For hours the Royal Guard had been searching the castle grounds for Princess Celestia. Everywhere they looked their search came up empty. It wasn't uncommon for either of their Princesses to leave the eyes of the Royal Guard, but when those moments occurred at least one or two ponies had knowledge of where they went or at the very least, a way to contact them in case of an emergency.

This was one of those rare moments when neither fail-safe was working.

The Royal Guard proceeded to do what they were trained to do. They wouldn't panic, they would scour every inch of the castle, the city of Canterlot, and all of Equestria if that's what it took to find Celestia.

After a few hours of searching it was time to notify Luna of the current predicament.

******

Luna sat naked on her bed, back propped up against her headboard as she enjoyed the sight before her. Eventually, she sighed and spoke.

“Well, pet, I believe it's time to begin your training again. I most certainly hope you won't disappoint me this time... but I'm not holding my breath. You still have a long road of training ahead until you become my perfect cocksock.”

Standing at the foot of her bed was her sister, Celestia, her whole body completely on display. A perfect body that all stallions lusted for, her perfectly sized breasts still held their perk over all these years, a recent addition to her chest were the small subtle nipple piercings that her sister had commanded her to get. Her legs and ass were not to be outdone either as the strong lean muscles lead your eye up to that deliciously firm, yet plump rear. The other side held a prize that few ponies ever had the chance to gaze upon.

Her puffy, tight, and glistening pussy. Or as Luna now dubbed it, one of her 'cum-holes'.

With her legs spread wide, any onlooker could see her pierced clit as her marehood desperately winked. Getting that piercing was another command from Luna that Celestia couldn't disobey. All of them hurt like Tartarus when she got them, but her clit piercing was by far the most painful. Now all her piercings just granted Luna new ways to punish and torment her pet.

All of this stood before Luna as Celestia just avoided eye contact and stared at the floor. Luna lit her horn, using her magic to open a large trunk located at the foot of her bed, and pulled out the equipment that would be used to train and torment her pet tonight.

In front of Celestia, held within Luna's magical aura floated two long lengths of rope, a thick collar, a magical inhibitor ring, a large butt plug, and a vibrating dildo. Within seconds, Luna had her pet tightly bound with her arms snugly secured behind her back and wings restrained to her sides. Finishing off the bondage and making sure that her pet would be completely powerless, Luna placed the magical inhibitor ring firmly down on to Celestia's horn. The moment the ring was placed on her horn, all of Celestia's strength and magic was instantly muted. Struggling against her bonds was now a physical chore. It really drove home the fact that she was completely helpless now and was at the mercy of her mistress.

Luna used her magic to bring Celestia atop her bed, dropping her pet between her spread legs, her muzzle just inches away from Luna's marecock. It was by far the largest Celestia had ever seen and Luna would make sure she would be able to take all of it, in each one of her holes.

Luna sat up against the headboard even further, hands behind her head, enjoying the sight before her, Her older sister bound between her legs, ready to continue her training and for Luna to gain some much-needed stress relief.

“You may begin whenever you're ready pet, but the longer you wait, the more torment I will bring upon you.”

Celestia met her sisters gaze, empty and glazed eyes looking into Luna's, She began to slowly crawl and inch forward to take her mistress's cock into her maw.

The glazed look slowly faded from Celestia's eyes, she stopped just short of taking the head of Luna's cock into her mouth. The fog clouding her mind was starting to dissipate, her thoughts and memories were coming back to her. She felt weak and restrained, when she tried to use her magic, nothing happened. She could feel her arms, legs, and wings were bound by rope and without her alicorn strength, she would be unable to break free. She had one option for escape and that was to scream for help.

Luna stared into Celestia's eyes, once again she had broken free from the powerful charm on her mind.

Luna would have to reapply the charm.

Luna smirked and slowly shook her head as she lit her horn Luna's as Celestia's mouth opened. A muffled scream was all that was allowed to escape before Luna's magic forcibly shut her whore's mouth. “When will you just quit fighting, pet? Tsk.. tsk.. tsk... Eventually, you'll come to accept your new role as my cocksleeve and I won't have to worry about you being an impertinent pet.”

With a quick charge to her horn, Luna's magic enveloped Celestia's head as the charm on her mind was reapplied and strengthened even more this time. As much as Luna enjoyed seeing her sister try to fight and lose each time, she was beginning to grow tired of it.

Celestia's eyes resumed their glassy, glazed, and empty appearance.

Luna's smirk quickly turned into a wide grin as she began to condescendingly talk to her sister, now turned back into a semi-mindless sexpet.

“Now pet, your mouth better get to work, I have quite the rigorous training schedule planned for you, but don't worry with me diligently overseeing your training, You're going to be perfectly molded into the perfect cocksock. No matter where I decide to stick my cock you'll be able to obtain pleasure. Doesn't that sound great?”

Nothing but a whimper and a nod came from Celestia as she opened her mouth and slowly squirmed forward so she could take Luna's large cock into her warm wet mouth.

A large bead of precum had begun to leak from the massive cock, Luna just sat there on her bed with a smug look as Celestia closed the remaining gap between her mouth and Luna's cock. Right before Celestia could start, Luna lightly smacked her pet's cheek to get her attention. “Uh, uh, uh” Luna chided. “Eyes up here when you use your mouth. I love to see that helpless look in your eyes as you impale your throat on my cock.”

Celestia nodded again and brought her gaze up to meet Luna's as she opened her mouth and engulfed the head of Luna's cock. With a flick of her tongue, Celestia grabbed the leaking precum and allowed it's salty taste slide down her throat. Celestia's eyes never left Luna's as she started bobbing her head slowly back and forth, taking in more of the shaft each time. Her tongue massaged the underside, occasionally coiling around the thick cock to tease and toy. She sucked hard, sending tingles through Luna's body.

Luna grunted and shuddered in pleasure as she slowly brought a hand up to her pet's mane. Gliding her fingers through the colorful hair and slowly applying pressure to the back of Celestia's head, forcing her to take the cock deeper and deeper.

As Celestia continued to mouth massage Luna's cock, the scent and taste started to overwhelm her senses as it slowly imprinted itself into her mind.

Luna decided it was time to slowly prepare her pet's other orifices and provide some positive reinforcement.

Luna's magic grabbed the large rump of Celestia and spread her cheeks wide. Forcing a small moan to emanate from her pet's throat. “Oh, do you like it when your ass is played with, pet. Don't worry I'm only going to start you off with a plug that is only half of my girth. You should be able to take it with only a medium amount of pain.”

Luna chuckled at the last comment and floated a bottle of lube above Celestia's ass. A decent amount of lube was squirted on to Celestia's tight pucker as Luna's magic prodded it slowly into her pet's ass, forcing louder moans from the cock gagged pet.

The plug was floated up and unceremoniously forced into Celestia's tight asshole. As the apex of the plug's girth was reached, a muffled scream came from Celestia. Luna was tempted to leave the plug as it was once the scream came, just to torment her cocksleeve and because the vibrations from the screaming were truly an amazing feeling. It alone almost caused Luna to cum right then and there, but she wasn't ready to feed her pet just yet. With a firm push from Luna's magic, she was able to firmly seat the Butt plug adorned with Luna's Cutie mark at the base into her sister's ass, turning the muffled scream into a deep moan.

Luna patted the head of her pet. “There there, that wasn't that bad, now was it? Now it's time to fill that cunt of yours.” Luna leaned over the back of her pet and gave her ass a firm swat, causing another shriek from the mouth of her pet.

All these vibrations on Luna's cock were really testing her stamina.

Luna's hand ventured down away from Celestia's ass and towards her dripping cunt. When Luna placed her hand atop it her hand was immediately soaked with a small deluge of mare cum. The fur between the inner thighs of Celestia was absolutely soaked and matted from the wetness.

“My, my, You came just from putting a plug in your ass and sucking my cock, huh? You are quite the horny royal bitch.”

Luna leaned back and basked in the feeling of her slut's mouth bobbing on her cock. With a burst of magic from her horn she levitated the final toy that would complete the filling of her cocksleeve in training. An innocuous looking vibrating dildo floated just outside the soaked entrance of Celestia's cunt.

“I hope you enjoyed that little orgasm you just had because now I control when you cum. This little toy going into your cunt is enchanted to slowly train you to take my cock, it will grow, stretching your cunt to take me perfectly. Along with that, it will constantly vibrate and stimulate you with limitless pleasure, but keep you on the edge of orgasm. Only I am the one who can remove this toy and let you cum. I control each one of your holes and there's nothing you can do about it.”

Luna bucked her hips upward into Celestia's mouth, forcing her cock into Celestia's throat. This new sensation caused Celestia to gag and sputter on Luna's rod, drool and spit coming from her mouth and sloppily coat Luna's cock. While Celestia continued to sputter, Luna slid the dildo easily into her pet's pussy.

Immediately it's magic started, powerful vibrations ripped through Celestia's pussy causing her to scream from the sensation, these screams were muffled by the cock stuffed in her throat. She continued to look up into the eyes of Luna as her body shuddered in small tremors from the pleasure of being completely filled in all her holes and pleasing her mistress. The only things on her mind were pleasing and obeying her sister. Celestia rode the pleasure to right before its peak and prepared for the rush of an orgasm, but it never came. Celestia was stuck waiting to reach the peak. She whimpered and struggled against her bindings, trying anything to possibly ride another orgasm.

If she could she would be begging for release.

Luna grunted as she felt her own orgasm nearing, the constricting spasms of Celestia's throat were milking her cock and bringing her closer to busting down her pet's throat. “Now that all your holes are full, We can start properly training your throat. By the end of tonight, I expect you to be able to get all the way down to the base. Eventually, my cock will live in your throat and you'll learn to love it..” Another grunt was forced from Luna as she wrapped her hand around the base of Celestia's horn, gripping it firmly she yanked down, hard. Luna's cock traveled down the rest of Celestia's throat, causing a thick bulge to form from Luna's girth as Celestia's breathing was cut off.

Luna chuckled as she looked down and sneered at her helpless little cocksleeve. “Remember pet, breath through your nose.”

Celestia's throat was squeezing Luna's cock like a vice, the sounds of heavy gagging filled the air, mixed with wet slapping and choking, she swallowed as best she could to try and stimulate Luna's cock further. Celestia's muzzle took the cock whole, balls to her chin, entire shaft down her throat. Her eyes watered, streaks of tears trailing down her cheeks from the sheer intensity and girth that Luna began fucking her face with.

Minutes passed, Luna's assault not stopping for a moment. Celestia's face had turned a light shade of purple, doing her best to pleasure the cock while Luna used Celestia's horn as a joystick to control the tempo.

Luna began to speed up the pace even more, deciding it was time to feed her pet. “Get ready for your meal, you cum-slut. This will be the only thing you're allowed to eat from now on, but don't worry I will make sure I never neglect to feed you. You are my prized possession after all.”

A firm knock came from the door to Luna's chamber. Slightly caught off guard by this, Luna panicked for a moment before speaking. “O-One moment please.”

Luna surveyed her room, making sure nothing obscene was out in the open. After that she took her comforter and covered Celestia's form, making sure she was hidden from sight as she continued to use the horn to keep her buried all the way down to the base.

Luna's horn glowed and she cast a simple silencing spell on the comforter. Any sound coming from underneath would not be heard by anyone on the other side.

Celestia's head was frozen in place, muzzle right up against Luna's crotch as Luna held her horn tightly, forcing her to take it all, and continue to slowly suffocate.

“You may enter,” Luna called across the room.

A lone guard stood in the doorway as he opened the door to Luna's room, he made eye contact with the Princess of the Night as she sat in her bed, blankets gripped firmly to her chest.

Luna gave the guard a nod, prompting him to speak.

“Princess Luna, are you alright? Your sister is missing, and we heard a lot of noise coming from your room.”

Underneath the blanket Celestia began to panic, her face was turning purple at this point and she was clearly running out of air. Her throat began to convulse rapidly as her lungs burned for air. She tried her hardest to pull her head back and get any amount of air that she could, Even tried using magic, but the ring on her horn stopped that immediately. Luna's grip held her down despite her attempts at escape.

Luna's grip tightened on her pet's horn as she squeezed even harder. The throat her cock was buried in was now making it impossible to hold back her release. That and the thought of her slut panicking as she thought her air supply would run out.

Luna looked up to the ceiling pretending to think about the guard's inquiry for a moment as she almost inaudibly grunted and began to flood Celestia's throat with her seed, making sure to keep her pet well fed.

Luna looked back at the guard as her orgasm continued but slowly tapered off.

“I am well, Thank you. As for my sister, she often wanders the castle at night, no need for concern. I'm certain she will turn up eventually.”

“Okay Princess, sorry to have disturbed you. I will notify the other guards as well.”

The guard turned and left, closing the door behind him. Off to notify his commanding officers of Luna's response.

Once the door was closed, Luna removed the comforter from her bed, leaving just her and the purple-faced cocksleeve on the bed, her face pleading for air as her throat gulped down spurt after spurt of delicious seed. The orgasm lasted longer than usual, seconds ticking by as Celestia half-suffocated on the cock, half-drowned from the prodigious load, cum had even started to come out of her nostrils.

Eventually, spent, Luna released her horn.

Instantly, Celestia jerked back, the cock slicking back out of her throat and mouth as she gasped for air, coughing. Cum spilled from her mouth onto the bed.

“I hope you know,” Luna said, feeling smug. “That you’re going to be licking up the mess you’re making... Overall not a terrible start to your training, but you have much, much more ahead of you.”

Author's Note

I'm pretty happy with this. Hopefully, this will be part of a couple of stories following Luna and Celestia, but who knows?

If you liked it Hit the green thumb and tell me your favorite part with a comment.

If you don't like it hit the Red thumb and tell me why with a comment.