Futanitiation

"Wait, what?" Twilight asked, puzzled. She had already finished growing her new cock and balls, and she thought she was done already, but that, apparently, was not true.

"Not yet, Twilight," Luna replied, "In order to complete this process fully, you must make sure your new stallionhood is working properly."

"And...how do I do that? Do I just pleasure myself right here in front of you?"

"Not quite, my dear," Celestia replied.

"Let me explain, Twilight," Cadance said, "You see, when this happened to me, I had to release my own seed inside Celestia. You're going to have to do the same thing, but since there's three of us, you'll have to do it three times."

Twilight once again stood motionless in front of the other princesses. Was she really going to have to engage in intercourse with all of them? True, she had basically just done that, but this was different. Instead of having a part of them inside of her, she would have to put herself inside of them. Still, while her common sense seemed to be holding the world's largest protest in her brain, her scientific curiosity made her want to feel the pleasure that came from having a penis.

Smiling weakly, Twilight asked, "So...who am I starting with?"

"Whoever you choose, Twilight," Celestia replied.

Twilight then thought about her options for a few seconds. "Cadance," she said, looking over at her sister-in-law, "I think I'll start with you."

"With me? Again?" Cadance asked.

"Sure! Why not?"

Without saying another word, Cadance levitated a king-sized mattress from another corner of the room, set it in front of Twilight, and then laid down on her back. She spread her legs, and Twilight realized that her sister-in-law had already become aroused, her dick at full mast and her pussy already soaked. "Did...did she get turned on by what I did with Luna and Celestia?" she thought to herself. She immediately brushed it away and climbed over Cadance. "Are you ready?" the purple alicorn asked.

"I'm ready whenever you are, Twilight," Cadance responded.

Before Twilight got herself fully into position, she took another glance at Cadance's marehood. Technically, she had already tasted her juices, but at the same time, she hadn't. She reached a forehoof down to the pink alicorn's nether regions and asked, "D-do you mind if I...?"

"Go ahead," Cadance replied.

Twilight felt extremely awkward asking such a question to her sister-in-law, but at the same time, in her curious and aroused state, she wanted to know how she tasted. Twilight lowered her hoof until it reached the bottom of Cadance's outer lips, making the pink mare shiver in arousal. The purple alicorn gave a slow, upward stroke until she reached the clitoris, then pulled away. She then brought her hoof up to her muzzle and gave it a lick. It was a slightly bitter taste, but other than that, it wasn't half bad.

Twilight licked the rest of Cadance's essence off her hoof before returning her focus to the task at hoof. She lowered her backside until the tip of her new stallionhood was aligned with Cadance's vagina. After looking up and getting one last go-ahead nod from her sister-in-law, Twilight pressed forward, sinking the tip of her cock into Cadance. Both mares moaned at the feeling, Twilight being the louder one as this was her first time experiencing such a sensation. Only minutes earlier had she clamped down on something inside of her, but never in her life had she had something clamp down on part of her own body like this. Nowhere in her lust-addled brain could she find the words to describe how she felt at that moment.

The young alicorn continued, pushing the rest of her cock into Cadance until she was fully hilted inside her sister-in-law. The feeling was so intense that Twilight's hind legs gave out almost instantly, and she collapsed onto Cadance's stomach, the pink mare's penis pressing into both their chests. More pleasure shot through Cadance as she felt a new pressure on her stallionhood, and she and Twilight both relished in its warmth. Eventually, Twilight pulled herself out slightly, then pushed back in, repeating the process a few times. Each small thrust brought tiny moans and whimpers to both of them, their wings flaring as pleasure rocked their bodies.

Twilight soon regained strength in her hind legs, getting up and pistoning her cock into Cadance faster and faster. At the same time, she couldn't help but notice Cadance's cock slapping against her belly with each thrust. She had already sucked her off and enjoyed it, so why not do it again?

"HHHH!!!..." Cadance gasped as she felt Twilight's mouth envelop the head of her stallionhood once again. Twilight soon got into a rhythm of suckling the head of Cadance's penis every time she thrust into her, and that only added to the already blissful state the pink mare was in. As Twilight gave a particularly rough lick to her flaring head, Cadance shouted, "Ahhh!! Twilight! I...I...AHHHHHH!!!!!!"

Everything seemed to hit Twilight all at once. She could feel Cadance's cock releasing its warm, delicious seed into her mouth, all while her own stallionhood was being squeezed by her sister-in-law's climaxing vagina, becoming completely drenched in her marecum. At that moment, the pressure inside Twilight's cock reached its limit, and she moaned loudly around Cadance's head as she came, blasting her fresh seed deep into Cadance's womb. Cadance screamed again as she felt Twilight filling her up with her fluids, slowly relaxing as she basked in its warmth and came down from her orgasmic high at the same time.

After several moments, Cadance, still heavily panting, asked, "hhhh...So, Twilight...hhhh...how did it feel?"

"I...hhhh...can't explain it...hhhh...It was too amazing..." Twilight replied, quietly.

"hhhh...Shining Armor never gives me this much pleasure..."

Twilight no longer cared that she had just had sex with her sister-in-law. "Then...hhhh...maybe I should drop by the Crystal Empire more often..."

"Hmmm..." Cadance finished, the excessive warmth relaxing her, "Maybe..." At that moment, the pink alicorn closed her eyes and fell asleep. Smiling, Twilight pulled her still erect cock from Cadance's depths, a mixture of their fluids pouring out of her. She kissed Cadance on the cheek before turning to face the other two princesses.

"Well done, Twilight," Celestia said.

"Thanks," the purple mare replied before looking over at Luna, "Luna, would you like to go next?"

"It is entirely your choice, Twilight," the night princess replied, "But I would be happy to be your next conquest." Twilight was a bit taken aback by the use of that terminology, but at this point, she didn't care in the slightest. She so badly wanted to feel her penis plunge into another mare's vagina.

Luna lay on her stomach at the edge of the mattress, far from where Cadance was napping. Her hind legs were on the ground, and her tail was raised. Twilight noticed this and asked, "You...you want me to mount you?"

Luna smiled and replied, "Again, it is completely your choice, Princess, but I feel that it would be better if we...mix things up a bit," she finished with another coy smile.

Smiling eagerly, Twilight went over to Luna and mounted her, the tip of her penis quickly finding its destination. She pushed herself in slowly, eliciting an, "Ahhh!!!..." from the alicorn below her. Twilight herself moaned, too, and soon, she was balls deep inside the Princess of the Night.

Twilight wasn't normally one to rush things, but she was eager to feel these sensations again as soon as she could, so she immediately began thrusting in and out of Luna's soaking marehood. The sound of their flesh meeting with every hilt drove Twilight into further arousal, causing her to speed up.

It was quickly becoming too much for Luna. The feeling of being filled and stretched, combined with multiple jolts of electricity from Twilight's ball sack slapping against her swollen clitoris, drove her over the edge faster than Twilight had expected. Her marehood spasmed, then clamped down tightly on Twilight's cock, holding it in place as warm liquids began pouring out of her at a fast rate. Also, under her, the force of her orgasm made her enormous stallionhood twitch vigorously, covering the edge of the mattress in a layer of white, hot cream.

Meanwhile, the force of Luna's climax sent Twilight into orgasm faster than she had wanted, but the purple alicorn wasn't complaining as her cock throbbed, spewing what felt like gallons of cum into Luna's pussy, filling her womb in an instant and spilling out of her a short time later.

Finally, both mares came down from their respective highs as Twilight lay her head between the base of Luna's wings, while Luna herself rested the side of her head on the soft mattress.

Before Twilight could say anything, she felt a gentle hoof on her shoulder. She turned her head to find Princess Celestia standing over her. "Wonderful," she said in a soothing voice, "You're almost done, Princess."

Twilight only moaned in contentment as she slowly stood up, pulling her penis out of Luna and watching as more of her semen flooded out of the now sleeping night princess. She turned her head to Celestia, only to find her carefully lifting Cadance in her magic and placing her next to the other sleeping alicorn, leaving a nice, wide-open spot on the mattress. "Come, Twilight. Over here," Celestia whispered, beckoning her former student with a hoof. As Twilight approached, Celestia laid on her back and spread her legs, much like Cadance had done earlier. Her white member was still as big as it was before, and Twilight realized that if she was going to pleasure Celestia, she would have a hard time fitting the head into her mouth.

This didn't phase the determined purple alicorn one bit, so she climbed atop her former mentor, her head only getting as far as her stomach as she felt the tip of her member poke Celestia's back door. This caused Twilight to jerk back quickly. "Sorry, sorry!" she said in a whisper.

Celestia chuckled. "Don't worry, we can get to that another time. Right now, you must fill me to the brim," she finished in a husky tone. Twilight shivered upon hearing Celestia say that. Never had she heard the grand ruler of Equestria say something so lewd. Nevertheless, this was something she needed to do, and she desperately wanted to do it. HARD.

Twilight aligned herself with Celestia's soaking slit, not wasting any time in pushing herself inside. Twilight moaned loudly as she felt her member become enveloped by another beautiful, amazing set of pussy lips, while Celestia simply gave a soft, "Mmmm..." as she and her former student began their union.

Once Twilight was all the way inside, she rested her head on Celestia's soft, furry chest for a few moments, wanting nothing but warmth and raw pleasure to take over her body. Celestia's fully erect stallionhood was sandwiched between her and its owner, only adding to the blissful heat that Twilight was partaking in. The smaller alicorn felt Celestia's forelegs wrap around her, the embrace letting her know that the Princess of the Sun was enjoying this as much as she was. Soon, Twilight began slowly pumping, hearing the sound of her liquid-covered cock exit her former teacher before she pushed herself back in. Celestia continued to moan softly and quietly as she felt herself getting filled again and again, all while two different coats of soft fur rubbed against her massive member.

Celestia soon put her outstretched wings to use, flexing one of them to gently stroke Twilight's horn, while the other one rubbed Twilight's new, feathery appendages. Twilight gasped in both shock and pleasure as she felt the new sensations coursing through her body, sending waves of pleasure through each and every one of her muscles. She let loose a loud, "Ahhhh!!!!..." as she experienced three pleasurable feelings all at once, the majority coming from the alicorn she was about to fill.

Celestia continued to elicit silent moans and gasps as she continued her ministrations on her former prodigy. "Ah..." she began, her instincts telling her that Twilight was close to orgasm once again, "That's it, Twilight...ah...you're doing great...ah...Let it all out...ah...cum for me..." In order to make sure the young alicorn did so, Celestia increased the pressure her wings were putting on Twilight's own wings and horn, causing Celestia herself to experience a heightened sense of pleasure, as alicorns were very wing sensitive, just like pegasi.

The multiple feelings in Twilight's body were too intense, and with a loud, primal scream, she reached her final climax of the night, shooting her hot seed inside Celestia, all while her own marecum cascaded down her hind legs, soaking the mattress under her. The sudden warmth from Twilight's load, combined with the electricity coming from her wings' ministrations, caused Celestia to orgasm as well, albeit less intensely, as her pussy leaked a generous amount of cum over Twilight's dick and balls, while her own stallionhood shot several spurts of cum onto her chest and Twilight's chin.

In the end, both mares panted heavily as they basked in their afterglow. Remaining in the embrace, Twilight opened her eyes to see several ropes of semen on Celestia's upper chest, so she scooped it all up in her magic and brought it to her mouth, moaning in delight as the sweet, caramel-vanilla flavor washed over her tastebuds. She then used a hoof to clean the cum off her chin, which she put in her mouth, as well.

After swallowing the white mare's load, Twilight pulled out of Celestia and crawled up on her chest, relaxing further into the embrace. She sighed and asked, "D-Did I do alright?"

"You sure did," Celestia replied, stroking Twilight's back, "You shall now be officially recognized as a princess from now on."

Twilight only hummed in delight, happy that this was over with while she basked in her former mentor's warmth. At the same time, she looked over and saw that Luna had begun spooning with Cadance, both mares still fast asleep. Twilight then rested her head back on Celestia's upper chest and quietly said, "I love you, Princess Celestia. I love all three of you."

Celestia smiled and replied, "We love you, too, Princess Twilight." She then leaned down and gave the younger alicorn a kiss on the forehead before laying her head back, both her and Twilight relaxing further until they joined Luna and Cadance in a deep, much-needed slumber.

THE END