling between her legs. “That sounded as if you wanted to compare me to the rest of your family… D-did you have, umm… with your mom? Dad maybe? Or, Celestia have mercy, little Sweetie Belle?”

Rarity laughed. “That indeed came out wrong, darling… But I can assure you, the only family member I can compare you to are my hooves…”

“Yeah…” Sparkler muttered. “I had the same problem when I was going through puberty. My foster father probably still wonders who stole all those magazines he kept under his bed…”

“Well, darling, today you don’t have to use any aids…” Rarity said, spreading her legs and moving her tail to the side. Sparkler lowered her head and gave Rarity’s pussy a long lick, eliciting a moan of pleasure from her. Rarity wrapped her hind legs around Sparkler’s neck, pushing her face deeper into her marehood.

Sparkler looked up at Rarity and smirked. Even her warm breath was sending small waves of pleasure up Rarity’s spine. She gave her sister’s clit another lick and moved higher, kissing and sucking her teats.

Rarity groaned, shuddering.

“What’s up?” Sparkler asked, rubbing Rarity’s right nipple with her hoof.

“I’m kinda sensitive there…” Rarity muttered.

“Shouldn’t have told me that, sis…” Sparkler assaulted Rarity’s tits with even greater force, causing her body to twitch. She spent a few minutes playing with them, before lowering her face again, burying her tongue deep into her. The smell of Rarity’s juices caused her heart to beat faster. She could feel that the panties dildo was attached to were already soaking. She ran her hoof through her tits and started to play with the gem-encrusted shaft, feeling its other side rubbing her clit, causing even more cum to flow.

“Come on…” Rarity muttered, biting her lip. “Stop playing with it. You have me to play…”

“You?” Sparkler asked absentmindedly, stroking the dildo and smearing her juices all over it. “Oh yeah, I almost forgot…” She tackled Rarity and rammed her hips against her.

“Aargh!” Rarity screamed.

“What?” Sparkler asked, noticing how big Rarity’s eyes suddenly became. “Too hard?”

“No…” Rarity hissed. “Wrong hole…”

“Ah, this…” Sparkler muttered and pulled the strap-on out of Rarity’s ass, leaving the gem-encrusted tip inside. “I can assure you it’s the right hole.” She pushed as deep as she could, causing Rarity to groan.

“Wrong!” Rarity exclaimed between pants, pushing Sparkler away.

“Right!” Sparkler replied, penetrating her new sister’s ass.

“Wrong!”

“Right!”

“Right!”

“Right?” Sparkler paused in the middle of another motion.

Rarity gave Sparkler a nasty glare. “No. Your juices aren’t the best lube.”

“Oh. Sorry,” Sparkler muttered, pulling the strap-on out of Rarity’s ass and positioning it above her pussy.

“That’s not very clean,” Rarity said, watching Sparkler with horror clearly written in her eyes. “I can get an infection if you–“

“Oh, come on!” Sparkler exclaimed. “I bet you have the cleanest ass in Equestria.”

“Well…” Rarity thought of all those things she was doing to keep her posterior white and shiny both inside and outside. She decided that it’d be better not to tell Sparkler about them. She’d definitely get ideas. “I really take care of my hygiene…”

“Good.” Sparkler lowered herself onto Rarity and kissed her. Rarity felt the tip of the ruby sliding between her folds. She shivered in anticipation, feeling the big, artificial cock filling her.

Sparkler smirked and lifted a bit, causing the strap-on to slide about halfway from Rarity’s pussy. Then she lowered herself rapidly, causing Rarity to groan loudly as the tip of the dildo hit the bottom of her vagina, teasing the nerve endings. She didn’t have time to think about it, since Sparkler was holding her in a tight grasp, riding her pussy.

“Maybe… ooh…” Rarity bit her lip. “Maybe you should slow down a bit? Aargh!”

“No way, sis,” Sparkler muttered between pants and moved forward as far as she could. Rarity’s moan ended with a short whimper when the artificial dick plundered her tight orifice.

“Sparkler… I’m gonna…”

“That’s what it’s about…” Sparkler laughed. Rarity’s body twitched and Sparkler felt a stream of her juices hitting the panties her strap-on was attached to, soaking them. She inhaled the pungent smell of her sister’s arousal and, not giving her time to rest, resumed to move.

Rarity groaned, feeling her second orgasm rapidly approaching. She bobbed her head forward and clenched her jaws on Sparkler’s arm, just as her mind drifted away.

“Ouch!” Sparkler exclaimed. “I didn’t knew you like your sex bloody, sister…”

“Oh yeah…” Rarity muttered, breathing heavily. “Bloody, dirty, and with limbs lying at least six feet apart from each other…”

“Well, I’m not sure if I can provide that…” Sparkler laughed. “Also, you may need your hooves in the future. If only to spread them when seeing me…”

“I think we’ll have to tone it down…” Rarity laughed. “Our sister may start to suspect something…”

Sparkler winced. “I almost said that she may join us, but then I remembered how old is she. Not that–“

“You’d better not finish that sentence, or I’ll take that strap-on from you and fuck you in the butt till you get rid of all dirty thoughts about her,” Rarity muttered.

Sparkler hissed. “Well, that ruby looked rather sharp… Let’s see…” She pushed as far as she could, catching Rarity off-guard. Soon, however, Rarity rolled on the top of her, biting her arm once again and riding her furiously.

“Rarity... Stop…” Sparkler muttered between moans, rolling on the bed to be on the top again. “I’m… gonna… Aargh!” She felt her own juices soaking her fur and panties, leaking down and staining Rarity’s white coat. She closed her eyes, twitching as the climax took over her body. The strap-on slid from Rarity’s pussy as Sparkler lay down next to her, panting.

“That was…” Sparkler wiped her forehead.

“Awesome?” Rarity asked. “I sound like Rainbow Dash, don’t I?”

“Well, I don’t know how she sounds like after sex…” Sparkler laughed. Suddenly, her laughter stopped when she stared at the strap-on, still dangling between her legs.

“What’s wrong?” Rarity asked.

“It slipped…” Sparkler muttered, her eyes wide.

“What slipped?” Rarity shuddered when she looked at the tip of the strap-on. She immediately saw what was missing.

“So, it’s probably…” Sparkler looked at Rarity and made a move as if she wanted to spread her folds and look inside.

“Yeah…” Rarity muttered in monotone. “Feel free to look for it… It was you who left it there, after all…”

“Hey, it wasn’t my fault!” Sparkler exclaimed, spreading Rarity’s pussy lips with her hooves and taking a look inside. “I can’t see it…”

“Well, darling…” Rarity said. “I think there’s only one right thing to do now…”

Nurse Redheart trotted slowly to the door. She was just having a really nice dream after falling asleep on the couch in the social room and she was ready to tell anypony who dared to disturb her where they can go and what can they do to themselves.

She opened the door and saw two unicorn mares, smiling sheepishly at her. The smell was the first clue – since she was an experienced nurse, Redheart could easily guess that it wasn’t going to be a normal visit. Apparently, the fur of one of the mares was still soaked in something foul.

“Good evening,” one of the mares said. Nurse Redheart recognised her and her eyes widened immediately. That definitely wasn’t going to be a normal night. The Bearer of Element of Generosity in her hospital? With another mare? Smelling like a bedsheet in a brothel?

“We have a problem,” the other mare said.

“I see…” Nurse Redheart muttered. “What object and which hole?”

Rarity opened her eyes and looked around. The room she was in didn’t look like her bedroom at all. The green walls and completely unfashionable curtains convinced her that she was in the hospital.

“Wait…” she muttered to herself. “So, that whole thing with Sparkler being my sister wasn’t a dream?”

The door opened and Rarity saw Twilight, Applejack, Fluttershy, Pinkie, Rainbow Dash, and Sparkler entering her room. Sparkler was smiling sheepishly, walking behind the rest of Rarity’s friends. Twilight’s eyebrows were furrowed, but the rest of her friends seemed relaxed – they were chatting happily, as if they weren’t noticing Twilight’s expression.

“I’m glad you’re okay, Rarity…” Fluttershy said, walking to her bed.

“Wait, you mean that… thing?” Rarity asked.

“Oh, you don’t remember?” Pinkie smiled. “I can tell you about everything. First you were screaming and saying words I didn’t know you knew, then you asked the doctors about the anaesthesia…”

“Okay, I get it,” Rarity muttered.

“By the way, Spike is still in Berry Punch’s bar,” Rainbow Dash said. “He can’t get over the fact that you preferred–“

“What?” Rarity looked at Sparkler who shrugged.

“You don’t remember anything?” Sparkler asked. “Geez, I need to ask the doctors what they put in that stuff…”

Suddenly, Rarity remembered everything. The whole thing with Sparkler and Nurse Redheart really happened – eleven months before. Nurse Redheart couldn’t find the lost ruby and soon Rarity started to…

Just when Rarity was slowly realising what happened, the door opened again and one of the nurses came in, carrying something wrapped in a blanket. “Congratulations,” she said, giving it to Rarity. “It’s a filly!”

“Oh…” Rarity muttered, staring at the little, ruby-coloured crystal pony in her hooves. “I…” She looked at Twilight, who was still frowning. “What’s going on?” she asked. “Is it about Spike?”

“No,” Twilight replied, smiling at her. “I’m not mad at you, Rarity.” She sighed. “I just feel that I really need to talk to Cadance about her guards…”