A Mare and Her Mirror: Applied Narcissism and Other Erotic Oddities

“In conclusion, while Newton’s laws of motion are inappropriate for use in certain extremely uncommon circumstances, they provide a reliable framework for explaining a wide variety of nonmagical phenomena involving any body which can be considered as a particle.”

Twilight Sparkle struggled halfheartedly against the ropes that tied her limbs to the corners of her bed. She had long since given up hope of escape, but still, the effort had to be made. The personal protege of Princess Celestia herself would not--no, could not--simply lie there belly-down and submit to the treatment she was being subjected to. It was humiliating. It was degrading. It was the nightmare scenario that had haunted her all throughout her fillyhood and well into her young adult years.

Remedial tutoring.

“Miss Sparkle, are you paying attention?”

Twilight strained to turn her head. Out of the corner of her eye, she could just make out the purple coat of her tormentor in the dim light of a single lavender candle. Her breath caught in her throat slightly as she saw the candlelight reflecting in deep purple eyes. This was the only pony who would ever truly understand. The only pony who loved knowledge and learning the same way she did. And she was the only pony who would ever have to know about tonight. All thanks to a spell she had originally invented just to let her attend a party and watch the stars at the same time.

The edges of Twilight’s lips curled up into the beginnings of a smile, then she quickly turned the expression into a grimace as the other unicorn caught her eye. She averted her gaze and started to struggle against the ropes again. It wouldn’t do to break character now. Roleplaying was a very important part of bondage. The book had said so.

The only warning she had was the slight pulling sensation near the base of her horn that she always felt when magic was being used nearby. A flat surface struck her rump with stinging force, making her gasp in surprise and sending a sharp slap echoing through the otherwise silent room. Her tail, traitor that it was, had risen of its own accord at some point during the lecture, and provided no defense against the blow.

“Apparently not,” her mirror image murmured huskily. “It appears that we’ll have to try a more hooves-on approach to your education.”

Twilight heard the sound of a book closing, and she whimpered softly. The other pony let out a satisfied hum, apparently pleased with the sound, and a hoof brushed through Twilight’s mane and down her spine.

“Now, my little pony,” the mare beside her said, “let’s see if you’ve been paying attention. You have been paying attention, haven’t you?”

Twilight swallowed hard and nodded, her ears lifting nervously.

Her twin’s voice had a dangerous edge to it when she spoke again, her warm breath tickling at Twilight’s ear as she leaned close. “I said,” she murmured, “have you been paying attention?” The last word was punctuated by the tug of magic, and the object slapped into her exposed rump again. Twilight yelped in surprise.

“Yes ma’am!” she squeaked. Another slap prompted her to elaborate. “Yes ma’am I’ve been paying attention!” Her backside was starting to sting from the abuse; whatever the other unicorn was using, it was heavy, and quite hard. Actually, judging by its weight and the amount of magic used to swing it, she realized she could narrow it down to one of three books in her library. And the only one of those she had in her room was...

“Memoirs of a Metaphysicist, by Starswirl the Bearded,” purred her twin, as if reading her thoughts. “A personal favorite of ours, I believe...” Twilight whimpered an acknowledgement, then--Slap! She gasped sharply as another strike from the weighty tome sent a shudder up her spine. “But,” her twin murmured smugly, “we’re getting off topic.”

Twilight felt the other unicorn lay down beside her, leaning into her side. She looked over to see a smirk on the purple mare’s face in the dim candlelight, and the glow of telekinesis still around her horn. That smirk widened as she caught her looking, and the glow brightened briefly. Slap! Twilight yelped and jerked her gaze back toward the headboard.

“Eyes forward, Sparkle,” her twin reprimanded her. Hot breath tickled her ear again, and she flicked it nervously. “Now, recite Newton’s first law of motion...”

This, at least, was more than familiar territory. Confidently, Twilight closed her eyes and raised her head slightly. “Every body,” she began, “persists in its state of being at rest or of--” Her recital faltered at a sharp pain at the tip of her ear. Teeth! The other mare had nipped her! Knowing that stopping would only make her situation worse, Twilight pressed on. “...a-at rest or of moving uniformly--” She squeaked as she was bitten again. “...of moving uniformly straight forward!” she finished in a rush.

“Except...?” prompted her twin. Twilight heard a distinctive click underneath her bed, and her eyes widened.

She... she was opening that box. The one marked “Study Aids”; a label boring enough to keep Spike from investigating, yet vague enough that its contents could technically be considered properly categorized. The one with all the...

Her mind froze up for a moment, and she began to struggle against the ropes binding her. The stinging impact of Memoirs of a Metaphysicist against her rump brought her quickly back to reality. She noticed that the warmth of the other unicorn against her side was gone now.

“Except,” she recited, biting her lip, “insofar as it is compelled to change its state by--” All thought fled her mind as a warm body pressed her down against the bed, a soft coat pinning her raised tail to her back, and firm thighs closing around her flanks. And then something settled against her rump. Something rubbery, with just a slight give to it. Something long, and thick, and oh Celestia it was rubbing up against her in just the right place right now.

“...by force impressed,“ her twin finished for her in a throaty murmur. “But of course, we can only apply these laws to a body,” and here, the way she emphasized body sent a shiver down Twilight’s spine, “which can be modeled as a particle. Can we model your body as a particle, Miss Sparkle?”

“N-no, of course not,” Twilight said, shaking her head and trying to recover the thread of the conversation. “The equine body is far too complex a system--” Oh by Starswirl’s beard! Now the tip was pressing its way between her folds... “--to be represented by such a simple--” ...rubbing and slipping against her flesh, becoming covered in her wetness... “--such a simple--”

Suddenly, unexpectedly... fullness. The rubbery shaft slammed into her, its passage eased by her wetness... and her twin’s. The thing had been worked against them from hilt to tip before it was thrust into her, and it was slick, and warm, and the air was filled with a moan that it took her a moment to realize was her own. This was nothing like her “private study sessions”. The element of surprise, the surrender of control, the feeling of being... of just being with somepony else...

“I think, Twilight Sparkle,” her twin murmured, interrupting her thoughts, “that you can be modeled as a particle.”

“But I’m not--” Twilight stammered. The mare pinning her to the bed nipped her ear again. “A pony can’t be--” she tried again.

“You’re a particle, Twilight Sparkle,” her twin said with just the hint of a growl. Twilight tried to protest, but moaned instead as the thickness that filled her was pulled almost all the way out, the hot underside of the mare behind her grinding against her back as she moved with it. “You’re a particle,” the mare repeated, “and I will model you like a particle.” The feeling of magic was a constant now, as her tormentor used a telekinetic grip to synchronize the movement of the shaft with her own motions.

Any protest Twilight might have voiced was driven from her lips as the thighs around her flanks tightened, and the emptiness inside her was again filled with a swift forward thrust. “Yes!!” she squealed. “Yes, I’m a particle!”

“A very, very bad particle,” her twin’s voice agreed with her from beside her ear. “Now tell me about Newton’s second law...”

Again, the clarity of a question she could answer flooded Twilight’s awareness, sweeping away the distracting fog of passion. She latched onto the question like a lifeline. “The second law,” she recited, with as much scholarly aplomb as a mare with several inches of silicone rubber buried in her could be reasonably expected to muster, “states that the alteration of a body’s motion is proportional to the force impressed upon it, and--” she gritted her teeth as the “study aid” was thrust into her again. “And that the direction of the resulting motion is... oh sweet mother of Luna... is a compound of its original direction... and the direction of the newly-applied force...”

“Very good, Twilight. So if we wanted to change the direction of your motion, all we would have to do is...?”

Something about the way she asked it made Twilight suddenly wary, and she tensed under her twin. She gnawed absently on her lip, an instinctive sign of reflection, as she considered the question very carefully. “You would... apply a second force?” she ventured. Then realization hit her, and her ears pinned flat back against her head. “Oh hay no! You are not--”

She was. Before Twilight could protest, another item from her stash had been pressed against her just above the first, right between the cheeks of her still-sore rump. Caught by surprised, she bucked violently, almost throwing her twin. The pressure released for a moment, but then it reasserted itself as the mare behind her regained her balance. Twilight strained against her bonds, trying to squirm away from the object. It was warm and wet, already soaked with the juices of the other mare, and in the end, her squirming served only to work it against her, which at this point she was about ready to admit just might have been a little bit purposeful on her part.

Then her twin withdrew the larger shaft from her and she arched back instinctively, trying to reclaim the warm fullness that had escaped her. The motion drove the slick body of the smaller toy up under her tail, and ridges battered themselves against the tight ring of her flesh as it entered her. Not a second later, eight more inches of pleasure shot up her spine as the other shaft thrust in to fill the emptiness she had felt, and she lost all pretenses of resistance.

“Exactly,” breathed her twin from behind her. “And do you like being acted on by two forces at once? Are you a bad little particle?” She started to move against Twilight, their coats slick with sweat and slipping against each other, both shafts thrusting with each of her slow, methodical motions.

“Y-yes,” Twilight panted. Her mind was a mess of feelings, all of them good. The ridged length of one shaft battered her flesh relentlessly, the merciless girth of the other stretched her in a way that was just indescribable, and she could feel her twin leaning down against her back, the full length of their bodies pressing together.

“I didn’t hear you,” the other mare murmured, nipping again at her ear. “Are you a bad particle?” The question was punctuated with a powerful forward thrust, and pleasure shot through Twilight’s body from horn to hoof.

“Yes!!” she squealed. “Yes, I’m a bad particle! A very bad particle! Apply more force to me!”

That was all the prompting her twin needed. Her thrusting grew faster, the pauses between thrusts disappearing as she started to nibble on Twilight’s ear. Twilight bucked her body back, letting out soft moans and whimpers as she settled into the rhythm and allowed the waves of pleasure to wash over her. It felt so amazingly, deliciously good, and slowly, she surrendered herself to...

No. Not surrendered. Twilight Sparkle might concede a temporary defeat, but she never surrendered. Her horn lit up, but her twin failed to notice, caught up as she was in the excitement of the moment and her apparent fascination with chewing on Twilight’s ear. It was technically cheating for a unicorn to use her magic during bondage, but... well, all was fair in love and war, right? It said so in a book. And, anyway, the lesson wasn’t over yet.

“You f-forgot... the third law,” Twilight managed through her soft panting. She fumbled through the remaining items in her collection until she found what she was looking for.

“Mmm,” her twin agreed distractedly. She was panting now too, excited by the intimacy of the moment and the feeling of their coats rubbing together. “Why don’t you recite that for me now, then?”

“The third law,” Twilight said, with a telltale trace of smugness in her voice that her twin entirely failed to pick up on in time, “is that for every action...” The silicone shaft of another toy was lifted up by her telekinesis, and positioned itself behind the unsuspecting mare. “...there is an equal and opposite... reaction!”

She felt her twin stiffen against her as the length of it slid home, and was rewarded by a loud, throaty moan. The other mare’s rhythm faltered, but Twilight didn’t let up, matching her with thrusts of her own. She soon felt her partner reciprocate again, and she ground herself back against the twin shafts as they pumped inside her. The heat was overwhelming, and more soft whimpers and moans started to join her own.

The candle on the bedside table burned low, and then finally flickered out as the quiet sounds of their passion filled the room. At some point, adrift in the moment, in the ebb and flow of the tides of her pleasure, Twilight stopped fighting against her double, and their rhythms synchronized into a single motion. It was no longer about teacher and student, or about a particle and the forces acting on it. It was about two deformable bodies, applying equal and opposite forces against each other, mutually balanced inside a single inertial reference frame. It was magic. It was science. It was harmony. And she loved every panting, sweating, grinding and thrusting moment of it.

But all too soon, a growing tightness in her belly signaled that it was coming to an end. She bucked herself back against her partner’s thrusts with a quickly rising need, feeling the other mare start to tense against her as she felt the same urgency. The rhythm changed then, speeding up rapidly, as they both sought to drive each other toward their common goal.

Her twin climaxed first. She could feel the body against hers shudder, and heard the loud, throaty moan as the pleasure of orgasm overtook her lover. A powerful, desperate buck from the other mare drove the two magically-held shafts into her again, and she responded in kind, rutting hard against the objects that penetrated her. Her partner continued to drive into her even as her own climax ebbed, determined that Twilight should reach that same peak.

And then it hit. Pleasure, white hot and radiant with all the fire and glory of Celestia’s sun, shot through her body, driving all thought before it. The world around her vanished for a moment, or perhaps for an hour, and she just floated in the splendour of its warmth. Then reality returned around her and she heard--or perhaps remembered hearing it just a moment ago--a long, shuddering scream of ecstasy. Her own. She realized, after a moment of panting for breath, that her eyes were shut tightly, and she opened them.

The two shafts were pulled from her, sending one last shiver through her body. The ropes holding her forelegs were loosened then removed, freeing her to sit up a bit. Then she felt the weight leave her back as her twin slid off her, laying on her side next to her. In the thin light of the stars that filtered in through her blinds, she could just make out a smile on the other mare’s face as she leaned in to...

“Th-thaumaturgy.”

Her twin halted at the sound of their chosen safeword, a confused mix of barely-discernible emotions flitting across her face. She finally settled on acceptance, her ears drooping a bit, and nodded silently.

“No kissing,” Twilight murmured. “This isn’t... that was just...”

“...just masturbation,” her twin finished quietly, her eyes downcast.

“Yeah...” Twilight agreed. That was all it was. It was all it could be. She was technically touching herself. So why did it feel so wrong to say it that way? Tentatively, she reached a hoof out to touch the other mare’s muzzle.

She was interrupted by a knock at the door, and both unicorns jumped in alarm, horns lighting up as they scrambled to simultaneously pull the covers over themselves, untie the rest of the ropes, and shove the box of “study aids” back under the bed.

“Are you two okay in there?” the sleepy voice of their number one assistant called through the door. “Do I need to get Princess Celestia?”

“N-no!” both unicorns yelped in unison. “I mean yes! I mean we’re okay!”

The two looked at each other sheepishly through the near-darkness, then Twilight finished, “We we just... studying! Studying, uh, physics!”

“...alright.” They could almost hear Spike shrug and turn away from the door. “Just try to keep it down, huh? Some of us are trying to sleep here.” The tapping of clawed footsteps walking away was followed shortly by the thumps of a baby-dragon-sized bed being dragged down a set of stairs, and the near-inaudible grumble of, “...if I’d known physics was that exciting, I would’ve paid more attention in class.” And then silence.

“We should probably apologize to him in the morning,” Twilight said finally.

“Definitely,” her twin agreed. The room lit with the glow of magic as they finished untying the ropes, then they pulled the covers more snugly over themselves. Twilight smiled in the darkness as they pressed close in the small shared bed, the comforting warmth of the other mare seeping into her from everywhere their bodies touched. She nuzzled happily against the warm neck in front of her.

“But... I really... liked that,” she ventured, almost shyly.

“I really liked that too,” the other mare murmured back. But as Twilight drifted off toward Luna’s realm of dreams, she imagined to herself that she’d heard another word, haunting and beautiful and hovering just at the edge of her uncertainty and doubt.

Love.