When Shining had directed Celestia up the stairs and to Twilight’s room, Celestia had assumed that would mean she didn’t need to knock. She’d assumed every room in the house would be protected by various privacy wards simply due to the proclivities of the library’s inhabitants. The wards on Twilight’s door hadn’t stopped or even slowed her down.

When she opened the door, slipping through the wards and stepping inside, she realized that perhaps she should have knocked.

“Sorry to interrupt, but I need Luna’s input on…” Celestia couldn’t continue her interjection as she had to immediately close her mouth and process what she was seeing.

Her dear sister was at least partially hidden behind Twilight, but the smell of sex was unmistakable. Celestia had interrupted again. Twilight’s death glare was already upon her, but the glare quickly softened.

“Princess Celestia.” Was all Twilight said, though very calmly. She seemed to wait a moment to consider something while Celestia took in the sight, unable to turn away.

What Celestia saw was startling, and also terribly confusing. Luna was strapped with her back on some table, and had her hooves restrained slightly in the air. All four of her hooves were wrapped in some material, and linked to the ground, pressing her flat against the white, cloth covered surface. Twilight was positioned in between Luna’s legs, standing in front of the table. Had they been the same size, Twilight would be blocking most of the view, but Twilight was a much smaller mare. Her head barely hid Luna’s nethers from Celestia’s view, and Twilight’s glistening wet snout was a clear indication of what had been happening. Luna’s wings were unbound, and spread wide against the table, ever so slightly flapping.

Celestia’s mind was focused on the fact that it couldn’t be particularly comfortable to be strapped down like that.

After a few moments, Twilight shrugged and smiled softly. “It’s funny. I warned her that the only pony who would barge in on us without knocking was you. She said that if you did, that you deserved what you got. Apparently, she honestly believes that.”

Celestia looked over her shoulder. “I… I’ll go and give you a chance to clean up…”

Twilight shook her head from side to side. “No. Luna hasn’t asked me to stop.”

That wasn’t something that Celestia expected to hear. This was about to get a whole lot more awkward. “What do you mean?”

Luna’s wings softly fluttered against the table, but Twilight answered. “Luna and I have a system. If she wants me to stop, she knocks three times. Can you demonstrate the knock Luna?”

Luna’s fore hoof slammed firmly against the table, startling Celestia with the loud noise. “Crack. Crack. Crack.”

Twilight nodded. “Thank you, Luna.” Twilight turned and gave Luna’s leg a quick kiss, causing the wings to stretch. “That’s the noise she makes if she wants me to stop. She hasn’t made that noise unbidden, therefore, she does not want me to stop.”

Celestia caught a glimpse of Luna’s twitching pink flesh when Twilight turned, and immediately blushed. She didn’t need to see that. Perhaps she’d imagined it.

Luna’s bits were pink.

Pink.

“I… see… But that doesn’t mean I need to stay. I’ll simply wait for you to finish…“

Twilight frowned, and Celestia saw a brief flash of that angry glare from before. “No. I don’t think so. Whatever you need is obviously important enough for you to fly from Canterlot, then interrupt us during our time.” Twilight took a deep breath, appearing to calm down. “And I know and trust you enough to realize that it’s probably very important.”

Celestia nodded. “It… is.”

Twilight looked back at Luna’s prone body before she answered. “So it seems that Luna is the one who is being bad. Luna, are you being naughty?”

Two quick raps came from the table. “Crack. Crack.”

Twilight turned back to Celestia with a sly grin. “She claims she isn’t. I think she’s lying, and will need some coercion.”

Celestia frowned. “Why does she not speak?”

“The mask is a magic gag. It allows her to breath fine, but keeps her from talking. It’s very effective to keep her from asking questions or telling me things she shouldn’t.” Twilight walked around the table to Luna’s head, revealing the whole obscene view of Luna’s quivering underside in the process. “Since apparently she has some secrets that I shouldn’t know.”

Celestia quickly looked away, but not before seeing more of her sister’s bruised buttocks and wet flesh than she intended to. Luna certainly had secrets that Celestia wished she didn’t know.

Twilight spoke up, attempting to get Celestia’s attention. “Here, see?”

Celestia slowly turned her head back, unhappy at Twilight’s request to look towards her sister’s vulnerable form.

She saw all of Luna once again, and now Luna’s head was being lifted by Twilight so Celestia could see her face as well. Luna was wearing some sort of purple mask that covered her snout and eyes, clearly blinding her. The mask pulsed with magic, and had Twilight’s cutie mark emblazoned on it. Celestia ignored the rest of the obscene scene, and focused on the spell work.

“That’s an impressive artifact, Twilight. The sealing magic involved is honestly terrifying. I’m not sure I could break through.”

Twilight smiled deeply, embarrassed and pleased by the compliment. She sucked in a breath as though that had never occurred to her. “Oh… I suppose not. It does keep Luna at bay when she gets… passionate. Though, it’s not much. You should see what I made for Cadence. She’s got a whole suit. The real magic I made for Luna is over here, come take a look!” Suddenly excited and smiling, Twilight was almost hopping with joy as she walked back in between Luna’s legs and gestured frantically to something between the bound mare’s legs. Twilight was acting like a foal presenting a report card of excellent grades.

Uncomfortably, Celestia approached. She wasn’t sure what to do, and was completely out of her breadth of experience—which was a scary thought, all things considered. The magic in the mask was truly impressive, and Twilight seemed so happy to show it off that Celestia would feel incredibly guilty turning her down. Especially since Celestia was the one who was interrupting.

Against her instincts and better judgment, Celestia steeled her mind to stare at her sister’s genitals where the next charm seemed to be located.

As she approached, she noticed another layer to the setup that she couldn’t see from the door. Luna’s teats were covered by some glass cups that had little tubes coming from them. The tubes ran off the side of the table and underneath to some hidden contraption or storage. There was a gentle pulse of magic, and the cups were half with flesh as they were slightly sucked upwards. Luna softly shook against the table.

Celestia tried to ignore the smell, but it was strong. The scent was indescribably Luna, but far more musky than usual. There was the heavy scent of sex and sweat, and another sweet smell that lingered. Celestia just barely smelled Twilight, but that was normal. The filly always had the faint scent of arousal about her.

Awkwardly, Celestia stood between her sister’s legs. “Well sister, I did not expect to see you like this.”

“Knock”

Twilight chimed in. “Luna agrees.” Then she pointed her hoof at a little speck in Luna’s inner thigh. Far to small for Celestia to see clearly, but far too close to Luna’s very wet pussy for Celestia to approach any closer.

“Look at this one! This is a real work of science and art. It took me weeks to come up with the design, but it’s probably unbreakable. Luna and I have tried, and you’re the only pony with stronger magic than her!”

Celestia squinted. There was a small glowing dot there, wasn’t there? It looked vaguely like some sort of sealing magic, but it did more. “That’s… interesting spellwork… Twilight. What exactly does it do again?”

Twilight smiled broadly. “You have to get closer to see it, but it’s a more complex sealing spell. Can you figure it out?”

This had to be a bad prank. No pony could possibly be this clueless to Celestia’s discomfort, while simultaneously being this nonchalant about sex.

Celestia glanced at Twilight and saw her face filled with pure hope and nearly unlimited glee.

No, this was just Twilight being Twilight. Celestia internally cursed—her sister sure as Tartarus knew exactly what she was going through, and was probably dying from laughter underneath that cursed mask.

Steeling herself once more, Celestia moved her face forward until she could make out the design. Trying her best to ignore her sister’s overpowering musk and twitching flesh, Celestia finally noted the details in the little glowing copy of Twilight’s cutie-mark that appeared to be painted on the naked flesh just outside of her sister’s outer labia.

It was more sealing magic, but this one was focused on Luna’s nervous system. There was also an enhancement charm or two, a sustenance charm, and a powerful divination charm. The whole thing was impossibly well constructed. Celestia knew she couldn’t create something so exquisitely detailed, and quickly found herself enthralled with the spellwork itself while completely forgetting Luna’s obscene canvas.

“This is absolutely amazing Twilight… I daresay even beautiful. I couldn’t guess the function, but I recognize the skill. You’re suppressing part of her nervous system, enhancing other parts, sustaining her, augmenting some senses and dulling others, while protecting her from harm. Where did you learn this?” Celestia tore her eyes away from the creation and focused on Twilight’s beaming face.

“Shiny described the concept to me, but I had to make it. His magic isn’t fine tuned enough for the delicate work, and I had to create the circuits for what I wanted.” Twilight’s cheer was overflowing.

Celestia had a moment of panic. The charm didn’t have to be this small. Twilight knew that, and she knew that. Twilight had gone out of her way to miniaturize this so as for it to be unnoticeable. Shining probably could cast this, or something similar, but it would take a whole suit of armor to carry it. Or you could shave a pony and cover its back, she supposed. Still, the military applications were tremendous, and the mass application of a modified charm to her guard would be happening the moment he failed in his quest. She’d probably ask him earlier, but tasking Twilight with applying the charm to the castle guards before then would surely count as interfering with his plans for her.

“Twilight, I can tell this is utterly ground breaking magic. But what exactly does it do?”

“It dulls pain, protects her body from most harm, provides water, carbohydrates, and proteins as she needs them, increases blood flow to keep her aroused, increases specific hormone flow to make her even more aroused, augments her mucous production to keep her lubricated, and keeps her from cumming!”

Celestia stared blankly back at Twilight. In the moment, she’d forgotten this was a sex toy. “Keeps her from what now?”

Twilight smiled brightly. “Prevents her from cumming. You know, orgasms?”

Celestia did know what that word meant. What she did not know was why that function was on a sex toy. She assumed the point of sex was to have said orgasm. “But… why?”

“Because of the rules! Luna can’t have intercourse, or seek out sexual gratification. I’m not allowed to penetrate her either.” Twilight’s smile was wide, and she looked proud.

Celestia looked over her shoulder, wondering if it would be acceptable to simply leave at this juncture, but decided that she was already this far down the rabbit hole. In for a bit, in for a bushel. “So why is she… like that then?”

Twilight ran her hoof up Luna’s thigh, smiling affectionately. “The rules don’t apply to me. I can seek out sexual gratification all I want. So I am.” Twilight gave a quick and affectionate kiss to Luna’s inner thigh. “Luna and I figured out that as long as she never asks me for anything, and doesn’t cum, it doesn’t count.”

Celestia still didn’t understand. “How did she get like this without asking for it?”

Twilight continued to rub her thigh affectionately, staring at Luna’s pussy as it quivered. Twilight’s voice lowered, softly and affectionately. “The same reason you stayed in the room.”

“That doesn’t make any sense. Luna never asked for me to stay.”

Twilight’s smile turned wicked as she brought her gaze back to Celestia, basking in her own cleverness. “She didn’t have to. She could have tapped ‘no’ for me when I said your name, or tapped three times if she wanted me to take off her mask to talk to you. She didn’t. The only thing she couldn’t do was tap once, because then she’d be asking for something. Instead, she did nothing. Therefore, she wants you in the room.”

That thought was alarming. Celestia glanced at Luna, whose back arched and wings fluttered. “Perhaps she was indifferent?”

Twilight ran her hoof down Luna’s leg, keeping eye contact with Celestia as she gently flicked Luna’s clit. Twilight’s voice was low and sultry when she spoke. “I highly doubt she is indifferent to this situation.”

Celestia gulped.

Luna’s back arched again while her pussy oozed out fluid like a slowly overflowing teacup. There was a single knock as Luna’s hind leg quivered to Celestia’s left.

Twilight’s evil smile turned affectionate, and she gave a light kiss to Luna’s knee. “She seems to agree with me. I’d trust her on this.”

Celestia took a step back, her eyes wide and panicked.

Twilight laughed. “I’ll count this as pay back for interrupting us.”

Celestia’s voice quivered as she tried to understand the situation. “Does Shining know about this?”

“Nope. I don’t tell him about these visits, and he doesn’t ask. He knows I made runes for the rest of the harem, but not for Luna. He also can’t spy through these wards. As far as he knows, we talk about astronomy all night. He’s not entirely wrong. I do spend plenty of time studying the moon and the stars.” Twilight briefly frowned. “Are you going to tell him?”

Luna quickly tapped twice.

Celestia groaned. “I suppose not. At least it means that this little show was accidental on Luna’s part.”

Luna tapped twice.

Twilight smiled. “I guess not.”

Celestia glared at Luna, not that she could see. “Be this… nonsense as it may…” Twilight frowned when Celestia called it nonsense, “I still need an answer from Luna immediately.”

Twilight continued to frown. “Okay. But this is Luna’s court right now. She’s in charge, and I am her attendant. As such, you will present your case to Her Majesty, Princess Luna.” Twilight gestured to Luna’s quivering cunt.

Celestia sighed. This was insane. “She very much does not seem in charge. Please release her, so that she may speak directly to me, Twilight.”

Two taps.

Twilight frowned, and glared defiantly at Celestia. “No. She is in charge. This is her time. I ask her for permission, and she allows it or she does not. Right now, in this room, she is in charge. I am her attendant. You aren’t supposed to be here, so at best you’re a courtier.”

Celestia was done with this. “Twilight, this is absurd. This is about that stupid bet she made with Shining. She’s just try…”

She was interrupted by two very loud raps.

Celestia stopped. If this insane game was how Luna planned on seducing Twilight, then she shouldn’t interfere. “It’s… not my place to complain. Enjoy your time with her, Twilight, though you’ll likely have much more time in the future.” Celestia glared at Twilight in frustration. Luna seemed to be making quite the progress towards her goal. “I suspect she’ll have you wearing that mask soon enough.”

Twilight laughed. “Maybe, though, I doubt it. If she puts me in the mask, I won’t be able to eat her pussy.” Then she lowered her gaze to Luna’s aforementioned anatomy while quickly licking her lips. “And she really likes me to eat her pussy, doesn’t she?”

There was a silent pause, and then Twilight lowered her face. “Your wish is my command, Princess. I will worship you while the courtier presents their case.”

Celestia stood and awkwardly read the missive to Luna while Twilight obscenely… worshiped. Occasionally Luna knocked once or twice, and sometimes Twilight paused her task to clarify. All the while, Luna quivered and Twilight noisily slurped. Twilight had gotten alarmingly good at reading Celestia’s sister when she was bound and gagged. Celestia knew Luna better overall, but Twilight clearly had more experience in this specific matter, and Celestia was willing to defer.

When it was done, Luna had agreed to create a constellation. It would be a yak smashing a pot. Simple, and representative of Celestia’s emotions.

Utterly and completely destroyed.

As Celestia took her leave, she watched Twilight’s slavish attention to her sister. It wasn’t a method Celestia would approve of, but Luna clearly had the mare wrapped around her hoof. Twilight had defended Luna from Celestia with all the vigor that Shining had once demanded she attend Ponyville with him—all while shoving her snout in Luna’s pussy. In a perverse way, it saddened Celestia to see her dedication straying from Shining. “You are a very determined concubine, Twilight Sparkle. I’m impressed at your ferocity in meeting Luna’s desires.”

Twilight looked at her in confusion before wiping her snout off. “No, I’m a very determined friend.”

Celestia stared at her, unsure of what to say. Twilight’s friendship lessons had seemed to be going well, and there was little chance she was confused.

Twilight walked quickly towards her, and from her tense expression, Celestia expected to be slapped or some such thing. Instead, Twilight leaned up to Celestia’s ear and whispered to her. “You should trust your sister more.”

Celestia froze before whispering incredulously back, “Excuse me?”

“Luna wouldn’t be here like this if she didn’t trust me. She’s far more powerful than I am, and she is not wearing any magic inhibitors. You shouldn’t have needed me to tell you that she was in charge. This whole time it hasn’t been me teasing you, it’s been her. I don’t know what’s going on between you two right now, but please think about that. You’re both my friends, and I love you both, but this is her time and not yours.”

Twilight kept surprising her in new ways, but in this case she had been right. Celestia and Luna’s relationship had been oddly tested here, and Celestia had kept second guessing Luna and her motives at every turn. Supposedly, Celestia trusted Luna and Twilight.

Supposedly they were friends.

Suitably chastised, Celestia answered. “You’re right. Thank you.” Celestia bowed her head in deference, or perhaps gratitude for the correction. Ponies usually weren’t willing to correct her when she made a mistake, especially one involving her sister. For a brief moment, Twilight’s willingness to help her warmed her heart.

She kept her head bowed as Twilight leaned in again. Celestia waited patiently to hear another line of friendly wisdom.

Instead, her ear was nibbled, and Twilight whispered hotly. “Everypony in Shining’s harem gets my full attention when it is their time. You will, too.”

Celestia mechanically lifted her head from the bow, clumsily turned around, and wordlessly stormed from the room. She nearly got stuck in the doorway as her wings were stretched to their limit.

Author's Note

Oh hey. Something vaguely approaching porn in one of my stories. Hopefully I made it awkward enough to where it's not actually arousing. Then again, nothing I write is, so there is little worry about that!