If she had been asked back when she was a male guard, she would have said that the boredom of standing watch was one of the worst things about the job. Today, though...

Today, a little boredom was something that Gleaming sorely missed – something she could truly appreciate. So far, it had just been a perfectly normal guard shift, with nothing notable happening. Her report paperwork at the end of the day would be full of 'On duty – nothing to report' entries every hour, on the hour.

She'd been assigned to stand watch over the entrance to the visiting dignitaries' wing of the palace. As she stared down the hallway and watched nothing continue to happen, she wondered whether Cadance might have had something to do with her assignment here. After all, she and Twiley were the only two 'visiting dignitaries' currently in residence. Had Cadance gotten her placed here so that she could toy with Gleaming? It was a possibility. Cadance seemed awfully amused at Gleaming's predicament... It was a little irksome. This was a serious problem. Cadance wouldn't be giggling behind her spouse's back if she had been the one gender-flipped!

The sound of footsteps approaching from behind made Gleaming flinch – was she really that on-edge? This unfamiliar and oversensitive body had her rattled!

When she turned to see who it was, though, she recognized her sister immediately. “Twilight!” she said, smiling. “It's so good to see you!”

Twilight paused, looking at Gleaming askance and with a raised eyebrow.

It took a moment – an embarrassingly long moment – for Gleaming to realize that Twilight hadn't recognized her. If Gleaming had spoken like that to any of the other princesses, she'd be getting reprimanded right now. And even though Twilight was obviously rather lax when it came to official greetings, Gleaming realized with a sinking feeling in her stomach that she'd quite nearly just blown her cover. “Er, um...” She cleared her throat. “I mean, good afternoon, Princess Sparkle.” Giving her best military composure a workout, she stared straight ahead at the empty hallway, showing no expression or emotion whatsoever.

Was it the effort of adjusting to this new body that was making her mess up so easily? She'd never once had a slip-up like that in her days as a guard. With a renewed effort of will, she forced herself to stay focused on the task at hand.

“Oh, okay...” Twilight began walking again, passing by Gleaming on her way out. “Good afternoon to you, too, um... What was your name?”

“Gleaming Shield, Ma'am.”

She nodded politely before continuing on her way. “Good afternoon, Gleaming Shield. It was nice to meet you.”

Just as Gleaming breathed a slight sigh of relief, though, Twilight paused in mid-stride again. She turned back and looked at gleaming, absently rubbing her lower lip with one finger as she gave Gleaming an appraising look.

Gleaming gulped – without showing it, of course. Uh-oh... What was it going to be now?

Instead of continuing down the hall, Twilight came back toward Gleaming. “Say, um... I haven't seen you around the palace before. Are you a new recruit?”

“Yes, Ma'am.” Gleaming nodded cautiously, dreading where this might be going. If she was going to be subject to Twilight's full scrutiny, she might have to start rushing out the made-up details as fast as she could, and she'd better not make a single mistake or contradiction. “I just started today, actually.”

Her eyebrows rose. “They allow fresh recruits to guard such important guests?”

“I transferred in, from the Crystal Empire.”

“Oh! You must have come here with Cadance!”

Gleaming nodded again. “Yes, Ma'am. I traveled along with Princess Cadance.”

“That's funny... You don't look like a crystal pony.” Twilight came closer ... a bit too close, examining Gleaming carefully.

“I moved to the Crystal Empire from, uh...” She couldn't say Canterlot – that was too close to the truth! Twilight might guess who she really was! “From Hoofington. I've been serving in the Crystal Empire guard for years now, but I wanted to transfer back to, um ... be closer to my family.” Well, that was kind of true – Gleaming was very close to one of her family members right now, as it happened. She tried to give a warm, but professional smile. Friendly, but not inappropriate for a guard addressing a princess.

“You must have so many interesting stories from the Crystal Empire...” Twilight leaned against the wall next to Gleaming. It looked like she wasn't going anywhere anytime soon.

“It's, um ... not that interesting, Ma'am. Very little has happened since the Crystalling.” Gleaming tried to ignore the feeling of her unaccustomed clothes rubbing against her ... why did it have to be so distracting? And why was it making her have inappropriate thoughts about her sister? She had to keep those kinds of thoughts out of her head no matter what.

“Oh come on...” Twilight leaned in even closer ... to the point where it was definitely unprofessional. What was she doing? What was going on? She reached a hand up as if to toy with Gleaming's hair, but then lowered it at the last moment, flinching away as if uncertain of herself. “I'm sure you have something to tell me about. Maybe after your shift? When do you get off?”

“I don't get off until sex.” Gleaming's eyes opened wide and she slapped her hands up to cover her mouth. “I mean six! I don't get off until six!” As a little bit of silence stretched between them, Gleaming stood with her very best poker face, despite the heat she felt rushing to her cheeks.

Twilight's own eyes widened a little, and she grinned. She finally broke the awkward bit of silence with, “You know, Gleaming Shield, I can't quite put my finger on why, but I keep feeling like I really have a connection with you...” She wiggled her eyelashes suggestively.

And that's when it hit Gleaming. Of course! Cadance had been giving Twilight lessons on love, right? Twilight must be trying to pick up dates! It all made sense now! It was almost a relief – Twilight wasn't catching on to her disguise; she was just trying to set up some kind of a date with a guard she liked.

As easy as it would have been to simply tell Twilight that she was happily married, Gleaming was curious what kinds of things her wife had been teaching. Just how would Twilight go about trying to pick up the new palace guard, anyway? Wouldn't it be worthwhile to find out? Maybe it would even help Cadance's lessons with Twilight if Gleaming could report back and tell her wife how Twilight had done... The way Twilight looked, with her sleek purple dress and low-cut V of cleavage showing definitely had nothing to do with it. Nothing at all.

“Please,” Gleaming said with a deliberate coquettish lilt and a fluttering of her own eyelashes. “I shouldn't.”

“Oh come on, what's the matter?” Twilight was in the chase now, definitely. She was already giving Gleaming some very alluring bedroom eyes ... and was she wearing more makeup than normal? It was giving Gleaming some very ... uncomfortable feelings about being hit on by her sister. But it wouldn't hurt to continue the experiment just a little longer ... right?

“But I'm just a guard, and you're ... you're a princess.”

“Who cares?” Oh, the way Twilight brushed that serious objection away so flippantly actually did make Gleaming's heart pitter-patter a little. She gave a cute little smile and batted her eyelashes again. “I don't know about you, but I'm definitely willing to make an exception for a mare as—” she looked Gleaming up and down “—exceptional as you.”

Gleaming tried to tamp down the rising heat inside her, but it wasn't entirely successful. It wasn't just the flattery, it was something about her sister's gaze that told her that Twilight really meant it.

“Why don't you take a little break?” Twilight whispered, barely loud enough to hear. “We could get to know each other a little.”

This was starting to go too far, Gleaming was sure. Why was it so hard to breathe? She ... she shouldn't be feeling this way with her sister! As she nervously shifted her legs a little, she felt a bit of wetness in the red lace panties her wife had put on her. Oh Goddess, was she getting wet at the thought of ... doing that with her sister? She gulped, entirely failing to hide it from Twilight. “I can't until I get off – I mean until my shift ends!” Ugh! Why did she keep saying things like that? Was this just a Gleaming thing? She'd never done things like that before, and certainly not with her sister.

Twilight's eyes went wide when she heard that. She even blushed a little herself. But then she moved in to close the deal, edging up so close to Gleaming that their breasts nearly touched. “My, my ... you don't look so good.”

Gleaming could barely breathe. When she spoke, it came out as a kind of a squeak. “I... I'm fine.”

“Maybe you should get off before six ... several times.” Twilight gave her a very knowing look.

The heat was rolling over Gleaming in sultry waves. Where did Twilight learn to be so ... assertive? Why was it making Gleaming so hot and tingly? Was Cadance really that great of a teacher?

“Just look at you... You're red and sweating, and your breathing is so rapid...” Twilight leaned in even closer; her hot breath on Gleaming's neck didn't make things any easier. “... and if your nipples get any harder, I think they're going to poke through that armored breastplate.”

A shiver ran down Gleaming's back. It was true. It was so true... How did she know?

“I'm afraid I'm going to have to invoke my authority as a princess and order you away from your post – for your own good. You obviously need to be relieved, for your own health. Why don't you come back with me to my suite? We'll get that restrictive armor off you and give you a nice, thorough checkup. I'm sure you'll be felling really amazingly good in no time...”

“I can't,” Gleaming objected. “I'm—”

But Twilight was already taking Gleaming's hand and beginning to lead her back down the hall. Gleaming resisted the gentle tug at first. She could have stood her ground and stayed right where she was. She should have. But she didn't. That gentle pull was somehow irresistible ... or was it the way Twilight's legs moved in that silky purple dress?

As much as Gleaming wanted to pretend she didn't feel that way about her own sister, there was no denying it at this point. By the time they reached the end of the short hallway and made it to the door of Twilight's suite, Gleaming couldn't tell if her breath was coming short because of lust or because of panic. She really shouldn't be doing this!

Twilight opened the door, stepped just inside it, and gave Gleaming a sultry look that felt like it could have melted the armor right off of her. That gentle hand tugged her onward again, oh so softly...

But this time, Gleaming stood her ground. Somehow, she knew this was her last stand. If she went in there, if she was alone with Twilight ... there would be no going back from that. There would be no way she could resist. Cadance had told Gleaming to 'have some fun', but did that mean she had permission for this kind of fun? Cadance couldn't possibly have meant that ... could she? It was tempting – oh so tempting – to think that she did have permission.

If Twilight had simply pulled Gleaming's hand harder, that would have been possible to resist. But no... Instead, she gently caressed Gleaming's palm with her fingertips, all the while giving her that look – that 'I know you want me' look. It was pushing all of the right buttons, making Gleaming's whole body tingle with suppressed desire.

Gleaming took a step forward, into Twilight's suite.

Once she was in, Twilight quickly shut the door behind her ... and that knowing look was replaced by a sexy, gleeful grin. Twilight darted forward; Gleaming pressed her back against the closed door, trying to retreat. But that was just what Twilight wanted – she pinned Gleaming against the sturdy wooden door by pressing with her entire body. Gleaming's legs felt weak as she saw her sister's tits pressing against her breastplate, as she felt her sister's hands exploring up and down her body, as she saw her sister's face come closer and closer with a heated look that could only mean one thing...

When the kiss came, Gleaming melted into it willingly. She might have fallen if Twilight wasn't pressing her against the door with her body. Twilight's lips just lightly touched hers in the beginning, but that changed at the sound of the first slight moan Gleaming let out. It seemed to invigorate Twilight, to urge her on. She pressed her lips more firmly to Gleaming's, letting her feel the soft heat and the desire. When Gleaming finally began returning the kiss a little, Twilight took the initiative again, plunging her tongue into Gleaming's mouth without any sense of asking permission. She was taking what she wanted from Gleaming ... and why was that making Gleaming so incredibly aroused? She couldn't stop herself from moaning more deeply and sucking on Twilight's tongue like she was trying to fellate it.

The two of them separated for a moment, a thin strand connecting their mouths before it snapped. Now, when Twilight grinned at her, she seemed to know not only that Gleaming wanted her, but also the way Gleaming wanted her. She pulled Gleaming away from the door and sent her toward the suite's bedroom. “Get in my bed, now,” she ordered, her horn beginning to glow.

Twilight's magic curled around Gleaming's clothes as she stumbled toward the bedroom in a cloud of lust. By the time she made it to the door, most of the lacings had already been undone, and much of her armor was floating next to her rather than remaining attached. Her skirt unbuckled and the padded undershirt beneath the armor slipped forcefully over Gleaming's shoulders. A touch of magic pushed her, and her legs hit the edge of the bed. She fell down on it just as her armor and clothing were tossed in a heap in the corner of the room. Twilight had left her with only the lacy red bra and skimpy panties.

And Twilight herself loomed over her, eying her appreciatively, still fully clothed. “Aren't those lovely,” she said. “Do you wear things like that every day, or were you hoping some visiting dignitary would come and whisk you away?”

For some reason, Gleaming felt it necessary to cover herself with her hands as well as she could, blushing hard. She realized that Cadance had probably dressed her like this knowing that something might happen. But she couldn’t possibly have intended for it to happen with her sister!

Twilight reached down and grazed a finger across Gleaming's bare thighs. “Oh come on, now ... don't hide yourself. It's obvious you were hoping someone would see you like this.”

Gleaming twitched and gasped at the sound of Twilight's voice. Why did it affect her like that?

“Now ... why don't we get those off of you?” Twilight's horn glowed again, brightening the dim room.

Before Gleaming knew what was happening, the clasp of her bra magically unfastened. Her tightly confined breasts immediately came free, bouncing outward a little. And Gleaming could see the slight gleam in Twilight's eyes as she saw that. Maybe it was time to play a little? Gleaming held her hands over the cups of the bra, holding it in place and looking up at Twilight with her best impression of an innocent little virgin. “You... You want me to take it off?”

“No...” Twilight edged in closer, leaning over the bed and reaching out a finger to hook around the small strap between the two cups. “I'm taking it off.” She pulled, and with a little assistance from her magic around the other straps, the whole thing slipped out of Gleaming's grasp, leaving her exposed as her arms were forced out and together to slip the straps off.

She would have rushed to cover herself with her hands again, but Twilight beat her to it, grabbing huge handfuls of her tits with both hands, squeezing them, rubbing their nipples, and pushing them up and together on Gleaming's chest.

Gleaming couldn't help herself. She moaned as Twilight toyed with her bare breasts; she could barely keep herself from begging for more as Twilight pushed her down on the bed, ending up straddling her mostly-nude body. The skirt of Twilight's gown bunched up over her thighs, and Gleaming couldn't help but stare down at the glimpses she got of that between her sister's eagerly-working arms. “Twilight,” she said, ignoring any protocol of proper address, “I can't, I'm—”

Twilight leaned down and kissed her again, deeply and wetly. The objections were cleaned right off of Gleaming's lips before they could make their way out, and Gleaming finally gave in. She reached up above herself, touching Twilight through the gown – the wide swell of her hips, the long sleek curves of her sides, the alluringly plush swelling of her breasts. Gleaming couldn’t feel much through Twilight's gown and bra, but the sheer size of Twilight's endowments surprised her. She'd seen Twilight naked once before, long ago, when they were growing up together. It had just been a mistake, walking in on her in the shower, and she'd only gotten a small glimpse of her sister's breasts back then before quickly ducking out. A lot of shouting and weeks of awkward glances between the two of them had followed, but for some reason, that image had stuck firmly in Gleaming's head right up until this very day. Twilight's breasts were much bigger now... Was that just because she'd grown up since then, or did becoming an alicorn have something to do with it?

Gleaming began fumbling for the tiny zipper on Twilight's gown, suddenly desperate to see her sister naked again, but she didn't manage to pull it down far enough.

Twilight was moving, sliding down Gleaming's body and beginning to lavish Gleaming's tits with her mouth and tongue. Gleaming's fingers trembled and jittered in place at the feeling, taking away any hope she had of unzipping the gown before Twilight continued on sliding down, planting kisses on the bottom of Gleaming's chest, down her toned stomach ... all the way until Twilight's lips met the upper hem of Gleaming's tiny red thong.

And that hem wasn't very high – the panties were cut very salaciously low, barely coming high enough to hide the shallow cleft between Gleaming's pussy lips. She could feel her sister's breath down there, heating her through the soaked-through fabric.

For a brief moment, everything in the universe seemed to hang in perfect suspension, absolutely balanced on the needle point of Gleaming's unspeakable desire for her sister. But then everything came down in an avalanche of debauched lust as Gleaming felt her sister's fingertips slowly trace right down the middle of the soaked red panties.

Gleaming's hips bucked involuntarily when Twilight's finger touched her clit through the thin, silky fabric, but Twilight's hand matched her motion perfectly, staying exactly where she could just barely touch. It was an incredibly skillful touch ... one exactly like Cadance had done earlier, during Gleaming's first time as a mare. Wait... Cadance had been teaching Twilight! Did Cadance teach her this? How would that even happen?

All thoughts of it were driven out of Gleaming's mind when she felt her panties being pulled to the side. No – this couldn't really be happening, could it? Was she really going to let this happen ... with her sister?

Yes. The first touch of Twilight's gentle fingertips on Gleaming's pussy was enough to blow away any thought of stopping this. Why was she so sensitive down there? Even just a little touch on her outer lips was enough to drive her wild with desire, enough to make her legs spasm and shake against the bed.

And it only became more intense from there. Her sister's clever little fingers seemed to be able to touch her anywhere and everywhere at once, teasing her into ever-greater heights of lustful desire. Gleaming thought she might explode on the spot when she felt one of Twilight's fingers slowly begin to slide up inside her, squeezing into the tight opening of her pussy and finding a cozy home inside as it began to wiggle back and forth, touching just the right spots.

Gleaming arched her back and moaned deeply, the distractingly massive tits on her chest heaving up and down with every desperate breath. She clutched at them with both hands; the feeling of having them squeezed just fed back into and intertwined with the pleasure her sister was giving her down between her legs. She could hardly hold it in any longer – she knew it was coming soon. She was just so sensitive – it was like this new body of hers was totally fresh and still on a virgin's hair-trigger.

But then, Twilight slipped one finger out ... then the other. When had she put in another finger? How had the sensations been so intense that Gleaming didn't even notice that?

Twilight's wet fingers instead pulled at the thin waistband of Gleaming's panties, tugging them downward. Gleaming raised her hips a little, helping them slide down her legs and letting Twilight pull them completely off. They were Gleaming's very last scrap of clothing, and losing them left her completely exposed, completely bare in front of her sister. She should have felt shame, should have felt fear or maybe even disgust... But instead, she just felt desire, the burning need to have her sister touch her again, to finally bring her to an incestuous orgasm.

Twilight tossed the panties up on the pillow near Gleaming's head and settled down onto the covers between Gleaming's outstretched legs. She looked up into Gleaming's face over the twin bulges of her tis, and she smiled slightly. “Do you want it?” she asked, her lips so close to Gleaming's pussy that she could feel the heat of Twilight's breath as she spoke.

“Mm-hm!” Gleaming looked down at her and nodded eagerly.

“What do you want?” The teasing tone in Twilight's voice was clear.

Gleaming couldn’t wait that long. “No! Please! I need it – please just do it now!”

“You need it? ... Tell me, just what is it you want from me, and why you want it.”

“Lick me!” Gleaming said desperately. “Please just lick me, Twilight! I need it so badly!”

“Lick you? Lick you where?”

Why did she have to be like this? It was just like when Cadance had done it – had Cadance already taught her this? They'd only been doing lessons for one day! How had they already gotten to this point? And why did her sister have to tease her like this? Why couldn’t she just do it?

“Gleaming Shield,” Twilight said, her breath tickling Gleaming's clit. “Just tell me exactly what you want and why you want it ... and you'll get it. Be a good little slut.”

Gleaming snapped. She couldn't hold it in any longer. “Please please please lick my pussy, Twilight! I'm a slut – I'm a slut for you! Just please put your tongue in my slutty little cunt!”

Twilight smiled up at her from between her legs. “All you had to do was ask.” She winked and then wholeheartedly plunged her muzzle down onto Gleaming's needy pussy.

The contact shot through Gleaming like a lightning bolt, frying her from the inside out with an intense surge of much-needed pleasure. Her pussy had needed this so much that it had felt almost sore as Twilight waited and teased her. But now... Now, now her whole world revolved around her sister's tongue lapping away at her pussy lips and dipping inside to twirl around like magic. Gleaming's hands danced over her whole body which wanted to be touched everywhere at once.

Without taking her mouth fully away from Gleaming's pussy, Twilight pulled back just far enough to speak clearly, her lips still tickling Gleaming's pussy as they moved. “Is that what you wanted, my little slut?”

“Yes! Yes!” Gleaming cried out in return. “Give me everything you— Aaah!”

Twilight had gone right back to it before Gleaming could even finish what she was saying ... and the moment her sister's full attentions were returned, Gleaming didn't want to say anything else. She couldn’t if she'd tried.

It didn't long after that. When Twilight's tongue moved up to her clit, somehow cupping it and rubbing every part of it at once, Gleaming came explosively, her whole body jittering in place as her juices spurted out and marked her sister's face. It seemed to go on and on, longer than any of her orgasms as a male had ever lasted ... and even when it finally began to calm down, a quick insertion of Twilight's finger set her off all over again, turning what would have been a mild aftershock into a desperate finger-squeezing, leg-clenching, and breast-grabbing crescendo.

When the throes of her orgasm finally left her, Gleaming collapsed limply to the bed, struggling just to breathe without passing out. She could barely lift a finger.

So when Twilight brought out some rope from who knows where and tugged Gleaming squarely into the center of the bed, Gleaming didn't even think of resisting. The most she could have managed would have been a feebly questioning moan, anyway.

As Gleaming slowly began to catch her breath and recover, Twilight quickly and efficiently bound up the knots, securing each of Gleaming's arms and legs to the corner bedposts.

By the time Gleaming felt like herself again – as much as she could in this new, hypersensitive body – she found Twilight kneeling over her, tightening the last of the knots on her wrist. It occurred to her that maybe she didn't want to be tied down and put completely at her surprisingly kinky sister's mercy. Her arms and legs were far too securely fastened to do anything with, but she still had her magic. She lit up her horn, beginning to work at the knots. Maybe she'd let herself be tied up someday, but it was definitely something they'd need to talk about and discuss before—

Twilight leaned down and ran her tongue up Gleaming's shimmering horn. The intricate magical patterns warped and dissipated in a shower of sparks as her sister's delicate tongue wrapped halfway around her horn's spirals. And as Gleaming reeled from the slight magical backlash, she felt a small metal ring sliding in place. An inhibitor ring. She could already feel it absorbing what was left of her knot-untying spell, and she knew enough about restraints from her time as a guard to know that even at her best, she probably didn't have enough magical power to overload and shatter any decently-forged inhibitor ring. She was stuck. Why did Twilight even have one of those?

“Can't have you leaving just yet, now can I?” Twilight got up on her knees next to Gleaming, smiling down smugly ... which somehow managed to be incredibly cute. “I haven't had my fun yet!”

With a seemingly effortless flap of her wings, Twilight picked herself up off the bed and stood next to it, where Gleaming could clearly see if she turned her head to the side.

And as soon as Twilight saw that Gleaming was looking at her, she finished what Gleaming had started and unzipped her gown the rest of the way. She didn't just whip it off, though. Instead, she held the now-loose cloth against herself, beginning to dance and sway her hips to some music that nopony else could hear.

Gleaming's eyes went wide. She'd never seen her sister move like that ... and it was beginning to give her a needful feeling in her pussy all over again.

Twilight slowly – oh so slowly – let the gown fall from her shoulders, down her chest, sliding it back and forth against her body as she let it go down. At first Gleaming could only get a few glimpses here and there of Twilight's shockingly bright-pink bra ... but those glimpses grew and built up just like Gleaming's resurgent arousal. Eventually, she could almost always see the generous curves of Twilight's tits cupped in the pink bra ... and more and more, she could see much of Twilight's trim belly exposed bit by bit.

By the time Gleaming caught her first sight of Twilight's matchingly pink panties, she felt like she was ready to burst, already desperate for more ... anything more, as long as it could quench the burning fire growing inside her pussy.

But Twilight wasn't done with her striptease yet, not even when she let the gown fall down her legs and rumple onto the floor. She kept on dancing, putting even more of a swing into her hips now, and coyly letting one of her bra straps fall down her shoulder. Then the other. Without the support, her bra threatened to slip down; it released minutely, letting just a little more of Twilight's breasts slip out of them. Gleaming caught sight of just a little sliver of color that had to be the very upper edge of a nipple.

Suddenly, Twilight paused, freezing in place except for her hands, which came together at the joint between the two bra cups. Giving Gleaming a sly little smile as she did, she twitched her fingers, and the two cups separated ... now the only thing that held them against her breasts were her own hands.

Gleaming's eyes went wide ... and not only at the way those violet boobs moved when they were nearly free from their confinement. She resolved to get herself a bra like that – it would be so much easier to put on...

Any such mundane thoughts were blasted out of Gleaming's head though, when Twilight pulled the remnants of the bra off of herself and let it fall to the ground, spreading her hands apart high over her head as she began to dance again. Those tits! If Gleaming wasn't careful, she was sure that she'd start drooling at the sight of them. They were every bit a match for Gleaming's own ... perhaps a tiny bit smaller, but very nicely rounded and firm-looking. They jiggled and moved a little as Twilight danced, but only a little.

For the first time, Gleaming struggled physically against her restraints. She wanted to touch them! But they were maddeningly out of reach. Was it something about the color, the shape ... or was it simply that they belonged to Gleaming's sister? Why did she want them so much more than her wife's all of the sudden?

The only thing that was able to pull Gleaming's attention away from those bountiful purple breasts was when Twilight tucked each of her thumbs under the front of her neon pink panties, folding the little triangle of fabric forward towards Gleaming and exposing – little by little – the way her belly smoothly curved down and inward, narrowing ... narrowing...

Twilight stopped just when a tiny bit of the cleft between her pussy lips was showing. She paused there, watching Gleaming's eyes. And when she saw the desperation there, she must have known that she'd teased enough, because she flicked her panties the rest of the way down, letting them slide to the floor.

And there, framed by a lovely bit of thigh gap, Gleaming saw her sister's pussy for the very first time. Twilight had been covering it with her hands during the shower incident. Without even thinking about it, Gleaming licked her lips. Twilight's pussy was just so pert and smooth... Yesterday, she would have shuddered at the thought, but now she knew that she'd never be complete unless she could have that. She needed that, and she couldn’t wait for Twilight to come sit on her face, shoving that perfect pussy against her mouth and claiming Gleaming with her drizzling juices...

But Twilight didn't come over to the bed, didn't swing her leg over Gleaming, and didn't drop her pussy down on Gleaming's face. Instead she turned and rummaged around inside a set of drawers next to the bed. It gave Gleaming a fantastic view of her sister's ass and the sweet little pussy lips bulging out between her curvaceous ass cheeks ... but what was she doing over there? Why wasn't she coming to the bed?

A moment later, when Twilight turned around, Gleaming saw it: a rubber horse cock every bit as big as a real stallion's, and already semi-flared at the tip. On the other end was a smaller protuberance and a collection of straps.

“A certain friend of mine taught me that it's important to set up a safe word, both verbal and non-verbal.” She gently inserted the smaller end of the strap-on into her own pussy, spreading the pretty little lips apart a little as it slid inside. “So if at any time it becomes too much for you”— she buckled the straps around her waist and legs —“just say the word 'epistemology' or nod your head up and down three times.”

Gleaming took one more look at that huge rubber cock as Twilight came around and got into place between her legs, then began nodding frantically. “Ephis— Eppistimololly... Uh, Episte—”

Twilight came closer, leaning over Gleaming's body and letting the rubber cock slide up against Gleaming's belly. “Already?” she asked. “Come on – you're a royal guard! I know you can't scare off that easily.” She gave a sultry look, straight into Gleaming's eyes. “And I can tell you want it. You're my perfect little slut now, and you know you want my cock inside you. You know how good it will make you feel.”

Trembling in place, Gleaming nodded once.

“Now, do you really want me to quit, or do you want me to give you all the fucking your debauched little heart desires?”

Gleaming hesitated, her eyes glancing up and down between the tip of the big rubber cock, her sister's lovely boobs hanging down over her own, and her sister's knowing gaze. Twilight's eyes told her that Twilight already knew what the choice would be.

So did Gleaming, for that matter. Squeezing her eyes shut, she blurted out, “Yes, do it! Shove your big cock inside my slutty little pussy!”

That was all Twilight needed. Sliding back down Gleaming's spread-eagled body, she lined the tip of her strap-on up against Gleaming's pussy and immediately shoved it inside.

If Gleaming hadn't been so soaking, sopping wet, it probably would have hurt ... but the broad tip of Twilight's rubber cock glided easily inside, spreading Gleaming's pussy lips open wider than they'd ever been before as if it was nothing. Twilight gave another thrust, and a huge portion of the shaft slid inside, swelling Gleaming from the inside out in a way she'd never experienced before in her life.

Gleaming wanted to reach up and grab her sister, to hold her close and clench her legs around Twilight’s back, but the ropes kept her exactly in place as Twilight hilted her strap-on. The two of them paused for a moment, desperately breathing as they both came to terms with the other's body.

Twilight recovered long before Gleaming did, though. She moved her hips in long, rocking motions that thrust the false cock deep inside Gleaming every time, rippling its rubber veins over Gleaming's inner walls with its every motion. And as things slickened even more, Twilight grew bolder, pounding into Gleaming's pussy recklessly, slamming their hips together with a clapping jolt over and over again.

Gleaming hit her next orgasm before she was even aware that she was building up toward it. Her body spasmed as much as it could between the ropes, milking Twilight's rubber cock as it continued pushing inside her over and over. Twilight obviously knew Gleaming was getting off – the pitch of Gleaming's moans made that obvious enough – but she kept on going, not stopping for a moment, which only made the orgasm extend longer and longer.

And even when Gleaming finally went limp, Twilight only increased her pace, beginning to breathe heavily herself as her tits swung back and forth above Gleaming's chest.

Gleaming never had a chance to recover from her orgasm. Instead of decreasing and dissipating, her pleasure only grew and grew, until it washed over her in overwhelming proportions. She couldn’t stop the sounds coming from her mouth now – a mixture of raucous screams, deep moans, and cries of “Yes! Yes! Fuck your slut! Fuck me, Twilight!”

“Oh no you don't,” Twilight said. “You don't get to talk. That's not what you're here for.” With her magic – and without pausing in her intense rhythm – she levitated Gleaming's panties and stuffed them into Gleaming's mouth, mid-scream. Gleaming let out a muffled yelp of surprise, then another deep, reverberating moan as she felt Twilight wrapping a strand of ... something between her lips and around the back of her head. It turned the panties into an effective gag.

“How do you like the taste of your own pussy?”

Gleaming tried to say that it was too much for her to handle, that Twilight was going too fast and too hard for her ... but it just came out as a mumbled mess.

“Yes...” Twilight's punishing pace grew even more intense. “You like it, don't you?” Even as beads of sweat started appearing on her brow, she managed to spare the energy to roughly grope Gleaming's tits, her fingers pressing deep into the soft flesh before moving up to pinch Gleaming's nipples almost cruelly hard. All the while, her thrusts grew more frantic, her face redder, until she, too was moaning and beginning to tremble.

“I'm going to get you assigned to my personal guard,” Twilight said, slamming her cock home inside Gleaming's pussy. “It's going to be your new permanent assignment, and I'm going to keep you very close.”

“Mmm...” Gleaming strained against the ropes, wishing she could get even closer right now.

Encouraged by Gleaming's reaction, Twilight continued, “Let's see you keep your bearing and stand at attention with a remote-controlled vibrator deep, deep inside your slutty little cunt. I'm going to set you up for an inspection and turn it up to the maximum just as your commanding officer comes up to you.”

“Mmm!”

“And maybe, if you're really good, I'll put one up your ass as well!”

“Mmm!”

Twilight somehow became even more rough with her thrusting, making Gleaming's pussy sparkle with shimmers of pleasure all over. With each rough slap of flesh against flesh, she let out another syllable. “And I'll make a lit-tle alt-er-at-ion to your un-i-form: a coll-ar that says 'Prin-cess Twi-light's Per-son-al...” She gave one final, brutal push. “... Slut.”

At that very moment, Gleaming came again, her pussy clenching down hard on Twilight's strap-on, her whole body roiling with the reverberations of Twilight's words and Twilight's wonderful rubber cock filling her nearly to the point of bursting.

Twilight tried to keep going, but the way Gleaming's pussy was squeezing down on the strap-on must have made the other end of it move differently inside her, because after just a couple more thrusts, she stopped in place, her own body jittering and her chest heaving as her own orgasm hit. Her body collapsed against Gleaming's, and she squeezed the other mare tightly against her as both of their bodies convulsed against and – in a way – within each other. Twilight's muzzle tucked tightly into the crook of Gleaming's neck, her breaths blowing hotly against the base of Gleaming's mane.

It was all perfect ... or nearly perfect. Gleaming was desperate to wrap her arms around her sister and squeeze her tight as both of their orgasms began to fade and calm, but the ropes held her fast, preventing her half of that incestuous embrace.

When Twilight – trembling and weakened – finally pulled her strap-on out of Gleaming and untied the ropes with a flick of her magic, it was all she could do to roll off to the side and breathe.

Gleaming finally got that embrace she wanted, rolling over in turn – barely even bothering to remove the panty-gag from her mouth – and pressing herself close against her sister. Their warm breasts mashed against each other, but she pulled her sister in tight anyway, desperate to feel close. For a moment, she almost admitted to Twilight who she really was ... but no. That might ruin the moment, and the last thing she wanted to do was ruin this beautiful moment.

Eventually, Gleaming ended up with her back toward Twilight, letting her younger sister be the bigger spoon between them and reveling in the way Twilight's sleepy hands wandered over her body, exploring every detail. The strap-on, which neither of them had the energy to remove, was wedged tightly – and a little wetly – against Gleaming's tail.

Twilight's wandering hand finally came to rest with a couple of her fingers dipped into Gleaming's warm, wet pussy, where they stayed. Twilight had fallen asleep with her fingers still inside ... and Gleaming didn't last much longer before drifting off herself.

Author's Note

This story is a commission for DbzOrDie. If you'd like to get a commission of your own done, go to my Patreon page and sign up! I also do commissions for one-time payments -- get the details of that on my Commissions Page.