Pre-chapter warning: Lots of age differences in this one, though everyone's over 18 as usual and consents fully to everything involved. Also some only-technically-legal-because-they-just-graduated-or-quit behavior. You've been warned.

Newly-not-nurse Redheart was resolved: she was going to show the potion to the vice-principals during her exit interview.

She'd thought about not doing it, of course. She didn't feel it was technically covered by confidentiality for many reasons, chief among them that sharing the presence of a weird substance at the school didn't mean revealing where she got it, and that magical sex drugs from another world were pretty much outside the scope of terrestrial legislation. But she did feel that perhaps, in spirit, it was. It wouldn't be hard, after all, to make the leap that one of a handful of students must be the source.

At the end of the day, though, she felt it was her duty. The vagaries of school budgeting, plus her own timetable for her new job, meant she couldn't stay long enough to train or even meet her replacement. It would thus fall to the school to let the poor fool know what they were in for, and she felt it was critical to the well-being of the students that she give as much information as possible. While Sunset and her crew would of course be gone, many of their friends were rising seniors or even younger, and she expected at least a few bottles of the potion to appear within the next year. She'd also heard a disturbing rumor from Pinkie Pie that a new generation of weird creatures might appear in the school sooner than one might expect. All in all, better to leave her successor as forearmed as possible. They'd certainly need it. Besides, with all the likely sources already graduated, it seemed safe to reveal.

So she repeated to herself for the thousandth time as she walked through the heavy July air to the house the vice-principal sisters shared, not far from campus. Her timetable was so tight she'd had to leave for job training the day school ended; she'd even had to miss graduation, to her sadness. So there'd been no time for the exit interview. Fortunately, she'd be in Canterlot for her actual assignment, so now that her training was done, she could come back and fill them in.

She'd had plenty of time during the intervening weeks to convince herself telling the principals about the potion was the right thing to do. Or, well, not quite. If she was honest with herself, figuring out it was the right thing to do was easy.

What wasn't so easy was stopping herself from getting so damn horny at the thought.

Redheart had always been comfortably straight, in that she'd enjoyed sex with her two college boyfriends. She'd briefly considered whether she might also like sex with women, then remembered the feeling of a nice warm dick inside her and decided to stay with the men. Then she'd thought about sharing the effects of the potion with her former bosses, and she'd discovered something new - she mostly just liked the warm dicks.

She always would have said that Luna and Celestia were attractive women. Though her access to the school medical records ensured she knew they were in fact true biological sisters, she'd hardly have believed it otherwise; they seemed to her as different as night and day. Celestia's warm, welcoming personality was matched by her pleasantly curvaceous body, one that seemed as suited to the stereotypical welcoming bar girl or sturdy peasant woman as to her true job, though Redheart knew she could be firm when needed. Luna, in addition to the obvious skin and hair contrast, was far slimmer, nearly pixie-like in build, but to Redheart even more attractive.

The first time her mind idly considered what might happen if Luna drank the potion, she knew she was in trouble. From then on, every time she made herself think about telling them, she'd rapidly become aroused. She told herself everything - that they were far older than her (though she wasn't really sure how old). That they were still basically her bosses. That it would be fantastically unprofessional. That it would under no circumstances happen regardless. Still, every time ended up with her in the training facility's bathroom, trying to keep as quiet as possible while she brought herself to orgasm thinking of one (or both!) of their magical dicks inside her.

There was nothing for it, though. The time had come. With a sigh, a heavy heart, and panties as heavy with damp heat as the summer air, she headed to the interview.

Celestia knew well what the students said about her sister. "The Principal of the Night" they called her. A pretty good joke, Celestia had to admit. While it was of course technically true - Luna was the primary contact for after-school activities and night-time alarms or other issues - it also described her uncanny way of knowing things. Luna's past as something of a delinquent was an open secret at Canterlot High, and while she used her knowledge of the furtive dealings students invariably got up to only for safety reasons, never for disciplinary ones, she was nonetheless viewed with a mixture of fear and awe by the shadier students. This was especially true now, several years into her tenure as vice-principal, after she'd run into several recent graduates and talked quite casually to them about shenanigans they'd been convinced had gone undetected by all the school's adults.

All in all, this reputation suited Celestia well. She genuinely enjoyed being "the good one", and felt that students who were uncomfortable with their part in some teenage antic or other were far more likely to come to her for help when they suspected Luna already knew their secrets. Which, in her mind was all to the good.

Besides, it meant no one suspected Celestia herself. Only her sister knew that her own sources and knowledge of the goings-on a the school was even more extensive. In fact, while Luna did occasionally get a scoop on Celestia, it was much more common that she fed the "Night Principal" information. She told herself it merely made sense - Luna needed to know, after all; the night contact had to be aware of things that might happen after hours. But for the most part, she had to admit to herself, she just liked having that secret part of her. It was not the only secret she shared with her sister, though; the students also remained blissfully unaware that Celestia had a weakness for pranks rivaled only by Luna. Throughout their childhood they'd engaged in frequent prank wars, and indeed had not slowed down since.

Tonight, the evening of former-nurse Redheart's exit interview, Celestia was in an unusual position: she felt she was heavily down in the prank war. Luna had gotten her good last Tuesday, a prank so well executed that even now she refused to think on the details. As a result, she'd needed something really special to regain her traditional dominance and restore the sisterly balance.

Fortunately, she knew something that Redheart knew, and that she was pretty sure her sister didn't. A certain secret that, deployed right now, would embarrass Luna for some time to come. And, as an added bonus, it was possible she'd get to find something out about Redheart, as well. Celestia did love knowing it all.

As Redheart's interview was winding down, she found herself cursing her decision to save the potion for last. Of course, the structure of the interview made it easy - the vice-principals asking questions, then Redheart responding. It was hardly likely they'd ask about alien potions at any point in that process, and the "do you have any other feedback for us" stage at the end was, she told herself, the natural place to bring it up.

Still, it didn't make her feel less like she was putting it off, or do anything to decrease the increasingly awkward dampness between her legs. Finally, though, they finished up with the last of the planned questions.

"Thank you so much, Ms. Redheart," Celestia said in her wonderful warm tones. "I'm sure you'll have a few things to bring up yourself, after an eventful term. But first, I have to say my voice is a bit tired, and I've finished my water. Luna makes a wonderful herbal tea, very soothing on the voice. I can never get her to tell me what's in it. I'd love a cup before we go on, if you don't mind, Luna." Luna shook her head. "Thanks. Ms. Redheart, would you like any?"

"Sure," Redheart said. Her water was also empty, though more because having something to do with her hands was seeming increasingly important.

"You know," Celestia said, after some brief small talk about Redheart's new job, "I could use some cookies as well. Luna," she called louder, "get a cookie plate?" Luna shot back an agreement. "I think she might need some help carrying, Ms. Redheart. Do you mind? I'd like to organize my notes a little." Celestia had made copious notes during the exit interview, while Luna seemed to have jotted down only a few things.

Redheart shrugged, thankful for the reprieve, and feeling a slight thrill at being alone in the kitchen with Luna, though she realized it was irrational. Still. it did not abate as she entered and saw just how nice the other woman looked from behind as she stood on her tiptoes to reach the cookie box from the top shelf.

"I'm here to help carry," Redheart said, trying not to sound awkward. The tea seemed already to be ready - two steaming mugs were sitting on the counter.

"Oh, thank you," Luna said. "Do you mind taking the tea while I get these cookies ready?" Redheart shrugged. "Great! Be sure to give this cat mug to Tia, it's her favorite."

Redheart grinned and brought the two mugs out. She gave Celestia the mug indicated, then took a sip of her own. It was a bit hot still, perhaps, but remarkably smooth and soothing.

"It's good!" She said.

"I like to give mine a few minutes to cool," Celestia said, hers as yet untouched, "but it is remarkably good, agreed. One of Luna's many talents."

Luna returned with a variety of cookies, and put them on the coffee table before settling back down herself. She took a sip of her water.

"Now then," Celestia said, "let's finish up. Is there anything you'd like to cover that we've missed so far?"

"Well," Redheart started, speaking slowly and pausing to try to gather her courage. Only the potion really remained. It was now or never.

Across from her, Luna seemed to be fidgeting. She took another long swig of water. Redheart froze for even longer, mind racing. She knew Luna's reputation. Did the Principal of the Night know too? Some of her fantasies had started this way...

"Recently a student came to me with a, uh, unusual issue," she stammered a bit. It was impossible to miss Luna's fidgeting.

"Oh," Celestia said smoothly into her increasingly slow and awkward narrative. "A potion, yes? From Sunset Shimmer?"

Redheart's eyes widened. Shit, she thought she already knows. Luna must have told her. Now I look like an idiot.

Celestia was looking right at Luna as she continued, making Redheart's fear even more acute. "A potion that, when taken orally, has the remarkable property of giving a woman a penis. With associated, ah, intense arousal. Is that right?"

Redheart nodded glumly. "I didn't know you knew."

"Don't worry," Celestia said, "I appreciate you letting me know. And I believe not even Luna knew about that one." This puzzled Redheart. "I heard it very much by chance. Still, you're right our next nurse will need to know. It seems likely that our current seniors aren't the only ones who have access to it." She looked again significantly at Luna.

"The water," Luna said, stammering a bit and glancing at her glass, left unattended while she'd made tea, "Tia, this is low even for you."

"After last Tuesday? You know you have it coming. Please pardon us, Ms. Redheart, I must admit Luna and I have something of a decades-long prank war going. Please don't tell the students, it would make it much harder to keep order."

Redheart didn't get it, and then she did. Slowly, uncontrollably, her eyes were drawn to Luna's crotch, where she could easily see a telltale bulge. She tried very hard not to squirm. She regretted her choice of a skirt, long and professional though it was, instead of dress pants. She'd worried the pants might develop a visible wet spot, but now she was terrified that the smell of her arousal would escape.

"In front of a-a guest, t-though," Luna gritted her teeth, "and an e-employee, no less."

"Not anymore," Celestia said, "not for several weeks. Besides, you're the one who brought it up. You could have just suffered in silence and left our guest none the wiser. I do hope you'll excuse her for a moment, Ms. Redheart, she should clearly go to the bathroom and take care of her little issue."

Luna looked like she was going to argue, then thought better of it and sighed. As she rose her women's dress pants clearly strained at the very appealing looking new addition - they were not designed to hide such a thing, and so did very little to do so.

"W-wait," Redheart was shocked to hear herself speaking, though she didn't really try to stop. "I've s-seen this before. You should probably let me take care of it." She was on her feet, moving towards Luna.

"I'm pretty sure I can figure it out," Luna looked confused.

"Dear sister," Celestia laughed, "can't you tell our lovely former nurse's interest isn't really medical? I think she'd rather enjoy helping you out with this one."

"Oh," Luna's already dark cheeks went nearly night-black. "W-well, that seems very unprofessional."

"Ms. Redheart," Celestia said, "are there any other issues you'd like to discuss before we officially conclude your exit interview?"

There was probably no issue important enough that Redheart would possibly have said "yes" in that moment. Fortunately she was spared the ethical conundrum by having genuinely covered everything.

"No," she said, "the potion was the last, and I guess you know all about that one."

"Well then," Celestia said, "this interview is officially over. Thank you for all your good work for Canterlot High, Ms. Redheart. You're now have no professional relationship with the school whatsoever, no matter how tenuous. Proceed to offer a completely non-professional interaction to my dear incredibly horny sister."

Redheart gulped. This wasn't exactly how any of her fantasies had gone, but it was close enough. She licked her suddenly dry lips, which she realized only after the fact might have looked like intentional seduction. Luna certainly seemed to see it that way; her cheeks darkened further.

"I'd really like to," Redheart managed in a week voice.

Luna thought for a long minute, still blushing furiously. She looked Redheart up and down, then nodded and sat heavily back on the couch, legs slightly splayed. "Yes, please."

Redheart couldn't forget Celestia's eyes on them, though the light sister remained shockingly controlled. But she hardly cared. Eagerly she pulled down the zipper of Luna's dress pants and unbuttoned the button. The overstrained garment nearly burst open, revealing panties completely unequal to the task - several inches of Luna's deliciously dark shaft protruded, head damp with precum. The glorious cock was pressed close against Luna's taut belly by the tortured elastic. Redheart hooked her hands under both pants and panties, relishing the other woman's surprisingly cool skin against hers. Then gently but firmly she began to pull down. Luna thrust her legs up slightly, letting the pants get clear, and then she was laid bare before Redheart's eager eyes.

It seemed she'd shaved clean for whatever reason - none of her remarkable hair was visible around her shaft. Though on some women as slender as Luna the effect might have been to make them look disturbingly young, Redheart thought here it just made her look sleek, in a way that only made her more attractive.

Luna's cock itself was large, and darker even than her other flesh, a deep, rich purple. Redheart could have sworn stars twinkled in it, but she was so horny she couldn't trust herself to be confident. Redheart thought it looked delicious, and moved to act on it.

She began by gently kissing Luna's balls, astounded at how heavy they were, despite Muffins and Pinkie's reports. She thought about where all that weight would end up, and shivered. Then she kissed slowly up the shaft, teasing Luna a bit. The vice-principal responded by running her fingers through Redheart's pink hair, then grabbing, not quite so hard as to hurt, but firmly enough to bring a gasp of pleasure. Redheart took the hint. She brought her lips up and took the whole head of Luna's cock into her mouth, savoring the slightly salty taste. It was somehow richer than the few others she'd had, as well. This seemed far better already than that. Eagerly she took more and more into her mouth. She was too distracted to focus on technique, and too inexperienced to have much anyway, instead exploring the wonderful magical organ with her mouth, relishing the tastes of Luna's flesh and her precum. Dimly, she recognized her fellatee's breath coming heavier and heavier.

"Be careful, Ms. Redheart," Celestia's warm voice came dimly through her haze of lust, "I hear these potions make it dangerous to let the user finish in your mouth."

Redheart blushed at the reminder that they had an audience. She desperately wanted to feel Luna inside her, regardless, but she felt so exposed, she wasn't sure she had the courage to go through with it. Still, Celestia was right - she couldn't swallow a load like that, and getting it all over her face didn't sound any better. Still undecided, she removed her lips and began vigorously pumping Luna with her hand. Though the shaft remained rock-hard, and Luna pressed back into her in arousal, Redheart didn't miss the little sigh the Night Principal let out as she removed her lips.

That made up her mind. She might get too embarrassed to fulfill her own fantasies, but she couldn't also let Luna down. Keeping one hand on the delightful member, she moved the other up, brushing it across Luna's flat stomach as she pressed up the other woman's shirt. Taking pity on Redheart's one-handed efforts, Luna reached her own hands down and deftly removed it, then shed her bra, freeing her small, firm breasts. Redheart let out a low breath at the sight, then squeaked as Luna began unbuttoning her dress shirt. In moments, the experienced vice-principal had removed it as well as her bra, freeing Redheart's own alabaster breasts. Luna nodded, face still flushed, and licked her lips. Redheart had no doubt that was intentional, and it was enough to banish her final reluctance.

She removed her hand from Luna's cock and rose, getting ready to reach under her skirt to remove her panties, but Luna was ahead of her. As soon as Redheart moved her hips close enough, Luna's hands were against her thighs, teasing, then before she could react, under the band of her panties, and then they were gone, and the panties with them. Luna lay back with a little smile, dick full-mast and slick with precum and saliva.

Redheart gulped, then lifted herself up. She was strangely reluctant to remove her skirt, the last bastion of her modesty, and instead left it on, pulling it up to clear Luna's cock before settling herself down upon it. Though the garment theoretically left some doubt as to what was going on beneath, the tiny moan that escaped Redheart's lips when Luna's head spread her open, and the deep moan both women let out when, not long later, she settled all the way on Luna's balls, left little doubt about how deeply Redheart was speared by her former boss.

Redheart had never taken a cock so long or quite so thick before, though it was not large enough to be unpleasant. Instead she paused for a moment, savoring the feeling of fullness, then began pumping her hips on the delightful member, unable to contain her heavy breathing. Overcome, she pressed her lips into the soft skin of Luna's neck, ravenously kissing and sucking. Luna moaned, and Redheart felt the other woman's hands go to the buckle of her skirt, then pause. She looked up, seeing the question in Luna's eyes, thought a moment, then nodded. Luna undid the clasp and threw the skirt aside, leaving both women completely naked. For a moment, the knowledge of her exposure to Celestia gripped Redheart. She knew that the angle left nothing concealed: not the obscene sight of Luna's dark cock plunging in and out of her alabaster body, not the sight of her asshole between her generous, spread cheeks as she rode it. Then the knowledge somehow stopped bothering her, and instead just made the already incredible experience feel even more deliciously forbidden.

"My dear Ms. Redheart," Celestia's rich voice couldn't help but draw Redheart's eyes to the source. Somehow the older sister still sat in her chair as always, looking utterly composed. "You really do have an exceptional body. I don't know where all the poor female-attracted students of Canterlot High will get their fantasies without you."

"D-did they really...."

"Of course! You shouldn't be surprised. You're young, attractive, and of course there's the whole 'nurse' thing. What, did you tell yourself they were just hard or wet during exams because they're always hormonal?" She finally took a sip of her tea. "Oh well, they're teenagers, I'm sure they'll cope. And I suspect my sister will have her fantasies taken care of for quite some time." Luna did not visibly react, but she thrust her hips against Redheart, drawing forth a gasp.

"You don't have to watch," Luna grumbled.

"I like a good ass as much as the next person," Celestia took another sip and winked at Redheart, face still serene. "Besides, I do so enjoy reveling in a good prank." Sip.

Unexpectedly, Luna smiled a wicked little smile, though her coupling with Redheart barely slowed.

"That's good," Luna said to her sister, "I wouldn't want to miss this." Celestia raised an eyebrow, then a very slight blush appeared on her cheeks. "I knew about the potion too, you know," Luna finished.

Celestia looked at her teacup with growing horror, despite the adorable cats.

"You...told me...her favorite," Redheart managed.

"I wouldn't lie to you, you're far too pretty," Luna said, "it really is her favorite mug. But I did spike it."

Celestia stayed sitting, still rigidly proper, but now silent. Redheart looked down, and the unmistakable tent was in her pants too.

"Feel free to enjoy the show, sis," Luna winked. "If you need to go, we understand."

"Nonsense," Celestia said, "I'm fine. Unlike you I can deal with my arousal like a grown-up."

Luna rolled her eyes. "This feels pretty adult to me." She thrust her hips into Redheart, who moaned.

Redheart thought a moment, then decided she'd already come far enough.

"Y-you don't have to," she said, "let me help."

Celestia arched an eyebrow at her. "Are you sure? There's no need to pity me, I promise I'm fine."

"I don't p-pity you," Redheart gasped, "I want you."

"Both sisters at once? You are ambitious. I don't think anyone's had that since I was in college, and Luna was in high school. Isn't that right, sis?"

Luna nodded. "And it took three of them."

"I want to," Redheart said.

Celestia just grinned, and walked over. She shed her jacket before she'd even left her chair, and her blouse and bra not long after. Her breasts were as white as Redheart's own, but larger, with nipples and aureolae to scale. And, as Redheart had suspected, her hips were wider and her body fuller than her sister's. She'd look like a classic fertility goddess...except that with the new tent between her legs, she'd be the one doing the fertilizing.

She seemed to be leaving it for Redheart to reveal, and despite the heavenly distraction of Luna still pounding away inside her, she did so. The member was longer than Luna's but slightly less thick. Unlike her sister, Celestia kept a well-trimmed bush, and to Redheart's shock the multicolored hues of her hair repeated here. The long shaft was white like a classic statue, and Redheart would have sworn it glowed. And where the heads of other cocks she'd seen had been slightly darker than the surrounding skin, Celestia's was...indescribable. She might have called it grey, but somehow it was dynamic, and though she could not swear it was real, it seemed to swirl with color, like mother-of-pearl.

Either that, or she was so addled from being pounded by Luna, and so drunk on hormones and fantasy that she'd lost all touch with reality. But either way, it looked delicious and ready, and Redheart eagerly took it into her mouth. She no longer even cared about the impossibility of swallowing the load - she looked forward to Celestia's thick, hot cum dripping over her body. As she began working the shaft with her hands and the head with her lips, she decided she'd try to take it on her breasts.

As for Luna's load, she had no intention of letting that go anywhere but the obvious. She'd seen Muffins' belly swell up with Sunset's seed, and was intensely curious as to how it would feel, and intensely aroused by the idea of finding out. The sensations were crashing over her now - Luna keeping a steady rhythm into her womanhood, Celestia's sublime taste wafting down her eager throat, smooth and soothing as the tea. But one of the underrated traits of a school nurse was a certain detachment, and she could keep a small part of herself in control, observing, even as she felt the tide of her own orgasm rising.

And she determined she'd not let it wash over her until Celestia was taken care of. So even as she clenched and stroked her eager pussy on Luna's sublime cock, she went to work on Celestia's, focusing on her tongue and lips, trying to urge the vice-principal to pleasure as quickly as possible. Eagerly she lapped at the head and base of the shaft, and eagerly she took it between her tight lips, deeper and deeper, relishing the feeling. Celestia's facade cracked, just a little. Her cheeks seemed to glow red now, and her eyes were half-closed, her lips curled in a half-smile.

The time seemed to have come, and if it hadn't, Redheart was probably going to fail - she could feel her pleasure becoming nearly irresistible. She took a deep breath, and unleashed her best. Relaxing her throat, she took Celestia's long shaft to the hilt, her lips pressing against heavy alabaster balls like a kiss.

The final throw worked. She felt the balls clench against her lips, heard Celestia's surprised warning moan. She felt the heavy blast of liquid moving through the shaft as she pulled her lips back, and the first large burst surged between her lips to her eager tongue. It was warm, nearly hot, rich in a taste she adored but couldn't identify, and slightly spicy. She almost lost track of the danger, the sheer size of the load she knew was coming, and eagerly swallowed the second burst as well. Celestia pulled back against her eager lips, and that brought her to her senses. She cleared the tip just in time for the next burst to streak her lips and cheeks. It was deliciously warm, just on the comfortable side of hot, like being the perfect distance from a roaring fire. She lay back slightly and pushed the shaft slightly down, letting the rest of the massive load empty on her breasts and stomach. Each burst was like a ray of welcome sunlight falling on her flesh, but much though she was sure she'd love to watch, her eyes instead locked with Luna's, which seemed to have swelled massively at the sight of her sister unloading on Redheart's pristine flesh. Luna gasped, and Redheart closed her eyes as she felt her own resistance finally fall. Legs trembling she fell heavily on Luna's rock-hard shaft, taking it deep inside her. Even as she felt the last bursts of Celestia's cum splattering her chest, the first long rope of Luna's surged into her.

Like the sisters, the two were utterly different, but undeniably wonderful. Where Celestia's seed was like lines of liquid sunlight on her snow-white flesh, Luna's was the cool breeze of a summer night under the stars. While the pleasure Redheart felt in what was rapidly becoming the finest orgasm of her life thus far didn't fade, she found the coolness seeping into her core let her savor it. Her rational mind's detached view became both more and less distant, the pleasure seeping in but not controlling it, like the memory of joys long passed and fondly missed. She saw stars, but not spinning drunkenly before her eyes, but the calm vast galaxy looming overhead, full of secrets that promised only joy, not terror.

But this did not override the delicious, carnal knowledge that an unbearably sexy body was pumping sexual fluids into hers, in massive quantities. She felt the fluid swelling her vaginal canal, knew it was too much, that soon it would spread her wider as it flowed out of her around Luna's cock, drenching them both. But it didn't. Instead her cervix opened for it, not painfully, violently, as she knew could happen when a woman took on something too large for her. But rather she felt it open like a gate, letting in welcome visitors.

And in they came, in massive numbers. The night river of Luna's cum flooded into her, filling her whole body with the delicious coolness, save for the streaks of sunny warmth where Celestia's cum dripped on her body. She felt herself swelling with it, and it was too much. Her eyes stopped working. Her mind flooded with a starry sky, and she felt as if she were reliving all the best sensual moments of her life, from her first orgasm (under her own hands, usenet erotica on a two-tone screen) to the best ice cream she'd ever had. She probably blacked out.

She shook it off a moment later, and gathered herself. Her pussy was empty, but her belly was full. She lay on the floor of the sisters' living room, breathing heavily. Her body was streaked with Celestia's cum, and she did a double-take: rather than the white fluid she'd expected, nearly invisible against her own pure white skin, the streaks of fluid swirled like liquid rainbow, ever-shifting. Eyes wide, she looked lower. Luna's seed was dripping out of her in the form of the cosmos - an ink-black liquid swirling with stars and nebulae.

She remembered what she'd seen under her microscope, and mentally shrugged. Clearly the potions kept their strange effects, but even though her body, filled with cool and streaked with fire still, felt somehow fertile in a way it never had before, she knew the potion's own contraceptive spells would be in full effect. And this didn't even need a microscope to look nothing like human semen.

Besides, the sight of her belly swollen with Luna's cum, the feel and sight of Celestia's hot streaks all over her, left her feeling no less horny than she had before she'd brought up the subject of the potion. She looked around. Luna was lying back on the couch, eyes closed, breathing heavily, fluid-drenched cock intact. Celestia also seemed overcome - she lay not far from Redheart, serene but apparently stunned, her shaft too still rampant.

They did say it usually lasted for two loads, she thought. Well, good. I'm certainly eager for more. She was gripped with the desire to get both of the sisters' cum in her already swollen belly, to feel what night and day felt like mixing in her womb. She crawled over to Celestia and lay atop her, letting her own cum drip down on to her full breasts. She licked it off, savoring again the taste of unidentifiable spice. Celestia stirred beneath her. She slid her pussy, dripping her own hot fluids and Luna's cool, down to the other woman's wonderful shaft. She slid over it. Celestia's eyes opened and widened. Redheart pressed her ass back in one smooth stroke, spearing her eager pussy fully.

And fully it was. She felt Celestia fill her entirely, a long ray of glorious warmth that kissed, oh so gently, the gate that recently had admitted Luna's gift. She hoped it would be as willing to take her sister's, as she intended Celestia to be as deep as possible when she unloaded her second load.

Celestia seemed to have been about to say something, because her lips parted, but as Redheart's damp lips teased her still-full balls, she seemed to lose it, and instead a deep sigh issued. Redheart leaned down and kissed her, open mouth to open mouth. For a moment Celestia seemed stunned, then her tongue reached out, and danced with Redheart's as the younger woman rode her eagerly.

Finally Redheart broke the kiss, and moved her lips down, gulping down more of the delicious cum that had dripped on to Celestia's body.

"It looks like Luna likes your ass as much as the students do," Celestia said finally, and Redheart realized it was the first profanity she'd ever heard her use. She looked back at Luna, who's eyes were now wide and open, and did indeed seem to be fixed on Redheart's full white rear bouncing on her sister. She was lightly stroking her hard member, and from the easy way her hand moved, Redheart could tell it was still covered in a variety of lubricants.

"Don't just look," she said, and reached back to spread her cheeks even wider, "come fuck it." She wiggled for emphasis, and Celestia gasped at the sensation her pussy created as she did.

Luna gulped and licked her lips again, then nodded. She stood and strode over, then fell to her knees and pressed the tip gently against Redheart's pucker. Soaked as it was, it slipped in easily, but still she went slowly, careful of causing pain.

That wouldn't do. Redheart bucked up against her, leaving only Celestia's tip inside her and sinking Luna fully inside. Both sisters gasped in pleasure, and she reached back and grabbed Luna's hand, pulling her forward and keeping rear stuffed even as she fell on Celestia. She knew her orgasm was coming fast. The feeling of both sisters inside her at once was nearly unbearable in the pure physical pleasure it gave her. Luna remained cool, clear, and focusing, leaving her aware of the pleasure in a way she'd never been before, but Celestia was the warmth she loved about having a dick inside her but in perfect form. She knew her body would give in, and soon.

But what she craved was not just a normal orgasm, perfect though she had no doubt this one would be. She wanted again that feeling of enlightenment she'd felt when Luna unloaded into her, craved to know what she would experience when both sisters inseminated her at once, when their seed mingled in her womb.

And so she rode them as hard as she could, and they didn't seem to mind. At frantic pace she drove her body up and down, back and forward, both sisters sinking and rising in and out of her eager orifices. Every inch of her flesh was soaked - with the sweat and pussy juice of three women, and with Celestia's incredible prismatic cum. But still she craved it inside her. She wanted it deep in her being. Just the thought of it made her orgasm crash over her, but that only drove her harder. She screamed and kissed Celestia wildly. She reached behind her and stroked Luna's balls. She broke the kiss and howled, "give it to me!"

And they did. First Luna's river of night surged into her bowels. Medically, she knew she had no nerves there. She knew the human digestive tract was incredibly long, and it took hours for anything to work its way through the whole thing.

None of that mattered. She felt Luna's cum surging into her, night rolling in suddenly and in quantity as if she'd just turned off a camping light. It filled her with that same clear calm overlaid on her now multi-orgasmic frenzy. And she felt Celestia's cum, ejaculated into her mouth and eagerly lapped off her lover's full breasts, moving down through her innards to meet it, fire and water, night and day, rushing to meet inside her, in the place where her body made things its own.

Just before they did, Celestia exploded into her womb. Her cervix didn't even bother. The first jet of solar warmth passed right through joyfully, welcomed, leaving her nerve-rich vaginal walls painted in the warmth of a sunbeam. It eagerly surged to meet Luna's seed in the place where her body wanted to form new life.

They met at the same time. She felt fuller and fuller as the sisters pumped their magically full balls into her eager body, eager to find its capacity. She felt nameless things fill her mind. Equations and concepts she'd never seen and didn't understand, mixed with vast shapes of dark and light and a feeling of incomprehensible mass, but somehow she felt she knew them all, and was not afraid. Light filled her eyes even as they were closed, and she opened them to realize in pleasure-dulled calmness that it was because her entire body was glowing. Her breasts and belly were swollen as if pregnant, and all her white flesh had vanished, replaces with swirling, glowing patterns. Rainbows, pure warm splotches of sunlight, and deep pools of night danced on her flesh. She knew the secrets of the universe, though not in a way she could put in to words. She thought, though, she could sing them, and opened her mouth wide in joy. Three notes escaped, perfect and clear and ringing with the truth of the cosmos. Then she passed out, still quaking in orgasm.

"Oh dear," Celestia said, falling heavily again to rest against the couch. Though the cock was gone, and with it the overwhelming need to breed, she was now bone-tired, and still damnably horny. "I think that was a mistake."

Redheart no longer swirled with cosmic light, but her body still shook in orgasm, even though she was unconscious. Celestia thought it seemed to be fading, though. But she still glowed slightly, and despite her obscenely large belly, only her own clear fluids dripped from her naked pussy. Her body seemed unwilling to let a single drop of heavenly seed escape.

"You think?" Luna said. "Why didn't you stop her when she started fucking you? At least when it was just mine in there, it was coming out!"

"Why did you fill up her ass? At least if it's in her womb, her body won't try to metabolize it!"

At that, Redheart's orgasms finally stopped, and she settled, breathing easily and calmly. As the sisters watched, her belly began to shrink, though still no fluids emerged that might indicate why this was.

"You were saying?" Celestia grimaced.

"Shit," Luna sad. "Well, I guess at least we won't have a new baby demigod running around."

"No, but for all we know we might have an adult one. You know as well as I do about anti-entropy. If she's taking all that power into her body...It was just never a possibility for us before," Celestia sighed. "You know as well as I do mortal seed in us is no concern." She grinned. "Not like I don't remember the times we both knew it at once, for that matter. But this..."

"We should have known as soon as we saw how yours looked," Luna nodded back. "We should have stopped right then." She moved to kneel by their insensate lover.

"Could you even have stopped?"

"If I weren't already inside her, maybe. Maybe. I've never been so horny in my life as I was once I was inside her."

Celestia sighed. "Nor I. Maybe it's a sign this was meant to be, and will all turn out for the best. How is she?"

Luna pressed her ear to Redheart's gently heaving breast. A swirl of midnight light surrounded it briefly.

"Well, she's dreaming Deep Thoughts not even I can really decipher, so there's that. Though I think she can't either. But her body seems fine, as far as I can tell. She's not in a coma, it's not that kind of dream. She should wake up this morning, maybe early afternoon."

"Will she remember what happened?"

"Probably."

"Shit. Think we can play it off as 'those crazy potions, who knows what they do'?"

Luna shrugged. "Unless we think of something better before then, probably our best bet. I don't really want to tell her everything unless we really need to."

Celestia nodded. "I'll put her in the guest room, then."

She came back wearing a robe, and threw another to Luna.

"It was certainly nice, though," she grinned.

Luna grinned back. "I don't think I've had it that good since they had those fertility cults."

Celestia chuckled. "Maybe not even then. The penis is certainly novel. And she was so eager! It really has all been downhill since monotheism."

Luna sighed. "Yeah, but it didn't satisfy my pussy. I'm still dripping."

"Me too."

"I've got more potion..."

Celestia couldn't hide her reaction. "Are you sure your head has cleared? I don't want to think about what pumping your power directly into my body might do, or vice versa." She blushed. "Well, it would feel nice, I'm sure, but there's no way we can risk it."

Luna sighed. "You're right, of course, but I really want something inside me. Vibrator it is, I guess. Want me to bring one for you?"

"It just isn't the same," Celestia sighed. "But I suppose."

Just as Luna rose, though, the doorbell rang, despite the fact that it was now getting on towards ten, and even the summer twilight had faded into full night.

"Who could that be?" Celestia mused, rising to go to the door.

"You're going to answer in your robe?"

"At this time of night, any caller should expect it," she shrugged. "Besides, it covers everything." She opened the door, and was surprised to see Pinkie Pie standing in the pool of light that spilled out. Their recently former student's eyes were downcast, but based on her recent experiences, Celestia couldn't help but notice her skirt was very short, and her generous breasts were nearly spilling out of a very low-cut top.

"Hey vi, err, Celestia," Pinkie said. "I kind of have a problem, I hope you can help. Can I come in?"

"You realize I'm not your vice-principal anymore, right?"

"I know! But that's why I think you can help! It's really important to me."

Celestia shrugged. "Very well. I hope I can help. Luna, Pinkie's here to talk," she called out to her sister, hoping Luna had not made herself indecent.

She hadn't, and they found her sitting demurely, if only in her robe, on the couch. The room still smelled slightly of sex, but Celestia hoped Pinkie wouldn't notice.

"Now then dear, what can we do for you?" Luna said.

"Well," Pinkie seemed far more hesitant than usual, "you know basically everything that happens at the school, right?"

Both sisters nodded. "We try."

"So you know about my motto?"

"What happens in Pinkie stays in Pinkie?"

Pinkie grinned and nodded. "Right! And you know about Sunset's potion?"

They both nodded.

"Well, so when I found out about it, it was great! At first I thought I'd only be able to have sex with all the boys and gay girls before I left school. But then it turned out I had a way I could make the straight girls happy too! Either they could happen in me, or I could happen in them! The motto works both ways, you know. And I did it! Before graduation, I had sex with the whole class!"

"Did you get pregnant, Pinkie? We'll help if we can," Luna said.

"No, silly! I'm super careful about that. No, it's just, when I graduated, I realized something that made me super upset."

The sisters looked at each other in confusion. "And what would that be?" Celestia said.

"I realized I hadn't had sex with everyone who helped make my time at Canterlot High the very bestest! I still hadn't shown the teachers how much I appreciated them! Or, well, you two. So uh, now that I graduated and it's okay, I wanted to go around and give you all the chance to happen in me! Or for me to happen in you." She pulled out some bottles. "I bought some potions in case. Please can I fuck you?"

"Pinkie," Celestia said, though she certainly liked the thought, "we're a lot older than you..."

"You're still super hot though! And I'm legal! Like, even on the Internet! And it's not like I don't know what I'm getting into. Or into me."

"That is true," Luna said. "The whole senior class?"

Pinkie grinned and nodded enthusiastically. It did excellent things to her breasts. "Yep! Pleeeeease?"

"I was about to go get my vibrator...." Luna said, slowly.

"Say no more!" Pinkie uncorked one of the bottles and downed it immediately. She was wearing no panties under her short skirt, which was immediately obvious when a large pink shaft emerged from beneath it without even token interference.

"We're really doing this?" Celestia sighed.

"I am," Luna let her robe fall aside, "you can go to bed if you like."

Celestia didn't.

Author's Note

I couldn't work it into the story without a "of course you know, but", so I didn't make it fully explicit, but yes, Celesita and Luna are night and day demigods here, in case that wasn't as clear as I thought. Why they have day jobs as vice-principals is left as an exercise to the reader.