Celestia dipped below a cloud, then beat her wings, struggling to regain the altitude she lost. Her wings were powerful - as were Luna's - but they were rarely utilized for speed or for great distances. Not since Equestria's untamed days had the Princesses had to fly so far, so fast, under their own power.

When the princesses landed on the crystal castle's wide balcony, the saluting crystal guards saw the royal sisters slump to the ground, their sore wings quivering, their chests rising and falling with heavy, desperate breaths. They rushed to the aid of the collapsed sovereigns, examining them for any injury or sickness - but they seemed to be suffering from nothing more than extreme fatigue, and so the guards simply sent for water and food.

Chaise lounges were shoved into the receiving room, and Luna and Celestia allowed themselves to be levitated onto them. Once they had caught their breath and taken long gulps of water, they insisted upon meeting Princess Cadance, citing a matter of national emergency.

Cadance, of course, had already been apprised of the unscheduled arrival of two fellow princesses - and of their state of extreme exhaustion and distress. With no other matters occupying her immediate attention, she was already on her way, and she opened the door to the receiving room as Celestia and Luna were replenishing their energy with oats and sliced apples.

"Princess Celestia!" said Cadance, nuzzling her face comfortingly. "What's wrong? Are you all right?"

"No," said Celestia. "To be honest, Cadance, we are all in grave danger. Canterlot... has fallen."

"It can't possibly..." Cadance shook her head. "Should we dismiss the guards before we discuss it further?"

"This will be the Crystal Empire's concern as well," said Celestia. "Quite soon, I would guess. I see no reason to send them away."

"All right," said Cadance. "Given the seriousness of the situation, I hope you won't be offended if I confirm your identities..." Her horn shone with a rosy glow.

"Not at all," said Luna. "I would expect nothing less - although changelings are not the threat we face this day." Cadance fired a beam from her horn, first at Luna, then at Celestia - and to her relief, her magic did not reveal them to be changelings.

"Well then," said Cadance, "If you're comfortable here, please tell me what's going on. And... please tell me that Shiny is..."

"Unharmed," said Luna, "But greatly imperiled."

"We should start at the beginning," said Celestia. "Have you heard of the sirens?"

"I don't believe so," said Cadance. She wanted to stamp her hoof and demand to know what had happened to Shining Armor, but she held her tongue, awaiting the full story.

"They are dangerous creatures from the time of Starswirl the Bearded," said Celestia. "They had the power to control the minds of ponies with their magical voices. Starswirl banished them to another world through the magic mirror."

"The same magic mirror that Twilight Sparkle passed through once before," said Luna, "And from which she has not returned."

"It seems that the sirens emerged as a threat to Twilight's friends on the other side of the mirror," said Celestia, "And she went to help fight them. We do not know what happened to Twilight, but we must fear the worst, because the sirens have returned to our world. Not through the mirror, but through some other means... and with much more power than they had before."

"Their mere presence is enough to command the minds of most ponies," said Luna. "Their bodies are enormous, and they would only need to stand beside the Crystal Empire to enthrall its entire population... minus, perhaps, ourselves. They will be completely under the control of the sirens, all their loyalties forgotten."

"So... Shining Armor..." said Cadance, her voice quavering.

"Shining Armor is under their control," said Celestia, bowing her head, "And we need your help to free him."

Cadance ground her hoof against the crystal floor. "Not again," she said. "Why is he always being taken from me..."

"We can get him back," said Celestia. "But we must be ready. The three of us are the only ones we know will have the power to resist the sirens. We cannot rely on anypony else, and we must expect that anypony who comes within range will be turned against us."

"And our resistance against their power is not absolute," said Luna. "Speaking for myself, I can feel their power in the back of my mind, like an insidious whisper. All from, perhaps, a minute of exposure to their influence."

Celestia sighed and pulled herself up from the chaise lounge. "I can attest that I am also affected. If possible, it would be best to fight them from as great a distance as possible, so as to minimize their effect on us."

"How long do we have before they arrive?" asked Cadance.

"Hours, perhaps," said Celestia. "They have long strides, but they were not in a hurry to follow us. For now, we can rest... and watch the southern border."

"Are you certain they're coming?" asked Cadance. She levitated a large, pink mug of coffee to her mouth and took a deep sip. She wasn't sleepy - it was still midday - and, in fact, the caffeine was doing no favors for her addled nerves. But just looking out a window felt too much like doing nothing. Drinking coffee, at least, felt like she was preparing herself. Staying alert. It wasn't... nothing.

"No," said Celestia. Like Luna, she was lying down, still resting from the arduous flight. "Coming for us would be the most logical course of action, and it would be consistent with their attack on Canterlot, but I am not certain of anything." Cadance nodded, but didn't turn her eyes away from the window.

"They saw us flee northward," said Luna, "And if they spoke to Shining Armor, they could easily learn that we would retreat to the Crystal Empire. He was present at our strategy meetings, and while he is under their control, he would tell the sirens anything they wished to know-"

Cadance's aura flickered, and the coffee mug fell a foot and a half, tumbling and spilling its contents, before Cadance caught it again. Her aura enveloped the falling liquid as well, and without turning away from the window, she levitated the coffee upward, poured it back into the mug, and took another long sip.

"...I am sorry," said Luna.

"Aria, my goddess," said Shining Armor, "I beg you, if there is any way for me to serve you, you only need to say the word..."

"Ugghhh, you are smothering me!" groaned Aria Blaze. She held Shining Armor in clenched fingers, and she tightened her hand in annoyance, making the unicorn wheeze. "Oh, there's an idea," said Aria. "Adagio, can I smother him?"

"I would be honored-" gasped Shining Armor, before Aria squeezed him even harder.

"No," said Adagio. She peered forward, into the increasingly frozen north. They'd been following the train tracks (and occasionally destroying segments of track, as their whims dictated), and according to Shining Armor, the cold weather signaled that the Crystal Empire was close. "Believe me, I'd love to shut him up, but he made a pretty strong case that he could be useful. You know, to, uh..."

"You can use my subservience as a form of psychological warfare against my wife, Princess Cadance," wheezed Shining Armor. "When she sees that I love only you, it will... weaken her resolve..."

"Yeah, that," said Adagio.

"Plus, he could make a purple shield for you!" said Sonata. "Like around the city!"

"Actually," said Shining Armor, his voice weak and rasping, "That shield relied on... leylines... magical generators throughout Canterlot... A shield I created for you would be... smaller... unlikely to stand up against a sustained assault by alicorn magic..." He drew a few labored breaths into his constricted chest cavity before continuing. "Also... bruised ribs will... make it difficult to... cast spells at full power..."

"Are you criticizing my decision to injure your body?"

"No, my goddess," said Shining Armor. "Mistress Adagio requested brutally honest tactical advice. Just... doing my best..."

"Yeah, go easy on him," said Adagio. "For now. Like what I'm doing with Flitter, and what Sonata's doing with her little unicorn."

"Pfft," Aria spat. "I can't believe you're actually keeping your promise to that little pegasus. Dug her out of the dungeon and everything."

"Only for now," said Adagio. "Hey Flitter, whenever I feel like it, I might abandon you or crush you under my bootheel. How do you feel about that?"

"That sounds wonderful!" said Flitter, popping up from inside Adagio's hair. "If my sorrow or death can bring you even a moment of pleasure-"

"Yeah, yeah," said Aria. "Hey Sonata, didn't you leave that green unicorn behind in Ponyville?"

"I hijacked the train!" yelled Lyra, from inside Sonata's top.

"Yeah, she just showed up while we were smashing Canterlot!" said Sonata. "So cute!" Lyra, pinned against Sonata's nipple, spasmed in climax. Even the smallest morsel of praise from Sonata seemed to trigger an orgasm from her.

"So we all have our little pets," said Adagio. "Plus all the ponies rattling around in that tower." She looked over at the tower that Sonata was carrying - she'd snapped it off of Canterlot Castle and loaded it with volunteers before they left, and brought it along, in order to have some ponies to use as cannon fodder, or a distraction.

At least, that's what Adagio thought it would be good for. Sonata seemed to have different ideas. "Sonata," said Adagio, "There are some ponies left in that tower, right? You haven't been snacking on them too much?"

Sonata didn't respond right away, but instead swallowed, and a lump that looked suspiciously like two copulating ponies slid down her throat. "No," she said innocently. "And even if I was, I have to keep my strength up! We're walking into the arctic north!"

"We were just fine when we were standing in outer space," said Aria. "I think we can handle a blizzard."

Beyond the range of the Crystal Heart's aura, visibility was low. The Heart kept out the north's eternal winter, but outside its radius the whipping winds and dancing snow hid the world behind a white veil. By the time the sirens came within sight, they would be very near to the city. It would be little warning, but it would have to be enough.

There was an instant where she wasn't sure she was seeing anything - perhaps staring into an endless plane of white was making her eyes play tricks on her - but the more she watched, the clearer it was. Three hundred-foot-tall young women, their bodies and clothes brightly colored, were making their way towards the Crystal Empire.

"They're here!" cried Cadance, and Celestia and Luna sprang from their seats.

"We are clear on the plan?" said Luna. "Minimize contact and strike together at the nearest target. If we can take down one of them, we can expect their power to weaken."

Cadance leapt through the window and spread her wings, followed by Celestia and Luna. Celestia took the lead, and her horn glowed, building power. Cadance focused power in her horn as well, letting all the magical power in her body pool at its tip. Once the princesses joined their power for a single deadly strike, there would be very little magic left in them - but weakening the sirens would be worth it.

"Luna?" asked Cadance, "Uh, you'll need to be ready to strike soon..."

Luna shook her head and made a confused sound. "Uh? Yes, of course, of course." Her horn, previously unlit, began to glow. Cadance knit her brow in concern; was Luna merely tired? Distracted? Or was the power of the sirens doing its work on her?

Cadance felt her heart sink as she contemplated the sirens' mental influence. Mind control had been a consistent feature of Cadance's nightmares since the day of her wedding. Typically those troubling dreams featured Chrysalis, her body huge and full of enormous, seeping holes, somehow taking Shining Armor from her. Sometimes she was holding him, sometimes mating with him, sometimes consuming him. Sometimes Chrysalis was taking other people from her - her family, her kingdom - but Cadance rarely considered what would happen if her own mind was enthralled.

But now the problem was immediate. As they approached the edge of the kindgom, they came closer and closer to the radius of the sirens' subtle power. Cadance didn't know what it would feel like to have that power touch her mind; she'd asked Shining Armor all about what he went through, but she suspected that there was no way to truly understand what it was like.

"Merge," ordered Celestia, and the magic in her horn flowed upward like smoke, coalescing into a sphere over her head. Cadance and Luna both focused their power into the sphere, making it grow and swim with color. Celestia would hold the magic as long as she could, and then fire at the nearest siren... which looked to be the purple one...

"Ooh, it's the welcome wagon!" said Aria, stepping out ahead of her friends. She peered across the flat plain, through the whipping blizzard. They were close to the Crystal Heart's radius, and there was a clear line where snow gave way to mild temperatures and verdant spring. "Hm, looks like they're keeping their distance. Smart. Sonata, can you, uh, do the thing? So they can hear us?"

"Opening hailing frequencies!" said Sonata. She hummed, using the magic of her voice to manipulate the air between the sirens and the alicorns - and then her voice came across loud and clear to the princesses.

"Hey, look!" said Aria, calling out to the distant princesses, who were holding steady in midair, "The ponies built us another city to smash! Ooh, and the buildings are all made of rough angles... I like it! Ever since my pussy became indestructible, it takes some serious roughness to really punish my cunt. You girls know what I mean, right?"

The princesses didn't respond - they just kept focusing their power, building the sphere over Celestia's horn bigger and bigger.

"Okay," said Aria, "the white one is Celestia, the blue one is Luna... Shiny, I'm guessing the tasteless pink one is your wife?"

"Yes, my goddess," said Shining Armor, still grasped in Aria's fingers, "But all my bonds, all my loves, are dissolved, save for my love of the beautiful and mighty sirens."

"I'm not sure she heard that," said Aria. "Hey Princess Cadance!" called Aria, "Your husband says he doesn't love you!"

"Ignore them, Cadance!" said Celestia. "We will free him from their power once we strike them down!"

"Why wait?" said Aria. "I'll free him right now!" She raised her free hand high in the air and snapped her fingers. In her hand, Shining Armor blinked and shook his head.

"Cadance!" he yelled, "I love you! You... you can't let the sirens win! Please, even if it means killing me, you have to hit them with all you've got!"

"You head the stallion," said Aria. "Go ahead and fire off your Neapolitan Swirl Princess Beam! Just be careful that you don't hit me here..." She held Shining Armor in front of her face, "...or here..." She held him at chest level, over her heart, "...or here... She held her hand over her crotch, gently rubbing herself with the hand that held Shining Armor. Cadance, tears welling in her eyes, felt her horn flickering as her focus eroded.

"Cadance, you have to trust me," said Celestia. "I will be aiming the beam, and I will not allow Shining Armor to come to harm. The movements of her arm are not abnormally fast; I can easily aim at an unprotected spot."

Cadance drew in a deep breath. "I trust you, Celestia." She raised her head, looking sternly at Aria, and her horn glowed with rosy energy.

"Ooh, I was expecting that to work better," said Aria, smirking. "Well, since you surprised me, here's a surprise for you! I didn't free Shining Armor from my mind control. I don't-" she interrupted herself with a disdainful chuckle, "I don't even know if I could!"

"You're disgusting to me, Cadance," said Shining Armor, his voice rich with sincere malice. "Anyone who opposes the omnipotent sirens is hateful. Wretched."

"He was just acting!" said Sonata. "We worked it out beforehand!"

"Honestly," said Adagio, "You might never get your husband back. Our control is so powerful, so deep, that even if you killed us, you might just end up with an empty husk. Or a stallion who eternally hates you for killing his beloved goddesses." She chuckled. "And the same would happen to everyone in Ponyville and Canterlot! A whole kingdom of vegetables, or of ponies who hate you forever..."

"Sounds like a real hassle," said Sonata. "If I were you, I'd just give up!"

Adagio looked over at the princesses, past the edge of the Crystal Heart's radius, trying to discern their reaction. Cadance's face was still steely; it seemed like their words weren't having much effect. If Adagio Dazzle knew about Cadance and Shining Armor's history with mind control, she might have guessed that Cadance, in spite of her fears, had mentally prepared herself for a day like this. If Adagio had known much of anything about love, she might have supposed that Cadance's love for Shining Armor - and for the crystal ponies whose lives depended on her actions - were giving her the strength to do what needed to be done.

But she would have come to the same conclusion regardless. "Sonata," she said, "It looks like they're going to shoot us. Can you shake that tower a little?"

Sonata lifted the tower she'd snapped off from Canterlot Castle and shook it, rattling loose a few dozen pegasi. "Okay, thralls," said Adagio, "I seem to remember that princesses don't like hurting innocent ponies. Why don't you make this shot... a little more challenging."

The pegasi swarmed in front of the sirens, forming a cloud in front of the sirens. "Yes, perfect," said Adagio. "And if the princesses fire some sort of alicorn laser at us, make sure to throw yourselves into it."

"Sister..." said Luna, her voice wavering.

Celestia growled through her teeth. "We can't..."

"Celestia? Luna?" said Cadance, "What's the plan?"

"The sirens are a threat to all of Equestria," said Luna. "Some losses would be acceptable."

"It has been centuries since I have taken a life," said Celestia, "And magic of this power and complexity takes absolute focus. If I attack, knowing that my magic will end the lives of innocent ponies... I am certain the spell would misfire. The power would become diffused - it would not be strong enough to affect the sirens, but it would still kill the pegasi. And it would leave us drained, defenseless as the sirens took the Crystal Empire."

"So we retreat?" asked Luna.

"Yes," said Celestia. From the sphere of swirling magic above her horn, two strands of energy stretched out to Luna and Cadance, returning their power to them. "We retreat to the castle and devise a new plan."

"Aw, that's no fun!" said Sonata. She flipped up her skirt and framed her pussy lips with two fingers in a V shape. "If you come over and let us dominate you, you can all have a princess party in my pussy! I promise it'll be the time of your lives!"

Cadance felt her mouth water, watching juice drip from Sonata's giant blue pussy. She realized then that she was already being affected by the sirens' magic - even at this distance, it was starting to creep into her mind. It was clawing, insistent - and yet comforting. She knew that if she let herself give in to it, she would be happy - blissfully happy to serve the sirens in any way they desired, whether through backbreaking labor, sexual service, or merely as a victim for their violent whims. With her mind under their control, her life would have purpose, she would never doubt or fear, and the loss of her husband's love would never trouble her again.

"Come on, join the fun!" said Sonata. She lowered the tower to her crotch and held the rounded tip against her lips, teasing her pussy with its tip. "Hey!" she said, "Any unicorns left in there? How about you shake things up?" The tower was surrounded by a multicolored aura, made up of the combined efforts of the unicorns within. The tower started to shake - or rather, to vibrate - and Sonata held it against her clit, changing up the angle as she stood on quivering knees.

"To the castle," said Celestia, swooping down and turning back towards the city. Luna followed, and Cadance, shaking her head to clear away the sirens' power, flew after them.

"Aw, I was really hoping they'd get in on this," said Sonata. She dug the tip of the vibrating tower into her pussy, working it between her folds and dripping juices down its length. She drew in deep gasps as she worked herself over, and Adagio turned her eyes away from the fleeing princesses, toward her masturbating friend.

"All right, I'm taking over," said Adagio. She reached down and grabbed the base of the vibrating tower, and Sonata released her grip on it. "Good," said Adagio, "Can't have my underlings thinking they know how to make themselves cum. You wanna cum, you leave it to me."

"Mmm, yeah," said Sonata, as Adagio circled her clit with the tip of the buzzing tower, "You're the boss, Adagio..."

"Hell yes I am," said Adagio. "That sweet blue cunt... those gorgeous tits... all mine." She sank the tower deeper into Sonata's folds, keeping the shaft up against her clit, and leaned in for a kiss. Sonata met Adagio's lips with her own, tasting her friend's mouth with deep explorations of her tongue. Adagio meshed her fingers with the hair on the back of Sonata's neck, pulling her deeper into the kiss. Sonata slumped forward, almost melting into Adagio, holding herself upright with one hand on Adagio's shoulder while the other one massaged her friend's breast. She clung to Adagio, clutching tight to her shoulder as her knees wobbled beneath her and her pussy flowed with nectar.

Adagio angled the tower upwards, pressing it up against Sonata's clit. Sonata's body quaked, barely holding steady as her pussy shuddered toward climax. She was hanging from Adagio now, almost falling to her knees, her pussy pouring its juices onto the tower and the frozen ground below. Adagio cradled Sonata's head, keeping her locked into the kiss, devouring Sonata's moans as she orgasmed.

Adagio kept the buzzing tower against Sonata's clit, not letting up, determined to make her climax last as long as possible. Sonata's muffled moans became weaker and weaker, and the flow of juices across Adagio's fingers surged - then slowed. Adagio pulled the tower from Sonata's folds, and Sonata dropped to her knees, groaning.

"Well, that was cute," said Aria, "But if you girls are done, we should probably get moving. The Crystal Empire deserves a show..."

"Aw, someone's jealous," said Adagio. "Don't worry, I'll take care of your pussy soon enough."

Aria scoffed.

"So what's the plan now?" asked Cadance, touching down on the castle's balcony.

"Combining our magic for one full-force attack is still our only real option," said Celestia. "But we need a clean shot at one of them. No innocents in our way. Nothing to throw off our focus. And... I suspect it goes without saying... this is likely to be our last chance."

"The sirens' power gnaws at my mind," said Luna. "Stronger now than before. If we come near to them again, we may not come under their total control... but I suspect I will not have a strong enough will to fight against them."

"All right," said Cadance. "I think I can get us our clean shot."

"Hel-lo Crystal Empire!" said Adagio, strolling into the edge of the city and spreading her arms extravagantly. "Are you ready for a show?" The sirens' influence was wide enough that half the Empire was inside it, and the crystal ponies nearest the giantesses were fully enraptured. They poured out from their homes and businesses, their work forgotten as they rushed to cheer for their new goddesses.

"Well, too bad," said Aria. "We don't really do shows anymore. We just show up and enslave ponies' minds with our magnificent presence."

"I like singing," pouted Sonata.

"Well, yeah, me too," said Aria. "It's fun. But a public performance feels too much like we're doing them a favor, you know? It's like, we're in charge, why should we entertain them?"

"All right," said Adagio, "I like singing too, so let's all agree that, once we take over Equestria, we'll all sing together like we used to. But it'll be for us, right? And if any ponies happen to hear it and enjoy it, then that's, you know, whatever."

"Aww, you're the best, Adagio!" said Sonata. She threw her arms around Adagio and rubbed her cheek against hers. Adagio, in spite of herself, laughed and blushed.

"Geez, Sonata, not in front of the mindless thralls," said Adagio. An "awww," was rising from the crowd, like a sitcom audience reacting to a warm moment, but a halfhearted glare from Adagio shut them down.

"All right," said Adagio, shrugging her shoulders to throw off Sonata's hug, "I saw the princesses fly into the castle. Let's get nice and close to them, then let our aura do its work, okay?"

"Sounds good," said Aria. She raised her hand to her face, bringing Shining Armor to eye level. "Hey little guy, are the princesses going to be able to shield themselves against our power?"

"No," said Shining Armor, "That's why they have me. Had me. If they're holed up in the castle, your power should win them over in time."

"Okay, cool," said Aria.

"And by the way," said Shining Armor, "You're going to love having Cadance under your control. She's an adventurous, giving lover, and-"

"Ugh, gross," said Aria, "Don't make me think about her doing things with dudes."

"Sorry, my Goddess."

"All right," said Aria, "Let's get nice and close to that castle. Give the princesses a big dose of our magnificence." She walked over to the high crystalline castle, crushing buildings into crystal powder beneath her feet, feeling the love of the ponies beneath her flow into her body. The sirens all grew as their bodies absorbed the worship of the crystal ponies - their heads rose higher, making the imposing castle look more and more like a toy. Their boots grew wider, able to crush more buildings into dust with a single step. The densely populated city brought them nearly to a hundred and fifty feet in height, and their bodies buzzed with ecstasy as they expanded.

"Ooh, that's the stuff," said Adagio. "The human world was garbage, mostly... but it felt nice to be growing all the time."

Aria Blaze, standing beside the castle, leaned her body into the crystal structure. Her breasts were now large enough to embrace its tallest tower, and she squeezed the soft flesh of her tits into the hard crystal. "Oh princesses," she cooed, "Are you in there? Maybe you'd like to come out and soak in the beauty and power of the sirens?" She ground her hips into the base of the tower - then suddenly froze as she felt a hand on her ass.

"You didn't think I'd forgotten about you, did you?" said Adagio. She reached under Aria's skirt, put both hands on her ass, and kneaded the soft flesh gently. "I promised I'd get around to your pussy, didn't I? Can't let my second-best friend feel like she's being ignored..."

"Hm," muttered Aria, shifting her hips to better enjoy the massage Adagio was giving her, "You usually call me your 'worst friend,' Adagio."

"I'm in a good mood," said Adagio. She widened her stance, knocking crystal building aside as she shifted her feet, and brought the fingers of one hand around to Aria's pussy, separating the wet lips and nimbly exploring her friend's familiar folds. Aria groaned and leaned her body into the tower, making it bend slightly. "Sonata," said Adagio, "why don't you find a building for me to shove up into Aria's cunt? Something nice and rough to punish her pussy."

Sonata circled the castle, kicking crystal homes and stores into the air with great sweeps of her leg, breaking them off from their foundations and sending them flying with her enormous boots. After she'd knocked loose a few dozen, she squatted over the wreckage and inspected the scattered buildings. "Hmmm," she muttered, sifting through the rubble, "What's the perfect building to shove in Aria's pussy?" She picked up a crystal pony between two fingers, a little unicorn mare with shimmering pink skin and straight blue hair. "Hey cutie!" she said, "What building would you use? Aria likes it rough!"

"Uh, maybe Diamond Brush's house?" said the pony. Big green building over there -" she pointed with her hoof. "Still standing, pretty tall, pretty wide..."

"Thanks!" said Sonata, and tossed the helpful mare into her mouth. The little crystal pony bounced onto Sonata's tongue and lay there for a moment before Sonata swallowed her. "Mmm!" Sonata said, "Crystal ponies taste different! I like it!"

Instantly there were ponies gathered around her feet, and pegasi in the air, begging to be eaten. As she treaded over to the building the crystal mare had indicated, she opened her mouth and let the pegasi fly into it. Once there were ten or so in there, she closed her mouth and tasted the writhing, squirming mass of crystal ponies on her tongue. As she savored the morsel, she wrapped her hand around the green crystal house and wrenched it from its base.

"Got one, Sonata?" asked Adagio. "You know my fingers aren't gonna keep Aria's hungry cunt satisfied forever!"

"Yeah, I'm working on it," said Sonata. She picked up a green pony, then a yellow one, and popped them in her mouth together, her face showing a bit of disappointment when the crystal failed to produce a lemon-lime flavor on her tongue. "Gomma fime sumfin goob for Aria..."

"Just swallow those ponies and hand me any building," said Adagio. "I'm trying to get some sexual energy flowing here."

Sonata swallowed. "Okay, okay." She brought the building over to Adagio and placed it in her outstretched hand. Adagio tested the crystal house's weight in her hand, then brought its tip to Aria's lips.

"Here you go, Aria," she said, tracing the crystal structure along her friend's dripping folds, "Nice and big and rough for your indestructible pussy." She leaned her body in Aria's, pinning her against the crystal castle's highest tower. Cracks began to form along its base, sending powdered crystal drifting to the ground. Adagio reached around Aria's body and dug her fingers into Aria's tight purple top, groping her tit and kneading the soft flesh with her palm. "You want it, bitch?" she growled, grinding her crotch into Aria's ass. "Say you want it."

"You fuckin' know what I want," said Aria. "I gotta know that my worst friend Adagio is still a heartless bitch. You're letting ponies nest in your hair, you're letting Sonata hug you without calling her a moron... show me you can still be cruel."

With a single forceful motion, Adagio rammed the crystal building into Aria's cunt. Aria screamed, grabbing at a lower tower for balance, almost stumbling as it snapped off in her hand. "Yeah," Aria growled. "That's the good shit." She groaned and gasped as Adagio pushed the crystal deeper, her slumping, squirming body putting more and more weight on the crystal castle.

Sonata dropped onto her butt, cracking crystal buildings underneath her and making the rubble jump with the force of her big-assed impact. She set her eyes on her friends, watching Adagio grind her body against Aria, pinning her against the tower, groping her body and fucking her pussy. Sonata watched nectar drip down Adagio's legs as she bucked her hips against Aria's ass, and Sonata reached her hand down under her skirt, touching her lips with gentle fingers. Her other hand slipped underneath her deep purple top, letting her finger circle her nipple. Lyra, still stuffed down her top, picked up on the movement and heat of the giant human body she was pinned against - and she did the work of another set of fingers, grinding her tiny body against Sonata's fat blue nipple, stroking her hooves against the massive areola.

Sonata closed her eyes and raised her face to the sky, focusing on the feelings in her body and the sound of Aria's fevered moans. But a distraction brushed against her blissful reverie - a gentle dusting of snow on her face, a cold wind against her skin.

"Hey, is it getting cold?" she said, her fingers still working at her clit.

"Who cares?" says Adagio. Her arm, still groping Aria, held her friend steady "We walked through a blizzard. Our heads were in outer space. Don't whine about cold."

"No, I mean, it stopped being cold when we came into the city, but now it's - OW!" Sonata grabbed her shoulder and turned to her side, looking for the source of the sudden sharp pain. She thought she saw a splash of pink in the sky, but it quickly disappeared into the gathering snowstorm.

And the storm was gathering fast. Sonata didn't know about the Crystal Heart, but she knew that something must have been holding the frozen North at bay - and now, clearly, it wasn't. And the thick, zero-visibility blizzard was concealing Sonata's little pink attacker. A bolt of rose-colored energy shot out of the wintry void, striking Sonata in the cheek, and she sprang to her feet and swiped her hand in the direction the attack came from. But her hand just swung through the empty air.

"Hey! The princesses are back!" said Sonata. "And they're still no fun!"

"What? Come on, I'm in the middle of something," said Adagio, working the crystal building in and out of Aria's cunt. "Can you guys at least wait until I make Aria - FUCK!" A bolt of midnight-colored energy hit her in the back of the neck, and as she turned to look at the retreating black splotch in the sky, a luminous yellow bolt struck her in the temple. That time, when she turned to look at her attacker, she didn't catch so much as a glimpse of Celestia, whose pure white coat made her all but invisible in the snowstorm.

"Okay," said Adagio. "This is pretty clever, ponies. But here's what I think of your little bug-bite attacks. Pegasi! Swarm formation, around all of us." All over the city, crystal pegasi rose from the ground and swirled around the sirens. "I'm going to finish making Aria cum, and until then, I'm just going to ignore you."

Sonata opted not to ignore the princesses. She stomped blindly through the blizzard, swiping at the sky, catching the occasional magic bolt in the face and boobs. Regions of the Crystal Empire that had previously escaped destruction were crushed underfoot as Sonata stumbled about, her blind swipes only striking the occasional swirling pegasus - and scooping them up to pop into her mouth.

Adagio and Aria fared a little better, if only because Sonata was occupying most of the princesses' attention. Adagio, who had Aria pinned against the castle, was more exposed and caught more bolts in the back - but she kept at her work, thrusting the crystal structure in and out of Aria's dripping pussy, groping her tits and breathing hot, heavy breaths onto the back of her neck. Fewer shots hit Aria, but when they did strike her, they did little more than make her moan and cause her pussy to throb. "Mmm, harder," she groaned, quivering as each bolt made contact. "I'm so close..."

Adagio was almost as focused on Aria's climax as Aria was, and Sonata quickly reached the point where she was having loads of fun stomping around the city. And none of the sirens noticed two important things: firstly, that fewer and fewer magical bolts were striking them as time went on. And secondly, the swarms of pegasi around them were slowly dropping to the ground. In spite of their slavish devotion to the all-powerful sirens, the crystal ponies could only withstand so much cold, and their wings could only fight against the wind for so long. The sirens, aware of the cold but largely unaffected by it, didn't consider what it would do to their thralls.

And so, with the skies cleared of innocent ponies, the princesses once again joined their power, funneling it into a growing sphere above Celestia's horn. One of the sirens might have been able to spot the luminous sphere, had they known exactly where to look, but the storm made it all but invisible.

And the sirens, by contrast, were enormous targets decked out in vibrant colors. What's more, two of the sirens were standing still, locked in a sapphic embrace as Adagio groped and fucked Aria to climax. The princesses' power, joined together, could strike them both - likely demolishing the castle in the process - leaving only one siren surviving. The sphere over Celestia's horn approached critical mass - within seconds, it would explode if it were not fired at the sirens. Every ounce of focus - from all the princesses - would be required for this one final strike.

And the sound of a giantess-sized orgasm wouldn't normally have fractured the focus of the princesses - they were, after all, fighting for the freedom of all Equestria. But when Aria came, her cunt spasming and squirting around the impromptu dildo Adagio was using, her voice carried the power of the sirens at its most concentrated. The minds of the princesses reeled - not totally subsumed by the influence of the sirens, but suddenly awash in worshipful desires.

And none of them struggled more than Luna. Celestia was wise and ancient, her strength of will enforced by centuries of ruling Equestria. Cadance, while much younger, was respected and loved. But Luna had spent a lonely millennium in her lunar prison, and before that, she had stewed in bitterness for years, feeling utterly unloved. Even after her redemption, she had struggled to be accepted in modern Equestria, desperate to find her place in a world that only knew her as a nightmare. The world proposed by the sirens offered her everything she lacked - her mind would be reforged in love, blissfully happy to serve her goddesses. In the sirens' Equestria, Luna would always know her place in devotion and submission.

It wasn't enough to make Luna give in. But when she looked at the beautiful, towering bodies of the sirens, when she heard Aria Blaze calling out in orgasm, she couldn't bring herself to cause them harm. There had to be another way, surely...?

Panicking, unwilling to besmirch the perfect beauty of the sirens, Luna sent a jolt into the magical energy she was providing for Celestia. An ethereal whipcrack, a bit of spin, just enough to throw off the aim of their combined attack. Celestia felt the jolt, but it was too late to do anything about it - she had to either fire it off or let it explode over her head.

The beam, swirling with color and screaming with power, fired off in the direction of Aria and Adagio. But Luna's indecision twisted it just slightly - and that was enough to make it miss their bodies entirely. The beam singed the fringes of Aria's skirt and slammed into the ground, vaporizing crystal buildings and leaving line of smoking wreckage where it touched the earth.

The princesses stayed in place, flapping their wings, staring open-mouthed at the destruction they'd caused. Cadance had no idea what had happened. Luna felt her stomach sinking as she realized what she'd done. Celestia almost couldn't believe Luna's betrayal - but she had felt it, unmistakably, as she had fired the beam. Tears welling in her eyes, she turned to Luna, struggling to form the question "Why?"

But in that moment, all three of them were snatched up by enormous hands. Adagio's fingers closed around Celestia's body, Aria grabbed Luna, and Sonata snatched Cadance from the sky. "All right," said Adagio, "This has been adorable, but I think it's time to move our conquest forward. Girls? Let's sing."

The sirens joined in harmony, and as they sang, the alicorns in their hands struggled less and less. In time, they fell slack, their breathing calm and their heartbeats slow and even. At the close of their song, they could feel the absolute devotion of the three alicorns flowing into them, and their bodies tingled with growth.

"Well, that's Equestria conquered, pretty much," said Aria, stretching her expanding limbs. "Who's left? Dragons?"

"You will have our strength on your side, oh sirens, oh goddesses," said Luna.

"We will lead your subjects into battle against any who oppose you," Celestia agreed, nuzzling her face against the tip of Adagio's finger.

"Might be fun to watch that," said Adagio. "Probably not necessary, though? We'll let you send in a few battalions, watch 'em get roasted, then we'll step in and enthrall the dragons. Not to sound like a pussy, but now that we're in charge, I don't want my thralls just dying off all the time." Aria, hearing this, audibly groaned.

Cadance spoke up. "Then... my goddess, might I humbly suggest that you permit me to restore the Crystal Heart to its proper place in the castle? Without it, the population of the Crystal Empire will very shortly die of exposure."

"Yeah, I guess," said Adagio, rolling her eyes. "Sonata, let her go so she can do the thing with the, uh, whatever."

"Okay!" said Sonata. She opened her hand, letting Cadance fly back to the crystal castle. "Ooh, Aria, do you still have Shining Armor? When Cadance gets back, we can make them kiss!"

"Uh, no?" said Aria. "Cadance is cute, I don't want to think about her doing stuff with dudes. Besides, I probably crushed that guy at some-" she opened her palm and looked down at Shining Armor. "Oh, check it out! Still breathing and everything."

"Ooh, dibs!" said Sonata. She plucked Shining Armor from Aria's open palm and popped him into her mouth.

"Wait," said Adagio, "Didn't you just want to make him kiss Cadance or something?"

"I'm fickle," said Sonata. "'Tis the prerogative of a goddess."

Aria smiled. "That's the spirit."

The sirens shared a cruel laugh. Now the sun and moon rose at their command. Now love itself belonged to them. Equestria was theirs to conquer and reshape, and none remained who could stand against them.

Author's Note

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