Author's Note
Some toy play and spanking are ahead!
The Summons
It had been at least an hour after the invitations had been sent out. Princess Celestia and Princess Twilight were enjoying a peaceful moment of togetherness in the privacy of the solar princess' private quarters. As a pony might suspect, it was pretty conventional and the color decor was of various shades of yellow that one might associate with the rising and setting sun.
"So, who do you think will be the first to question if we're out of our little pony minds," Twilight jested as she relaxed on the extremely thick cuddly blankets that covered Princess Celestia's large bed. Occasionally she'd wince, eyes squeezing shut as a spur of pain shot through her hindquarters where Celestia had just finished giving her a good sound spanking with the bottom of her royal hoof. Now she was just being teased as the sun princess kneaded her hindquarters, smearing a clear gel that brought a wonderful cooling relief to her fiery derriere.
Celestia simply laughed, sounding as carefree and hopeful as she always did. "Luna," she answered simply, "cause I am sure the idea of any pony laying a hoof or otherwise on her backside would be equal to heresy."
Twilight chewed on that for a moment, letting out a yelp as Celestia's hoof suddenly and surprisingly struck her backside. She didn't complain though, she knew better. The onyx leather collar around her neck with a trinket resembling Celestia's cutie mark was testament to Twilight's acceptance of her role in their relationship. A relationship that had so far been kept discreetly between them. That was to change with this meeting, tactfully under the guise of establishing a means for Equestrian royalty to be punished when it was considered necessary.
"Mistress, am I to keep my collar visible during the the meeting," Twilight asked, even if she surely knew the answer she'd get. Her eyes shot open and she gasped sharply as the larger alabaster alicorn's teeth grasped her by the nape. By now, she had trained her body to be obedient and never instinctively respond to Celestia's sometimes questionable actions with defensive countermeasures. Soon enough, the painful tension released as Celestia's teeth relaxed and moved away.
"Oh yes, but you'll only explain if asked. However, I think the demonstration will be enough to establish the facts as they stand," she lipped. She now cradled the lavender alicorn in her forelegs, muzzle pushing through Twilight's mane as she motherly licked at where she had just bit her.
Twilight's ears perked up, "Demonstration," she said with an inquiring tone. Immediately the idea set into motion a myriad of ideas that played through her head. She almost felt a bit of pity for her rump as it would no doubt be on the receiving end of whatever her Mistress had planned.
"Twilight, bite the pillow for a moment."
Celestia's voice suddenly took on a sense of seriousness. A tone that Twilight Sparkle was all too familiar with and never hesitated to follow any order given in it. She grabbed the nearest pillow with her forehooves and dug her teeth into it, suspecting that Celestia was indulge in something of considerably immense pain. She let out a muffled whimper as she felt the conical tip of an all too familiar toy push against her rumphole. What little resistance her orifice offered was meager as her puckered hole almost eagerly swallowed the plug . Only the flat thin base remained, the dip making sure it stayed in place. There was no mistaking that cutie mark emblazoned on the bottom, it was Princess Celestia's.
"Make it bigger please, Mistress," Twilight begged. She wanted that sense of fullness, to feel her orifice stretched so far that it tipped over her comfort zone. She could always recall the first time her Mistress used this particular toy. She was gentle, kind and there was at least a quarter of a bottle of lubrication used by the end of it. Now though... now she took it dry, Twilight reveled in the pain that came with her dry hole being forced to stretch open and accept the plug.
"Bigger," Celestia mouthed as her golden magic reached out and grasped the toy. It was to much delight that she watched as she steadily increased the size of the toy. The sight of her pet's backside yielding orifice stirred her loins, enough so that she would've reached a hoof down to tend her growing needs if she wasn't so infatuated with the scene playing out in front of her. By now, her pet's orifice was so far stretched out that she swore a hoof could slip inside with little effort.
Twilight whimpered, not in pleasure or discomfort, but in pain. Immediately Celestia's magic fell away and the larger mare leaned her head down to Twilight's in concern. "Are you all right, Twilight," Celestia asked, the air of dominance giving way to an instinctive motherly concern for the safety of her friend.
"I'm... fine," Twilight muttered as she gave a push against the toy lodged in her rump. This was definitely out of her comfort zone. She was breathing heavily, trying best to ignore the pain and just relax.
Celestia, by all accounts, wasn't exactly convinced, but she feigned a smile and gave Twilight an affectionate lick across the cheek. "I'm going to shrink it down a little," she said before pulling away. Her magic seized the toy, her channeled magic shrinking it down till she heard Twilight give just the softest little sigh of relief.
"Thank you, Mistress," Twilight smiled and closed her eyes as the pain slipped away and was replaced by the sense of fullness she enjoyed so much-loved. Though the peace in mind was short lived as the bottom of her Mistress' hoof gave her still raised rear a few sharp swats that made Twilight moan out uncontrollably. It was a short ten licks, but by the stingy fire rekindled on her backside, they must have been her hardest. "Thank you again, Mistress," Twilight reached back and rubbed her used and abused rear.
"Any time my pet, but now we need to attend to other matters at hoof. Cadence and Shining Armor have arrived and my sister will be waking up soon," Celestia slid off the bed, turned then offered Twilight a smile. "Come, Twilight, lets not keep our guests waiting any longer than we have to," she then sauntered intentionally toward the door, giving Twilight plenty of time to admire that rear which had since widened by her penchant for cake.
Twilight did stare as Celestia expected, having no shame in the fact she was ogling the ass of somepony who was not only a mentor, but in some ways a mother and, as of the last few months, her Mistress. "Right behind you, princess," Twilight pulled herself off the bed, wincing in pain as she felt her anus grasp tightly around the plug as well as her derriere throbbing in a bit of pain. All the while, her eyes never left her Mistress' flanks as they made their way to the meeting room. Even now, she could smell the scent of arousal. Those lovely white folds were moist and winking involuntarily, exposing her glistening fat pink clitoris periodically.
"You'll be taking care of that after the meeting, of course," Princess Celestia murmured as they stepped into the room where Luna, Cadence and Shining Armor were patiently waiting.
Twilight blushed, the princess knowing her all too well made it impossible to ever hide her intentions even if she never spoke them. "Of course, Mistress," she said rather loudly. Shining Armor and Cadence were absolutely shocked, but Luna merely rolled her eyes.
"I should be surprised, but then I suspected as much when Twilight Sparkle kept showing up at the castle at such queer times," Luna was the first to break the awkward silence.