"You know why I invited you here?" Fast gestured around the quite expansive bedroom, her smile spoke volumes for what she planned.

The purple alicorn gulped a little and looked into the room. "I… got a rough idea. Princess Fast-"

"Call me Fast, Twilight. No need to be so impersonal, I think we are well past that." The changeling bared fangs as she smiled, the very definition of steel wrapped in velvet.

Stepping forward, Twilight held her head up. "I hope you weren't hoping anything uh… well, that is…" The blush was all the hotter because Twilight was trying to imagine just what WOULD go on in here.

"Twilight, you get a choice, just one. The two options are simple ones. You stay here, you close the door behind you and I show you how wonderful a mare you are. You could leave, you close the door behind you and I find a string of lesser ponies to pass my time with." Fast spoke slowly, the tone of her voice changing to portray how horrible the second choice would be. "So, when the door closes, will you be in here?"

The alicorn gulped and looked between Fast Change and the door. Slowly her horn lit, the door held in her grip. She closed her eyes and the door at the same time.

"Good filly, 'door' is your safe word." Fast levitated a crop over, flicking it just before her eyes.

Twilight's eyes snapped open at the sound of the crop. "What… what will be your safe word, Princess Fast?"

"I thought I told you Twilight, I am not your princess, but in here I am your Mistress." Fast snapped the crop down on the covers beside her, getting a gulp from the mare by the door. "So be a good filly and get your plot over here, you were a little late and need to be punished."

Twilight took slow steps, her wings were not folded fully, she couldn't feel completely at ease, not with Fast acting quite this… dominant. "Please… Princ- Mistress Fast, go easy on me…" Her voice trembled, but not with fear. She had been late, after all, and one doesn't keep queens waiting.

Fast smiled as she watched Twilight's flanks move, each hesitant step brings the mare closer. "Up here now, on your back little filly." Fast tapped the bed beside her.

A shudder ran through Twilight at the command, more so at the way Fast referred to her. A front hoof lifted up and, before she could start to climb onto the soft bed Twilight was lifted, rising into the air in Fast's magic.

"I really must teach you to be more punctual." The queen changeling had no trouble at all flipping the alicorn onto her back, using her magic to hold her rear hooves up. "Now, I think three strokes per deed should do. You were late in showing up and slow to follow my command, so six in total." Twilight's mouth opened and Fast could see the mare was about to try and argue. "Are you fishing for nine?" The mouth snapped closed again, a blush rushing through the inverted pony's cheeks.

Twilight didn't even see when the crop drew back, but she certainly felt as it connected. "Ugh!" It struck her left rump, the initial sting easing into a dull throb. The crop came in again and hit her other side, then again, and again. Twilight bit down hard, fighting the urge to cry out, to use the safe word.

Fast was impressed, she had figured the girl would tap out right away. The sight of Twilight Sparkle, Princess of Friendship and Magic, turned on her back and receiving a good cropping, it made the changeling's blood boil. She brought the crop down, this time, so the handle struck right across Twilight's rear, knowing that the girl's rear had to be sensitive now. "One more, little filly, then you can relax. Ask me to do it, Twilight."

The words shocked the alicorn. Ask her? To be punished? A thrill ran through her, it was certainly something she had asked before, when she had done something wrong. Was it right to refuse Fast and not ask, this once? "P-Please… Princ- Mistress Fast,"

"Good filly, go on." Fast cut in, giving Twilight's belly a tickle with a hoof.

Twilight giggled at the touch. "Please, I need to be punished a little more. Can you… please, just one or two more…"

Fast looked down, Twilight was blushing so hard at the words. "My dear, I have the oddest notion you might have asked for more even if I didn't ask you to." The crop was rubbed gently against the rump that was likely cherry-red under the purple fur. The crop pulled free, twirled once in the air and came down firmly. Fast would not be one to spare anypony proper and asked-for punishment.

"Thank you!" Twilight exclaimed as it connected, her blush only increasing as the sting settled, blending into the general heat that radiated from her rump.

"That's my filly." Fast leaned down and kissed Twilight on the lips, tasting the delicious mouth that she had longed, so often, to kiss again. She didn't give up with a chaste peck, Fast drove her tongue between the alicorn's lips, delving it into the girl's mouth to taste, to feel, to explore.

Twilight closed her eyes, the soreness oddly comforting. She had done something wrong, after all, and now she had made it up. An odd delight suffused her as her mouth was invaded. She was a good filly, Fast had said so.

The kiss lasted a little longer than Fast intended it, but in the end the changeling queen drew back. "I want you, Twilight Sparkle. I want to possess you, I want to feel you, I want all of you." Fast's eyes glowed a soft green, magic pouring through every fiber of her being. "If only for this night, will you be mine?"

Twilight gazed up. She was immune to the true force of power behind those eyes, thankfully, but it didn't make her not want to be under Fast's hoof. A smile crept to her mouth. "I will be yours, Mistress Fast."

Fast felt more than lust, more than dominance. She felt love. "Good filly." Her hoof rubbed Twilight's belly some more. "I know you know a naughty spell."

Twilight blushed hotly. "I only looked at it once…"

"Once is enough, for the Princess of Magic." Fast reached the hoof lower, tracing down past Twilight's small udder, pressing gently to her mound. "You know what I want, princess, give it to your Mistress."

There was so much blush in Twilight's cheeks now she thought she would be on fire. How did Fast even know she knew that spell? How did… Her mind was racing trying to come up with the reasons, but her horn was already flashing patterns as magic flared.

Fast closed her eyes as her hoof was lifted, the hefty shaft started to grow. A matching pair of stallion balls, wrapped in a purple scrotum, swelled to match it. Fast breathed deeply, smelling the slight clue of scent that told her Twilight was now very much a stallion.

"Good filly. Or should I call you my colt now? No, you are still my filly." Fast leaned down and kissed the end of the new sheath between Twilight's legs. The kiss became more and the alicorn grunted as the warmth of a beginning erection flooded her groin.

Twilight looked down her body, her heart rate rising as she watched Fast, her Mistress, urge more and more of the strange length free of her body. "Mistress… what is… oh…" She slumped her head back as the tip of the swelling pony pole was wrapped in fang-filled lips, sucked at, teased.

Fast was quiet as she worked, her throat throbbing each time she sucked hard, but she couldn't get more than the tip of the bell-ended length into her mouth. Twilight, it seemed, was a well-endowed mare. There was a pop as she pulled free. "I need you in me, my filly." Twilight's head shot up, looking in alarm as Fast moved on the bed. They were equal size, the changeling queen and the alicorn princess, so even as Fast pulled herself over Twilight neither was dwarfed by the other.

But Fast was on top. Twilight's new Mistress.

"I could be many things for you, right now, miss Sparkle. I could be a dragon, a griffon, I could be your princess of day, or of night. But right now, my little filly, I am your Mistress." Fast spoke the words, adjusting herself a little with each pause until, arched, Fast's nethers were pressed down against that huge length. "You are not to climax until I allow it, you are not to move unless I ask it. Is this clear?"

Twilight trembled, instinct told her to buck, buck hard and spear the mare above her. But Twilight was not one to follow her instincts blindly. "Yes, Mistress." Even saying those words made Twilight ache all the more. She belonged to Fast, if only for this night. An odd ache inside, uncharacteristic for her, made her want it forever. It would be so much easier if she could just do what her Mistress wanted.

Fast rewarded her 'filly' for not only agreeing, but doing it so well. She pushed back.

Twilight's eyes bulged out, her mouth formed a perfect O as she was being engulfed in the dark black flesh of her Mistress. A soft whimper was all the sound she could make as Fast, hot, ready and already slick, took more and more of her inside, the changeling feeling so very tight and… good, right.

Fast got all the way to Twilight's medial ring and pulled back up, then pushed down more and captured that mid-point, rather than pull back up again she pushed on, not stopping until her rump was planted in Twilight's lap. The position she had the alicorn in had several bonuses, being in nearly complete control was the best, but the other was that with this angle, more of the 'stallion' could be inside her.

Head flopped sideways, Twilight was fighting urges, strong ones. Her body wanted to push her Mistress over, to ride her like a stallion should. She wanted to pump and hump, to cream and plant foals in her owner. But her mind was strong, it bound her muscles, it bound her entire being into doing just what Fast told her. Above her, her Mistress rocked forward, then back, repeating the motion again, then again, and pretty soon Twilight's soft whimpers of need were washed out by the sound of sex.

Fast had had big lovers before, she had had strong ones. But this was something very special. Bucking, pumping, she was in complete control as she let her body ride Twilight's huge stallion-shaft. Pretty soon the combination of pleasure and the dominance aspect started to really catch up for the changeling and she was panting.

"Mistress?" Twilight managed to get the word out, it was a fight. Everything was a fight now, however, but none more-so than holding herself back. It was by force of will that the alicorn hadn't lost all control but that will was a strong one.

The word tipped poor Fast, hearing her new toy call her mistress, even in the heat of their first play together, it made her head suddenly start to flood with endorphin. A flood of pleasure started in every cell that contacted that huge pony pole. The wave of pleasure that burnt down her nerves had her clench her muscles and she managed to whimper, "cum, Slow," a moment before her voice was stolen.

The fire of green that swelled over the mare under her was slow, it didn't rush, but when it was gone a changeling stallion was on their back, the features turning to the silliest look Fast had ever seen a lover give, and she had seen a few.

Slow Perfection looked up at his queen as his body started to let go, trembling as not just a climax took him, but a whole new kind of change. He trembled as his balls unleashed, his shaft pulsing and swelling as it was soon gushing the hot changeling seed into the queen above him. His stature didn't shrink much, but a new heat burned in his groin as magic, focused and pure, poured from him into Fast.

This tipped Fast from the trailing edge of one orgasm into another. She tumbled forward and pressed her lips to Slow's. The kiss was returned as she held her lover tight. Her mind was coming down from her repeated release, the surety that she would soon be carrying eggs seeming to come from nowhere.

Slow saw the tears roll down Fast's snout; he kissed them away. "My queen, and you will always be that, please don't cry. You cannot have her now, but she didn't say never. Until then, you can have me." He smiled up at her, gazed into his queen's eyes as she opened them.

"Thank you, Slow… you are bigger?" Fast just realized that not only was the changeling physically bigger than he had been, but that his other 'size boost' was maintained too.

"I am your breeder now, your magic made me so."

Fast wasn't sure why, but the tears kept coming, even as her legs joined Slow's in holding them close together.

Author's Notes:

Oh glob, puns, I am so sorry for the title.

Not sorry for the twist, #shyamalanstyle