"I've had just about enough of this."
Rarity looked down; The Mule knew its place, and addressed her from the floor, prostrate before her. The fact that it seemed to have forgotten the proper manner of addressing a lady irked her, but she found the mercy necessary to overlook the slight; Rarity had developed a bit of a fondness for The Mule, truth be told, despite its rough looks and lack of grace. She supposed she just had a generous heart, to be able to love such a miserable wretch as this. The purple-maned unicorn sighed. She had been relaxing, but she supposed whatever was bothering her pet should be addressed first; business before pleasure, after all. "Why, what ever do you mean, my dear Mule?"
The Mule paused in thought before replying, "...Well, I just don't think that this is the normal way lovers act. I mean, I don't have much experience with pony courtship, but I've never read about anything like this."
Rarity nodded, feigning concern, "Well, Mule darling, I suppose it's not normal, per se, but normal is for the common sort. Rarity has always demanded the exceptional. You simply haven't read the correct books. Fear not, my little Mule, you can borrow them. I'm sure you'll enjoy them quite as much as I do." Rarity was glad that, for all its unsophistication, the Mule could at least read well.
The Mule seemed only partially convinced. It spoke again, "Well, okay, I guess. But... um... about when we get... intimate. Could you stop calling me a 'dirty disgusting Mule' and raving about how much I sicken you? It sort of hurts my feelings a bit, sometimes. And I'm not sure why you want me to bray when you spank me, or why you spank me so often, for that matter, but it's really weird."
Rarity tilted her head. The Mule had never objected to that sort of thing before; The Mule seemed to enjoy it all as much as she did. "But darling, it adds so much spice. Surely you don't want lovemaking to get boring, do you? Besides, we both know what being spoken down to does to you, and that certainly helps things along, and a little discipline is such delightful foreplay. You certainly didn't seem to mind it last night." The Mule blushed at the reminder of its usual tastes.
"Alright, I guess that makes sense. But could you at least stop calling me Mule? It's a bit offensive. And possibly racist, I'm not really sure. You used to call me by my real name." The Mule looked up at Rarity pleadingly.
The dressmaker clicked her tongue in annoyance, "Fine. I will occasionally call you by your name. But you must remember to address me properly from now on. In any case, I grow weary of this conversation," Rarity extended a hoof out toward her Mule, "You may now lick my hoof clean."
The mule responded in a tone of resignation, "Yes, Miss Rarity."
***
That hadn't gone how she had wanted at all. Twilight Sparkle sighed to herself as her tongue worked; she supposed that she'd just have to get used to being called Mule.
There was a collar around Twilight Sparkle's neck. The elegant loop of silver was uncomfortable, but the unicorn had since grown more than accustomed to the constriction; It had become a reassuring pressure. The soft metal was sometimes painful, often restrictive, and always beautiful... just like the mare who owned her, body and soul. A chain of tiny, delicate links connected the shining loop to an elegant clip, which currently adorned the immaculately-styled tail of her mistress, Rarity.
The pair was on a walk through Ponyville, and Rarity seemed to be quite enjoying herself, humming as she strolled serenely through the town square. Twilight could not help but keep pace just behind her mistress; the chain connecting them was only as long as her leg, and she could not allow it to go taut; the collared mare knew better than to break one of the delicate links, or worse: pull the clip enough to displace a hair in the white unicorn's tail.
Twilight was far less pleased with the situation than her mistress seemed to be. She chewed nervously on the riding crop that Rarity had instructed her to hold. The bookish mare tried to keep her gaze focused on the white flanks in front of her, but it was a struggle. All too often, she'd glance to one side or the other; when she saw a stallion, her eyes would linger, sizing him up with a fevered desire.
The mare gave her head a small shake as she realized that she'd been doing exactly that. The purple unicorn's eyes had been running longingly over some blue stallion's legs, waiting for him to turn enough that she could get a glimpse of his sheath. He had probably been looking at her too; all the ponies seemed to be. Twilight was sure that Rarity had wanted it that way from the moment they stepped out the door, and her mistress always got what she wanted.
And so Twilight Sparkle was walking through the ponyville town square, levitating her own tail to present herself. That had been Rarity's instruction, and disobedience was unthinkable.
The cool air of the spring morning felt almost painful against the heat between her haunches. Whenever the librarian thought of all the eyes focused there, all the stallions watching her, desiring her, willing to take her, she was almost overcome by the heady rush of her own arousal. Twilight knew that she was in heat. She could smell her own scent on the wind; it was probably as obvious as a neon sign to the male residents of ponyville. The mare snickered despite herself as she mused about what such a sign might say.
Twilight's Business is Open for Business.
The unicorn suppressed her mirth and tried to focus on her mistress. The swaying of those flawless white flanks did little to curb her arousal, but at least it was a less maddening sort of desire, one with which she had far more experience. Twilight wondered what she'd done to deserve being paraded around Ponyville in such a condition. It could have been just simple random cruelty; that would not have been a surprise, coming from her mistress. She could see no other obvious reason.
The librarian wondered what would happen after the walk. She frowned as she absentmindedly worked her tongue against the crop in her mouth. No doubt the implement would see use; the day was young, and Rarity always had big plans when she forced Twilight to close the library for the day.
Rarity greeted ponies with customary pleasant words, as though the stallions (And many of the mares) they passed weren't sizing up the purple unicorn for a hard rut. Twilight sighed. At least the dressmaker was enjoying her humiliation; even her mistress's rear end looked pleased with itself.
***
The contraption hanging from the ceiling was a new addition to the room. Twilight's home away from home in the basement of Carousel Boutique had always been a sea of whites. From the piles of cushions that Rarity used for lounging to the tile floor that was the most comfortable surface the purple unicorn was allowed to rest on, everything was uniformly colorless. Every bit of the chamber had glowed in candlelight and shone in the harsh illumination of magic, and the new fixture seemed starkly out of place. A black metal pulley was secured to the roof in the middle of the room, and a cascade of light brown straps and brass buckles hung limply from it. The librarian could see no logic to the tangle.
The door behind Twilight closed with a bang, as it always did. It was a delightfully forbidding sound, and the mare felt a shiver of desire run up her spine, triggered by long association between the noise and things to come. The arousal she'd felt on their walk did not diminish away from the stallions that caused it, and her scent quickly filled the small room.
Rarity unclipped the chain from her tail, leaving it to dangle between Twilight's forelegs. The librarian merely stood silently, waiting, keeping her tail levitated as the white unicorn walked slowly around her. The librarian could feel her mistress's gaze, traveling along her body.
When the dressmaker had made a full circuit, she came to a stop in front of her pet and nodded to herself, apparently satisfied. "Open, Mule," Rarity said, using her customary form of address for Twilight Sparkle.
The purple mare opened her mouth, careful not to let the crop she'd been holding fall out. Her mistress waited a few moments before wrapping the implement in a sheathe of levitation magic and lifting it out of its resting place. Rarity ran the crop along Twilight's body, trailing the flexible tip lightly across the librarian's cutie mark before returning to close the mare's jaw with a bit of pressure from the rigid core of the tool.
With an amused smirk upon her flawless face, Rarity spoke, "So, my little Mule, did you enjoy our walk this morning?" She teased her pet with the end of the crop, brushing lightly against the sensitive flesh of the other mare's neck.
Twilight fell to her knees, prostrating herself before the other mare. The floating scourge followed without hesitation. "No, Mistress," she said, a nervous quaver in her voice.
"That's such a shame," the dressmaker said without a hint of sincerity, "it's a nice day outside, darling. Our walks are normally so pleasant. What was the wrong with today?"
The purple unicorn struggled to answer through the haze of her arousal as Rarity's levitated toy pressed against her flank. "The stallions," she finally managed. The mare let out an involuntary whine as her mistress removed the maddening touch of the crop. She squirmed in place, trying subconsciously to find some pressure, some sensation to satisfy the exquisite ache between her haunches.
Rarity turned away from Twilight, and a hard note entered her voice. "Do you know why you feel this way, Mule?"
The submissive mare's ears folded back. She murmured, "...I'm in heat."
Twilight cried out as the light whistle of Rarity's crop swinging through the air was followed by a stinging blow across her flank, just above her sensitive cutie mark. Her mistress spoke with practiced nonchalance, "What was that, my dear Mule? I believe I've told you before to speak clearly when addressing me."
"I'm in heat!" the unicorn practically shouted. The crop returned to its previous light teasing. For a moment, she admired the magical control the other mare showed; accurate telekinesis without looking was a feat few accomplished. Of course, Rarity was nothing if not precise. Measured. Deliberate.
The dressmaker nodded, then looked over her shoulder at the other mare. "Of course darling. You're quite obvious about it. The real question is," her eye narrowed, "why have I never seen you in heat before?"
"Um...," Twilight stalled. She felt the crop's impact as a searing line across her haunches. Neither pony commented on it; the unicorn knew what she'd done. "Because I've never been in heat before," the mare finished in a rush.
Rarity sighed. "I figured as much." She paused, then continued in a lower tone, "Mule, do you by any chance know how you managed to avoid estrus for so long?"
"I didn't ever get enough sunlight."
The white unicorn whirled to face the other mare, who quailed at the sudden rage on her mistress's face. "You knew!?" The dressmaker yelled, and Twilight felt another stinging pain on her flank. The mare lost herself in delicious agony as Rarity ranted, punctuating sentences with blows to Twilight's hindquarters, the crop whistling furiously. "Don't you know how unhealthy that is? You've been of legal age for years. You got your cutie mark years before that! In all that time, you've never bothered to go outside, or even read at the window during the spring? You stupid Mule! You should have known far better than that. If anypony should realize how important sunlight is to the proper hormone balance and emotional health of a young mare, it ought to be the personal student of Princess Celestia! How you managed to avoid getting enough daylight to ever begin your estrus cycle while studying under the goddess that raises the sun is beyond me! If I hadn't ordered you to stay outside during the day these past few weeks, you would have gone on blissfully trying to evade your biology forever, wouldn't you have, Mule!?"
Rarity sighed and shook her head, and the blows stopped. Her words continued, though the fury was gone, "You truly don't know how to take care of yourself, do you darling? Oh well; mules need to be trained, and you are no exception. Here is what is going to happen, Mule. You are going to spend as much of your time as possible in outdoors in the spring and summer. You are going to have a regular estrus cycle, including heat. You're going to do it because it's healthy and normal. Do you understand, Mule?"
"Yes mistress Rarity," Twilight replied, still nearly lost in the sharp pain that the crop had left in its wake.
The white unicorn circled around the other mare and stopped by the door. "Now, Mule, I know you well. I figured that you'd be like me; during heat, your desires turn to stallions. Judging from where your eyes were for the vast majority of our little walk this morning, I was correct. There's no shame in that darling, we just happen to not be among the lucky mares that desire only their own gender during estrus. Alas. Still, no use lamenting things we could not choose. We are all slaves to biology," Rarity said. "But remember," she continued, her face twisting into a wicked grin, "first and foremost, you're a slave to me." The crop's impact on Twilight's haunches drove home the point.
The dressmaker continued, "In any case, I find it useful to keep a stallion or two around, for when I, too, am overtaken by such base urges. It's nigh on impossible to clear one's mind without indulging them. That's why I set up a little surprise for you. I'm quite generous enough to share. You'll enjoy the vulgar exercise as much as the next mule, no doubt." Rarity opened the door with magic, just wide enough to stick her head out and shout down the hallway, "Okay Big Mac, darling, we're ready for you!"
Twilight's eyes widened as she realized what was happening. She didn't know whether she was more shocked by the situation, or by how much she was looking forward to the rest of the day.
Rarity turned to the other mare and smiled as she held the door open. "Don't worry, my little Mule," she said, "I know you've never been with a stallion before, but you're in good hooves. I'll show you how it's done, dear."
"Thank you, mistress Rarity."