A chill mist seeped into the very bones of ponies out and about in the streets of Ponyville. It was the middle of the morning on what should have been a clear, warm spring day, yet the haze and cold had discouraged many ponies from leaving their homes. A bitter wind blew through the foggy streets; those brave or unfortunate souls who found themselves outside wore thick woolen cloaks and unhappy expressions.

Princess Twilight Sparkle, wrapped in a warmth spell, rose above the mists, seeking out the weather team. Within minutes of piercing the foggy veil, she spotted the gleaming spectrum that was the wild mane of her good friend Rainbow Dash. The brash pegasus hovered above the fog with three other members of the weather team. Twilight adjusted her course and, with a determined beat of her powerful wings, shot toward the pegasi.

As she drew near, her ears picked up a heated conversation:

"—still can't figure out where it's coming from."

"We've gotta get rid of this fog, though!"

"What do you think we've been trying to do all morning?"

"Has our messenger come back from Cloudsdale yet?"

"Rainbow Dash!" Twilight called as she drew near. The pegasi turned; three of them dipped their heads in respect.

Rainbow sighed wearily. "Hey Twilight," she said. "I'm a little busy right now."

"I pretty much figured that out," Twilight said, frowning. "What's going on? Ponyville never has fog. And it's supposed to be 71.4 degrees right now!"

"I know," Rainbow groaned. "There's a cold wind coming from somewhere, but nopony seems to be able to figure out where, and I sure as hay didn't order this fog."

"We've been trying to clear the fog all morning, Your Highness," Thunderlane said. "It just...won't go away."

"And you have no idea where it came from? At all?" Twilight asked, tilting her head.

"Not a clue," Rainbow said. "It just showed up right around dawn."

Twilight frowned. "Hmm..."

Blossomforth's ears twitched. "Princess Twilight? Do you have some spell that can get rid of this fog?" she asked hopefully.

Twilight shook her head. "I'd rather not try casting random spells into a mysterious fog without studying it," she said. "But..." She trailed off. "I might have an idea."

"We're all ears," Rainbow said.

Twilight summoned a roll of parchment, a quill, and an inkpot out of thin air, and quickly wrote a note. "Rainbow Dash, how fast can you fly to Canterlot?"

Rainbow gave her an incredulous look. "Um, hello? Fastest flyer in all Equestria!"

Twilight rolled her eyes as she sealed the finished scroll, then banished her quill and ink. "I want you to take this to Princess Celestia," she said. "Tell her what's going on here and that I'm studying the fog itself. By the time you get there, I'll have enough samples of the fog collected to study it."

"Okay..." Rainbow said. "Why me, though? I mean, can't you have Spike send it, and it'd get there right away?"

"I need the time to gather fog samples," Twilight said. "Plus, I need you to tell Celestia exactly what's going on, and you're the weather expert here."

Rainbow nodded hesitantly. "Okay, that makes sense. But...what is it you think Princess Celestia can do about this fog that you can't?"

Twilight smiled. "She can burn it off with the sun."

The pegasi made an impressed sound of realization. "Yeah, I guess that'd work," Rainbow said. "Okay, I'm off. You three, keep a lookout for that messenger." With that, Rainbow disappeared, leaving a multihued contrail in her wake.

"Thank you so much, Your Highness," Blossomforth said.

"Don't thank me yet," Twilight said. "We still need to get to the bottom of this." With that, she descended into the fog.

It took Rainbow Dash seven minutes to reach Canterlot. Maintaining her speed until she reached the Palace, she landed heavily on the steps, panting for breath. Two alarmed Royal Guards closed ranks on her, faces stern.

"I have a message...for Princess Celestia...from Princess Twilight Sparkle," Rainbow gasped out between breaths. "It's urgent."

The guards looked at one another, then opened the great doors to the Palace. One of them called to a unicorn guard stationed inside, "This mare is a royal courier. Please escort her to the throne room at once."

Rainbow Dash trotted alongside the stone-faced, armored unicorn. It felt like a lifetime had passed when they stood before the great doors to the throne room. The guards stationed there saluted their comrade, giving Rainbow questioning looks before opening the doors. Heedless of the admonitions of the guards and the court herald, she took wing and flew straight for the throne, where Celestia sat engrossed in a book while sipping tea. "Princess Celestia!" she cried.

Celestia looked up, tilting her head. "Why, good morning, Rainbow Dash. What an unexpected pleasure it is to see you." She smiled. "What brings you all the way to Canterlot, my little pony?"

Rainbow brandished the scroll Twilight had given her. "Twilight sent me," she said. "We've got a real problem down in Ponyville and we need your help!"

Celestia blinked as she took the scroll with her magic. "A problem Twilight needs my help with? Why did she not send a message via Spike?" She gasped. "Has something happened to Spike?"

"No, Spike's fine. She just wanted me to deliver the message personally so I could explain," Rainbow said breathlessly. "Ponyville's covered in fog and we can't get rid of it. There's a cold wind coming from somewhere, and we can't figure out what's causing it. My team's still waiting to hear back from Cloudsdale. Twilight didn't want to try to clear the fog herself because she wants to study it first—that's part of why she sent me instead of using Spike. She's collecting samples of the fog."

Celestia frowned as she unrolled the scroll and read it. "Goodness...well, given Ponyville's proximity to the Everfree Forest, I'm not surprised an unusual weather event would intrude, but..."

"It's not coming from the Everfree," Rainbow said, shaking her head. "That's the first place I checked. Everything's quiet there. Well, as quiet as it ever is."

"Hmm," Celestia said, pursing her lips. "There are several things that could cause a fog pegasi can't dissipate, but none of the ones I can think of off the top of my head could be responsible. You say it isn't the Everfree Forest, I know it isn't Discord...it could be a malevolent unicorn, but Twilight would be able to detect that almost immediately..." She shook her head. "I'll have to consult my library about this. And, of course, I'll have to ask Twilight to send me her findings immediately." She rolled the scroll up; it disappeared in a flash. "As to her request..." She frowned pensively. "I can certainly use the sun to burn off the fog, even though I hate to tamper with the sun like that. It's...an inelegant solution."

Rainbow's ears drooped. "You mean you're not gonna help us?"

"I never said that, my little pony," Celestia said. "I will burn off the fog, but if it should return, it will be up to Twilight Sparkle—and her friends—to determine the source of the fog and find an appropriate way to eliminate it. I dare not risk abusing the sun in this manner more than once."

Rainbow let out a relieved sigh. "Thanks, Your Highness."

Celestia rose from her throne and strode down the length of the throne room, calling out to her guards and courtiers. "Please spread the word: anypony who is outside at this time should retreat indoors. I have a number of messages to send. Rainbow Dash, please return to Ponyville and warn everypony to take shelter. In thirty minutes, all of Equestria is going to get very hot, very fast."

"Got it!" Rainbow said, saluting as she took off. A faint sonic boom shook Canterlot in her wake.

Ponies across Equestria sheltered inside their homes and shops, or ducked under whatever convenient shade was available. Exactly thirty minutes after Rainbow Dash left Canterlot, the warm, inviting morning sun suddenly intensified into a shimmering, blazing fireball.

For ten minutes, Equestria baked under the sort of sun one would ascribe to an arid desert. Ponies panted, sweat lathering their coats. Curtains were drawn, heads were shaded with hats, and eyes were shaded with hooves.

When at last the merciless heat of the sun abated, the dense, cold fog that had enveloped Ponyville was no more. Pegasi cheered as they blew thin, reedy clouds over the town. A gentle spring shower fell like a curtain over Ponyville, rapidly cooling the baked ground and revitalizing the plants that had been harmed by the sudden heat.

Twilight Sparkle saw none of this, for she was sequestered in her basement laboratory, equipment humming, flasks and beakers bubbling, and various books, scrolls, and instruments flying around as she focused her full attention on five jars of fog sitting on her workbench.

The door opened, and Spike trotted down the stairs. "The fog's clear," he said. "It's still windy, though. Princess Celestia sent a note asking if you've found anything out yet."

Twilight shook her head. "Not yet. The only thing I know for certain is that there isn't a trace of pegasus magic anywhere in this fog. There's something familiar about it, but...I can't place it."

"I'll let her know you're still working on it," Spike said.

"Did the messenger ever get back from Cloudsdale?" Twilight asked absently.

"I'll go find Rainbow Dash and ask her," Spike replied. "I think she's resting up at Sugar Cube Corner. That round trip flight to Canterlot really took a lot out of her."

The reproach in his voice was unmistakeable, and Twilight grimaced. "I had to send her, Spike," she said. "It was the right decision under the circumstances."

"If you say so." Spike trudged up the steps. "I'll be back after I check on Rainbow."

A few minutes after Spike left, one of the jars of fog Twilight was studying abruptly turned a deep reddish-black color. She stared at it, eyes wide with worry. "That can't be good."

Spike arrived at Sugar Cube Corner at the same time as a grim-faced pegasus stallion, who ignored Pinkie Pie's greeting and marched right up to Rainbow Dash, who was slumped in a booth nursing an apple soda float. "News from Cloudsdale," he said gruffly.

Rainbow looked up. "What's the word?"

"The fog was also reported in Baltimare, Appleloosa, Hoofston, and Bentback Valley," the messenger said. "Nopony seems to know what to make of the wind. The foreman at the weather factory is sending messengers to Las Pegasus and Wingapore asking for help." He rustled his wings. "The only good news is that Princess Celestia's sunburst took care of the fog."

Rainbow sighed. "Tell the weather team..." She fumbled for a minute, then shrugged. "Tell them to go home and rest. Something tells me this isn't over yet, and we need everypony ready."

As the messenger left, Rainbow turned to Spike. "Twilight's still trying to figure out what's up with that fog," Spike said.

Rainbow nodded. "Thanks." She frowned. "You okay?"

"Yeah," Spike said. "I just...it bothers me that Twilight—"

"Didn't use you to send that message to Celestia?" Rainbow asked. At Spike's nod, she smiled. "Did she explain why?"

"Not really," Spike admitted.

"She needed a weather pony to deliver the message, in case the Princess had any questions," Rainbow said. "And sending it with me instead of having you send it gave her time to collect her samples and stuff before the Princess toasted the fog." She ruffled Spike's spines with a hoof. "Twilight knows what she's doing, Spike."

Spike waved her hoof off. "Yeah, I guess. It's just..." He paused. "I saw how wiped out you were when you got back. And you still look pretty beat."

Rainbow frowned. "Yeah...that's bothering me. I shouldn't be this tired just from a round trip to Canterlot..."

Rainbow fell out of the booth and landed on the floor, eyes closed. Spike gasped. "Rainbow Dash! Oh my gosh...PINKIE!"

Pinkie rushed over. "I know Dashie likes taking random naps, but she usually finds a cloud or a tree first..."

"I don't think she's napping," Spike said. "I think she fainted!"

Pinkie gasped. "Oh my gosh!" She jumped up onto the table. "SOMEPONY GO GET A DOCTOR! YOU AND YOU, HELP ME GET RAINBOW DASH UPSTAIRS! NOW!"

"I'll go tell Twilight," Spike said. "I'll be right back!" He cast one last look at the collapsed pegasus, shuddered, and ran as fast as his feet could carry him.

Twilight pushed against one of the samples with her magic. A dark pulse rippled through it, and the fog billowed blackly against the inside of the jar. A red spark snapped through the glass; she deftly absorbed it with a shield spell. "I know this magic," she muttered. "But it doesn't make any sense! It just isn't—"

"TWILIGHT!"

Twilight turned away from the jars of fog; the one that had turned black reverted to ordinary-looking fog. "What is it, Spike?"

"Rainbow Dash just fainted!"

Twilight gasped. "Rainbow fainted? Is it...what happened?"

"I don't know!" Spike cried. "I was talking to her at Sugar Cube Corner and then she just passed out! Pinkie's taking care of her now, and somepony's getting a doctor."

Twilight nodded. "Let's round up the others and head over there." She looked back at the fog samples. "After we see to Rainbow, I've got an errand to run."

"Nnnnnh..." Rainbow moaned as she stirred. Her head felt heavy and fuzzy. She opened her eyes and saw the ceiling of Pinkie Pie's bedroom. "Wha...?"

"You're awake!" Pinkie said, much more quietly than usual. "She's awake, everypony!" she shouted in a more normal tone.

"Keep it down, Pinkie, we're right here!" Twilight said.

Rainbow sat up and looked around. All her friends were crammed into Pinkie's room, watching her anxiously. A unicorn doctor was also present, studying her with a grave expression. "What's wrong?" she asked. "I didn't break a wing again, did I?"

"No, you're fine," the doctor said. "You just passed out from overexertion, is all."

Rainbow frowned. "I wore myself out? But how? That little trip to Canterlot and back was nothing!"

The doctor smiled. "Well...that might be the case under normal circumstances," he said, "but in your present condition, you really shouldn't be—"

"Rainbow, I am SO SORRY," Twilight cut in, leaning over Rainbow with tears in her eyes. "If I'd known, I would've made you send one of the others!"

"Known what? What condition?" Rainbow asked, blinking. She looked around at the room full of anxious faces and felt an icy shiver of dread race up her spine. "Oh horseapples. Am I dying? Is it wing rot? It's wing rot, isn't it? Please don't tell me I'll never fly again!"

The doctor chuckled. "Ah. So you didn't know." He shook his head. "You are not dying, Miss Dash. You are completely fit and healthy."

"Then what's wrong with me?" Rainbow demanded. "I know something's wrong with me! Tell me!"

Her friends all looked at one another, as if silently trying to decide who would break whatever terrible news awaited her. Finally, Rarity sighed and stepped forward. "Rainbow, darling...you're pregnant."

Rainbow's eyes shrank to pinpricks. "What the fuck?"

"More like who the fuck," Pinkie Pie said. "Who DID you fuck, anyway?"

"PINKIE!" Fluttershy yelled, cheeks red.

"Well it had to be somepony!" Pinkie said huffily. "I just wanna know who so I can throw him a you're-gonna-be-a-daddy party!"

Rarity cleared her throat. "Ahem. Putting aside the matter of Pinkie's complete lack of tact for the moment...forgive me, Rainbow, but...who is the father?"

Rainbow sighed, closing her eyes. "Soarin," she said. "We...a few weeks ago..."

"Wow, I didn't even know you two were dating!" Pinkie said.

"We're not. It was kind of an after-a-party, got-a-little-cozy thing," Rainbow said. "I mean, I knew I was in heat, but...it just happened, you know?" She sighed.

"There's no shame in that," the doctor said with a smile. "But for the sake of your foal, I suggest limiting your physical activity. You can still perform most of your normal duties. Just...no stunt flying, no racing..."

"No Rainboomin'," Applejack interjected.

Twilight sighed and placed a hoof on Rainbow's shoulder. "I'm really sorry I made you fly all the way to Canterlot," she said.

Rainbow waved her off. "I'd've done it even if I knew," she said, smiling. "It was important, after all. I couldn't just sit there and not do anything."

"Alright, everypony," the doctor said. "Our young mother here needs rest. She pushed herself way too hard today, and her body needs time to recover. We should really let her sleep for now." He packed up his black bag. "I'll visit you again tomorrow and go over what you need to know."

"Thanks, doc," Rainbow said. Her eyes began to flutter closed.

"Congratulations," Twilight whispered as she led everypony out of the room.

"Ah can't believe it," Applejack said. "Rainbow Dash, a momma!"

Rainbow's friends had retreated to the library. Pinkie had procured a supply of treats and drinks, and they were celebrating the 'good news'.

"Somepony needs to tell Soarin," Fluttershy said.

"I think Rainbow needs to do that herself," Twilight said.

"Today certainly is full of surprises, though!" Rarity said lightly. "First that ghastly fog, and now this!"

Twilight gasped. "The fog! I almost forgot!" The others were treated to a dizzying display of rapid-fire teleporting as Twilight disappeared and reappeared all over the library, each time wearing or carrying something new.

"Uhh, Twi? What're you worked up about?" Applejack asked.

"I need to go into the Everfree Forest," Twilight said as she examined a map.

"Didn't Rainbow Dash already say the fog didn't come from the Everfree?" Fluttershy asked, frowning.

"Yes, but..." Twilight hesitated, then sighed. "The fog samples I tested...I detected a familiar magical aura. If I'm right, something terrible has happened." She shook her head. "But the odds of anypony finding it..."

"Finding what?" Rarity asked.

"The Alicorn Amulet," Twilight said grimly. The others gasped.

"We're comin' with you," Applejack declared.

"No, you're not," Twilight said. "No offense, girls, but this is out of your league." She smiled. "I'll be fine. Don't worry!"

Before anypony could argue, Twilight had teleported out of the library.

Rainbow lay in Pinkie's bed, staring down at her belly. "I can't believe I'm pregnant," she rasped. "How the hay am I gonna be any kind of a mom?"

There was a gentle knock at the door. "Come in," Rainbow called.

Cup Cake peeked in. "Hello, dear. I just wanted to see if you needed anything."

"Actually, yeah," Rainbow said, motioning with a hoof for the older mare to enter. "What's it like? Being a mom?"

Cup laughed. "It's wonderful. But it's very tiring." She frowned. "I don't know how I'd handle the twins without Carrot and Pinkie." She tilted her head. "Are you planning on being a single mother? Or...?"

"I don't know yet," Rainbow said. "I'm still tryin' to get my head around this whole 'I'm pregnant' thing."

"Mmm, yes. It's a pretty major change," Cup admitted. "It took me a week to get used to the idea, and I'm married!" She smiled. "But you're one of the strongest, most determined ponies I know. I'm sure you'll be fine. Especially with Pinkie and all your other friends to help you!"

Rainbow smiled. "Heh. Yeah, I guess I won't be goin' through it alone. I mean, I'll be the only one goin' through it, but my friends'll be there to help..." She sighed. "Thanks."

"Don't mention it, dearie."

Magenta flames immolated a timber wolf. Three unconscious manticores lay tangled in brambles.

Twilight took a deep breath and consulted her map. "Almost there," she muttered. She flew past a patch of poison joke, wrapped in a health bubble to ward off its pollen. She soon found herself standing by a large, gnarled, ugly black tree root. The remains of the trunk were splintered, blackened, and jagged; the tree had been struck by lightning at some point. Embedded in the dirt at the base of this root were six rocks, unremarkable in every way but one—they had been carefully and deliberately arranged in a pattern that matched the stars on Twilight's flank.

Grimly, she set to work digging at the tree root. After fifteen minutes' work, she unearthed a small, locked chest. Carefully, hesitantly, she unlocked it and opened the lid.

She gasped at what lay inside.

The bottom of the chest had several thin holes in it, and there were broken, withered husks of thorny vines covering the dangerous artefact that lay within.

Hesitantly, she removed the Alicorn Amulet. Her eyes widened. What had once been a gleaming red-and-black pendant was now a corroded, colorless, twisted mess of pewter. The once bright red jewel set in the center had turned black; a jagged crack ran down the center.

She probed the amulet with her magic. It was completely inert. Absolutely no magical energies remained. She watched, distant and detached, as the dead husk of the Alicorn Amulet crumbled to dust and rained down on the lifeless corpses of vines in the chest.

"I see it is worse than I had feared," a cultured voice said from behind her. "It is not the Amulet itself, but its power that has disappeared."

Twilight spun around to face the zebra shaman, who shuffled her hooves restlessly. "You felt the touch of the Alicorn Amulet on that fog too?"

Zecora nodded. "Like you, I assumed the Amulet was taken. Now, it seems we were both mistaken."

Twilight frowned. "Whatever's happening right now...it's connected, somehow, to the Everfree Forest going out of control before we returned the Elements of Harmony."

"I must agree, but how? It is difficult to see."

Twilight nodded. "The wind and the fog didn't come from the Everfree Forest. Which means whatever absorbed the Amulet's power has to be somewhere else. But where?" She sighed. "I need to run some more tests, do some more research. Let me know if you find anything, okay?"

Zecora nodded. "Guard yourself well, Princess Twilight. I sense terrible things will happen tonight."

When Twilight returned to the library and shared her findings with the others, they were noticeably worried, but they seemed confident in her ability to uncover the truth and find a way to stop whatever was happening. Bolstered by her friends' reassurances, Twilight remained sequestered in her lab for the rest of the day, taking a light supper while continuing her research. The others took turns looking in on Rainbow Dash, who was already up and about, but had been sternly forbidden from flying home.

Celestia had been perturbed by Twilight's findings, and cancelled all of her afternoon appointments to research the Alicorn Amulet.

By evening, Rainbow Dash had migrated from Sugar Cube Corner to Fluttershy's cottage, where an impromptu party lasted well into the evening. Spike had dropped by to tell them that Twilight was still researching the strange wind and fog.

Night fell, bringing with it a sharp, biting cold. The fog slowly began to roll back into Ponyville. As three mares made their way home from Fluttershy's cottage, strange sounds whispered on the bitter wind, prickling their skin with gooseflesh and quickening their pace.

Princess Luna stood in the Royal Gardens, surrounded by Canterlot nobility and bored out of her skull.

It was some minor noble's birthday, and he had requested a garden party under the full moon. While Luna was delighted that one of her subjects appreciated her beautiful moon, she would much rather be strolling through the nightmares of young fillies and colts, or investigating one of the intriguing nightclubs she had heard so much about. Instead, she was stuck making idle conversation with dull, uninteresting ponies.

Fancy Pants, one of the few high society ponies Luna got along with, trotted over to her, casting a pensive gaze skyward. "I say, Your Highness...doesn't something seem a touch...off about the Moon?"

Luna followed his gaze and blinked. A faint shadow was crossing the edge of the Moon. She frowned. "There are no clouds in the sky. What is that?" Spreading her wings, she nodded to Fancy Pants. "If you would, please make my apologies to the other guests. This requires my immediate attention."

"Of course, Princess."

As Luna rose into the sky, she probed the Moon with her magic. Its resonance felt off; the tides were behaving incorrectly, and the Moon itself felt...dulled.

She studied the Moon for some time. As the minutes passed, the shadowed area took on a forbidding crimson tint. When fully a third of the Moon was obscured by the red shadow, a pattern of darker blotches spread across the face of the Moon. Luna gasped; while she had never personally witnessed the pattern of darkness marring the Moon's surface, she had seen it in murals and histories of her thousand-year absence.

The pattern was more than halfway formed now. Luna, heart hammering in her chest, teleported directly to her sister's suite.

Twilight had finally succumbed to exhaustion at midnight. Just as she was climbing the steps to her bedroom, somepony began pounding furiously on her door. With an irritated groan, she shuffled to the door and threw it open.

"Twilight!" Applejack cried. "You gotta see this!" Without waiting for a response, Applejack dragged Twilight outside. "Look up at th' Moon!"

Blearily, Twilight directed her gaze skyward. What she saw froze the blood in her veins. Suddenly completely awake and alert, she looked around.

Dozens of ponies had emerged from their homes. A dozen more were running around banging on doors. A crowd of ponies was converging on the library.

Twilight gulped. "Go get Rainbow Dash and Fluttershy, then bring them to the Town Hall," she said. "I'll start herding ponies in that direction."

"Twilight...what's it mean?"

"I don't know," Twilight said. "But...it's bad."

Overhead, the moon glowed red as blood.

"Sister!" Luna cried as she appeared in Celestia's bedchamber. "Wake, Sister! Something is terribly amiss!"

Celestia stirred, slowly removing the golden sleep mask from her eyes. Her mane fell in pastel tangles across her face as she lifted her head to stare at her sister. "Luna? What..." A yawn cracked her muzzle wide. "What time is it?"

"Nevermind the time, Sister! You must come at once!" Luna stormed over to the balcony and threw the great doors wide.

Sleepily, Celestia lowered herself out of her bed, bare hooves making little noise as she padded over to her sister. "What is it, Lu—?" Her eyes widened as she stared out into the night sky. "But...that's impossible!"

The shadow of the Mare in the Moon was nearly full now, and burned a deep, angry red against the face of the Moon. A bloody tint spread across the Moon with the shadow, staining the silvery orb a rusty orange.

Luna looked at her sister with wide, frightened eyes. "Celestia...what's happening?"

"I...I don't know, Luna," Celestia whispered. "I've...never seen anything like this before."

As more of the Moon's surface was consumed with the bloody tint, Celestia's jaw hardened. "We must go to Ponyville," she insisted. Without waiting for her sister's reply, she launched herself from the balcony, wings spread wide. As soon as she cleared the tower, she disappeared in a blinding golden flash. Luna followed suit, melting into a pool of shadows and vanishing.

Twilight, Spike, and all their friends stood outside the town hall, along with a crowd of confused, nervous ponies, all staring up at the red Moon. "What's going on, Princess Twilight?" a terrified foal whispered.

"I don't know, my little pony," Twilight said. "I just..."

Celestia and Luna appeared in front of Twilight, startling the already nervous crowd. Several ponies whinnied in alarm and scattered for the fringes of the crowd.

"Remain calm, my little ponies!" Celestia shouted. She stamped her hoof; it failed to make the satisfyingly loud noise it normally would, for her hooves were still bare.

Several ponies quickly took note of the fact that while Luna wore her full regalia, Celestia was, for lack of a better word, nude, with her mane in complete disarray. Celestia took note of the wide-eyed stares she was receiving, and blinked. "Is something wrong?"

Applejack coughed. "Uhh, not at all, Your Highness. It's just...well..."

"You're kiiiiinda naked," Pinkie Pie chimed in.

A hairbrush appeared from...somewhere, limned in Rarity's gentle magic. "Allow me, Your Highness," she said as she attacked Celestia's limp, stringy mane.

Despite the gravity of the situation, Luna found herself letting out a soft chuckle. Celestia blinked several times. "Oh. Right." She coughed daintily. "I was, after all, asleep not five minutes ago."

"Luna, Celestia...what's going on?" Twilight asked.

Luna sobered and looked to the sky. "I do not know, Twilight Sparkle," she said. "This unnatural Moon is not of my making. And..." She looked down. "I cannot remove this taint from the Moon. It is as if my power is being blocked..."

"Does this have anything to do with the fog?" Rainbow Dash asked, trotting up to the princesses.

"Rainbow! You should be resting!" Fluttershy admonished.

Rainbow waved Fluttershy away with a wing. "I'm fine!" she insisted. "It's not like I'm gonna drop the foal right now! I mean, I just got pregnant!"

Celestia gasped. "You're with child?"

"Aheh...yeah. Totally not awesome, huh?" Rainbow laughed. "But anyway, the fog?"

"It's possible," Celestia hedged. "Twilight? Do you have anything new?"

"I'm still studying the samples," Twilight said. "They're giving off what's unmistakeably the magic of the Alicorn Amulet, but so far I haven't been able to figure anything else out."

"Look!" Spike cried, pointing up. Everypony followed his gaze. The Moon was now fully red, and the shadow of the Mare in the Moon, fully formed, stood out vividly.

Luna suddenly tensed up, thrashing her head. She reared, kicking her legs in the air and whinnying.

"Sister?" Celestia asked. "Are you alright?"

"Help me, Celestia!" Luna cried in a strangled voice. Her eyes began to glow. "Something is..."

Luna threw back her head and screamed. Blood red light shone from her eyes.

"LUNA!" Celestia shouted.

Luna rose into the air, wings beating mechanically. The light pouring from her eyes began to engulf her, becoming a vivid, angry red shell.

Twilight gasped, taking a step back. "Celestia...this looks almost like the night...!"

"Yes...it does..." Celestia stared at the pulsing, strobing sphere of blood red magic, eyes wide in fear.

A beastly scream of rage split the night. Many ponies in the crowd screamed and ran, nearly trampling each other in their rush to escape whatever was happening. Twilight hastily cast a protective shield around her friends.

The angry sphere melted into the ground, dripping like blood. As the last of the menacing magical aura faded away, the remaining ponies gasped, and an aura of dread settled over them like a chilly blanket.

Luna's legs and horn elongated. Her coat darkened from deep midnight blue to black. Her great, feathery wings rapidly moulted, growing larger and leathery, becoming menacing black bat wings. Her shimmery mane and tail changed from their usual blue to a dark, angry red. The Regalia of the Night metamorphosed into the war raiments of Nightmare Moon, though instead of the cold blue they had been before, they were now glistening crimson in color. She grew fangs; her eyes became black slit pupils in solid red orbs. Lastly, her Cutie Mark changed into the very image of the menacing blood red full Moon that hung overhead.

She hovered high above the square, beating her leathery black wings slowly. Celestia stared up at her in horror. "No..." she whispered.

Twilight lifted into the air, anguish in her eyes as she stared at the transformed alicorn. "Why, Luna?" she cried.

Cold red eyes regarded Twilight. YOU ARE THE PRINCESS OF HARMONY.

"What...what's going on?" Fluttershy squeaked, hiding behind Pinkie Pie.

"We can't fight Nightmare Moon again," Applejack said softly. "Not without the Elements..."

"That...that isn't Nightmare Moon," Celestia said thickly.

The creature that was once Princess Luna regarded them all with contempt.

The creature flew, impossibly fast, straight at the Moon. When she was but a speck against the ominous red Moon, she vanished...

...as did the Moon itself, leaving the night dark and still.

Celestia continued to stare up into the sky in shock. Twilight glided down to her side and leaned up against her, covering her with a wing.

"Luna..." Celestia whispered, bowing her head. Tears spilled from her eyes.