Celestia paced back and forth across the cold stone beneath her hooves, her face contorted with concern. In the void of still air surrounding her, she glanced at the mirror; its polished surface gleamed with a flawless shine, and the purple frame that housed it glittered as light caught the amethysts embedded within. Her throat dry, she gulped before resuming her pacing, staring at the floor.

“Sister, we know thou art concerned for thy student, but we can plainly see it is not the sole cause of thy distress,” Luna said, her sapphire eyes following every step.

“Yeah, Auntie,” Cadance said, taking a small step forward. “I’m worried about Twilight as well, but you look like you’re about to start crying.”

Celestia stopped, her eyes wide. Slowly, she turned to face her sister and niece, but found herself peeking to them from behind her flowing mane. It was a small miracle that all of Twilight’s friends had departed to sleep briefly, otherwise she was sure she wouldn’t be able to explain her concerns. As calculating and collected as she normally was, she felt small and exposed, like a filly caught doing something wrong.

“I… I can’t say for sure,” she squeaked. “But I fear for Twilight’s safety.”

Luna’s gaze hardened as Cadance put a hoof over her mouth.

“Pray tell why thou hast sent her on this journey then,” Luna demanded. “If thou knew of the danger, why wouldst thou allow thy most prized pupil to undertake such peril?”

“Because, Luna,” Celestia said. “Sunset Shimmer is a crafty, intelligent pony, and Twilight needed to gather the Element of Magic herself since I can no longer even hold it!”

Luna flinched at the sudden shift in Celestia’s tone, but she maintained eye contact. Realizing her folly, Celestia turned away and frowned.

“What doth thou imply?” she growled.

“Nothing, sister,” Celestia whispered. “Forgive me—I meant nothing by it.”

“Then tell us what’s wrong, Auntie!” Cadance cried. “We all care about Twilight as much as you do!”

Celestia closed her eyes, forcing herself to remain standing in place. The sheer concern in Cadance’s voice was enough to make the weight on her chest almost unbearable.

“Sunset…” she began. “Sunset is bent on her desires. She is crafty, yes, but she has resorted to violence in the past. I fear that she and Twilight are fighting right now, and the battle is going poorly for Twilight.”

A stern silence filled the room as Celestia breathed deeply. Despite what most ponies had said, voicing her concerns didn’t alleviate them. In fact, she felt the weight double and squeezed her eyes shut.

“Dost ye not have faith thy pupil can defeat the former?” Luna asked.

Celestia lowered her head, straining to hold back the wave of emotions running through her. Fear, anger, concern and bitterness all mixed inside, creating the weight that pressed down on her mind and body.

“I believe she can, Luna, but…” She sighed. “I don’t believe Sunset will allow Twilight to simply walk away from this easily.”

At that moment, a white light poured from the mirror, causing all three mares to yelp.

“The portal’s opening!” Cadance shouted. “I’ll get the others!”

As Cadance galloped out the doorway, Celestia trotted over to Luna, both of them staring at the mirror. The uneasy concoction of emotions in Celestia’s chest began to evaporate, leaving her with a sense of elation and dread.

“Luna, promise me something,” Celestia said, her throat tight. “If Sunset steps through the mirror and I cannot act, force her back through for me.”

“Surely,” Luna said before spreading a wing over her sister’s back. “We shall, but answer us this before we do so: why?”

“Because,” Celestia breathed, “it means Twilight will not be coming back.”

As Luna turned to face her sister, the light shined brighter. Both of them flinched and backed away, covering their eyes as a high-pitched hiss filled the silence.

Celestia opened one eye to see the flawless surface of the mirror ripple. The mirror flashed one last time before the light faded, causing both sisters to rub their eyes to rid the spots. The hissing faded away... replaced by the sounds of a pony sobbing.

Celestia snapped her eyes open and her ears stuck straight up; she knew that voice anywhere.

“Twilight!” she cried, turning to the mirror as a large grin broke upon her face.

Sitting at the foot of the mirror, the familiar form of Twilight Sparkle sat hunched over, Spike gently rubbing her back with a morose frown on his face. Her mane covered her face, and her wings drooped around her like a wet blanket. Celestia’s smile immediately fell as she saw her, the dread returning to her chest.

“What is it?”

She took a step forward. Her gold slipper clinked against the stone pedestal and Twilight recoiled, throwing her wings up to protect herself.

“Twilight, it’s me. It’s Celestia,” the princess cooed, taking another cautious step.

A few more sobs escaped Twilight as Celestia stopped, her blood turning to ice. Twilight didn’t seem hurt in any physical way, but Celestia had rarely seen her old student cry. For Twilight to ever break down like she had now heralded something that truly upset her. The dread continuing to build, Celestia chanced one more step forward.

“Twilight?” she asked. “Are you all right? Did you recover the Element of Magic?”

“I… I couldn’t…” Twilight whispered back, her voice as shaky as her body. “I… I didn’t m-mean to…”

The dread became terror in Celestia’s chest as she felt her heart skip a beat. “You didn’t mean to do what?”

Twilight lowered her wings and looked up at Celestia. Her bottom lip quivered, and her eyes were puffy and red from crying. Glistening trails ran down her cheeks as she struggled to speak, her words coming out as squeaks and moans.

“What happened, Twilight?” Celestia asked, looking her straight in the eyes.

“I-I-I…” Twilight began before burying her face into her hooves.

Celestia’s eyes widened as Spike forced his shut.

“I killed her!”

Celestia’s eyes widened as Twilight began sobbing again. Her hooves quivered inside her slippers. “Y-you what?”

“I was j-just trying to get m-my Element back!” Twilight stammered. “I-I didn’t w-want to hurt her! Sunset fought back a-and the m-m-magic just… augh!”

Renewed crying filled the emptiness as her words echoed in Celestia’s ears. A cold emptiness filled the void as the pieces fell into place. She heard Luna gasp behind her, and she took a step back.

“No…” she whispered. “No. Magic can’t… it can’t…”

Her stomach tightened and twisted violently as the final piece clicked into place. Immediately, tears filled her eyes as she brought her hooves up to her mouth, trying to stop the urge to puke. She squeezed her eyes shut to dam the tears, but they flowed regardless.

“I-I’m so sorry, Princess,” Twilight whimpered. “I swear I d-didn’t want to hurt—”

“N-No, Twilight,” Celestia said with a pained smile. “I-It’s all right.”

Celestia opened her wing to Twilight, who immediately ran to her, tears streaming down her face like a little filly. She threw her hooves around Celestia as she closed her wings, trying to fight back her own tears.

“It’s all right,” she whispered to Twilight, her own eyes misting. She leaned forward and clutched Twilight tight to her chest. “It’s all right. Everything is all right."

“Everything will be all right…”

Celestia woke with a start as she thrashed about in her silk sheets. Beads of sweat trickled down her forehead, causing her to slow down and take a few deep breaths. Closing her eyes, a shiver ran through her body as she recalled the dream with vivid clarity.

Or rather, the memory.

The replay ran through her mind, bringing up the uncomfortable puking sensation in her stomach again. She rolled over, hoping to alleviate her twisting gut, and stared out at the full moon hanging in the sky. While Sunset had left her and used the knowledge she had learned to manipulate things in the other world, she was still Celestia’s student—same as Twilight. Before all the anger and self-centeredness, Sunset was a kind and sweet little unicorn who had the same wide grin as Twilight when she learned something new.

From the other side of the room, Celestia heard a small bump. Her ear instantly turned to it as she leaned over on her back, raising an eyebrow at the darkness. Her sharp ruler’s instincts told her she was alone in the room, but she cast a quick spell to confirm it anyway. Satisfied, she placed her head back onto her satin pillow and snuggled in before another bump rang out, this one louder than the last.

Craning her neck around once more, she knit her brow as hushed commands came through her door. She cast another spell—this time to amplify the noises—and listened in as she cast her sheets off.

“—if it finds Her Highness, who knows what will happen?”

“But, sir, that aura isn’t natural! Not even our best spellcasters can clarify what is making that thing appear!”

“It is our duty to protect Her Highness while she sleeps! Even if we don’t know what we’re facing, protecting her is our top priority. Do I make myself clear, soldier?”

“Sir, yes, sir!”

“Good, and keep your voices down. We don’t want to wake her if we can—”

Celestia had just put her slippers on when a much louder bump rang out in her room, causing her to look around and the guards to grow silent for a few moments.

“It came from the Archives, didn’t it?” one of the guards asked.

“Right where the aura is appearing,” a third added.

“Be ready for anything. If somepony even so much as approaches this door without proper authorization, blast them on—”

Celestia lit her horn and the doors swung open in a magnificent arc, revealing the few guards standing at attention around it. They all looked behind and then up to her, their faces pale.

“That will be quite unnecessary, Commander,” Celestia said calmly as she stepped out of the room. “I would like you to escort me to the Archives immediately so I can ascertain what is making this dreadful disturbance.”

They all turned to each other, confused and terrified expressions on their faces. “Y-Yes, Your Highness,” the one in front said before bowing his head.

Together, they proceeded down the hallway. The guards fanned out around her, forming a perfect diamond as they pressed on. Celestia marched forward, pondering who or what could be causing the disturbance in the Archives. Sure, there was a vast amount of ancient tomes and artifacts that still eluded the comprehension of some of Equestria’s best scholars, but so far all the violent ones were locked away deep in the Royal Vaults of Mysterious Objects, which made Celestia grimace. It was a rather poorly named hiding spot for them, especially since some of them could explode or cause inexplicable conditions to occur in unsuspecting passer-bys.

There were a number of things that caused strange auras and sightings to appear without any real explanation. There was a shard of the Crystal Empire that Celestia housed in the normal Royal Vault that could make a diorama of the Empire appear, as well as the Stone of Infinity that could warp space around it with an eerie purple aura. Then there was the original tome of Clover the Clever that self-illuminated and scared the wits out of anypony near it, as well as Star Swirl’s book on the study of the sun, which would occasionally form a miniature version of Celestia’s charge in midair.

Despite the series of thoughts and possible culprits whirling about in her mind, Celestia did not fail to notice the vast number of guards and staff dashing about through the halls. Each one had a look of concern on their face, which only worsened each time more thuds echoed through the stone halls.

Eventually, the troupe stopped at the doorway to the Archives, a set of regal brown hardwood doors inlaid with gilded carvings of books and scenes of magic. Around it stood a line of Royal Guardsponies, each flinching nervously as the bangs grew more frequent.

“Stand aside, my little ponies,” Celestia commanded as she walked to the door, head held high.

Immediately, they all nodded and parted as she strode up to the door, examining it with a suspicious look. “Commander, when did this aura you speak of appear?”

“Just after eleven o’clock, Your Highness,” the leader said in a stoic yet shaky tone. “Right after Princess Luna left to make her nightly rounds.”

Celestia eyed the door even closer, trying to decipher it. The gilded seals upon the door did much more than add a tasteful amount of decor to a drab hallway, especially after the first few artifacts began to act up. She studied each glyph, looking for the telltale signs of where the danger was. Each one of the scenes of magic glittered back normally, from teleportation to transformation.

“Odd,” she murmured.

“My Princess?” the closest guard asked.

“Which wing is the aura manifesting in?” she asked as another loud boom echoed from the Archive.

“I, uh, I believe it’s in the Star Swirl the Bearded wing,” the commander said.

Scanning over the glyphs on the door, Celestia passed through the section devoted to Star Swirl, noting the sections looked normal as she did so. The tomes of his adventures, the concept spell shelves, even—

She paused as her eye caught an abnormal glint in the gilded seal representing the section devoted to his incomplete or darker works. While hardly any of those recordings and scribblings acted up, they were known for being full of powerful magic. Most were for beneficial purposes—like the incomplete friendship spell that Twilight had solved—but a select few contained spells had been deemed too dangerous for use outside of controlled conditions.

Narrowing her eyes, she remembered her dream of Sunset’s demise and frowned. Shortly after discovering the mirror, her student had embarked on a binge of this section to find more information on it. Thankfully, all knowledge regarding the mirror was passed down verbally, so there would be no chance of anypony learning what it was truly capable of. Still, Sunset had been perusing this wing before disappearing through the mirror, and her dream earlier made this seem too close to be coincidence.

Celestia let out a sigh before turning to the guards, each staring at her with a concerned look.

“My loyal guards,” she said in an even voice, “I do admire your dedication, but I will need to see this for myself, alone. If I do not return in less than one hour, send for my sister and my pupil.”

“But, Your Highness!” the commander shouted. “Whatever is causing this ruckus is dangerous and—”

“And should be dealt with by the pony with the most knowledge about these strange phenomena,” Celestia finished. “Namely, Star Swirl’s own pupil and the owner of such dangerous artifacts.”

The commander opened and closed his mouth repeatedly, looking like a fish trying to breathe. A small chuckle came to Celestia and she strode by him with a comforting smile.

“Of what use am I if I do not confront the dangers of my kingdom and subjects directly, commander?” she asked. “I know the Archives well and can, at minimum, contain whatever is in there.”

At her words, the commander straightened up with a pained look. “Allow Her Highness in and barricade the doors afterward,” he ordered the others. “If she has not returned in one hour, we will send for Princess Luna and enter the Archives ourselves!”

Wordlessly, each guard nodded and stepped aside, allowing Celestia full access to the doors. Her horn lit and they creaked open as another boom came from within, this one the loudest yet. Steeling her nerves, Celestia strode in and made her way to the Starswirl section as the doors shut with a solid thud.

Gulping hard, she strode between the towering shelves of ancient books and scrolls, her eyes locked on an invisible spot in front of her nose. She made her way through several rows when another boom rang out, shaking the dust from the shelves. She blinked as she realized how close it sounded, and shook herself from her stupor. Turning to the right, she peered down a smaller aisle and swallowed; the aura lit up the whole rear section of the Archives, dispelling shadows as far up as the ceiling.

Steeling her nerves, she marched toward the light, hearing two more booms echo throughout the room. She quickened her pace as her inner fears got the better of her imagination, filling it with images of monsters trying to break their way out of the castle. Her graceful gait became a trot of concern.

She closed the gap quickly and paused behind a bookshelf as she caught her breath. Shivering slightly, she put on her best confident face and rounded the corner, ready for anything. What she saw, however, caused her to freeze in terror.

Glowing like the sun itself stood a familiar pony with yellow and red locks in her mane and tail, both swaying in the ethereal wind like Celestia’s own. Her back was turned, but Celestia briefly felt her heart stop.

“Sunset?”

Immediately, the radiant form of Sunset Shimmer cast a glance back at her, her once stunning blue eyes replaced by a harsh white light. A sneer crept along her muzzle as she turned to face Celestia.

“My dearest teacher,” she said a distorted voice. “How nice of you to come back.”

“S-Sunset,” Celestia replied, her eyes wide. “H-How?”

“How am I here when I was killed by that stupid new student of yours?”

Sunset’s sneer grew larger as she took a step to spin around. “That mirror wasn’t the only secret Star Swirl detailed in his tomes,” she hissed with a playful edge.

“B-But… but…” Celestia said, fumbling for the words.

“Ha!” Sunset shouted before throwing her nose into the air. “And here you told me you were Star Swirl’s pupil. Didn’t pay too much attention to his works and spells, did you?”

Celestia’s shock evaporated; her gaze hardened into a glare.

“Star Swirl was a brilliant pony—the most gifted spellcaster to have ever lived,” she replied. “Yet even he knew what was worth teaching to his students and what should be kept hidden.”

“Oh, do you mean like how a mirror exists that could grant me the powers of an alicorn princess?”

Sunset sneered. “That was just the tip of the spells and knowledge he wrote. He gave you his life’s work and you repaid him by keeping his knowledge under lock and key.”

Celestia felt a twinge in her chest.

“He taught me knowledge is a gift and how to use it to better others, not to cheat one’s way to power and to evade death.”

Celestia broke eye contact as Sunset threw her head back and cackled. Glancing about the floor, she spied a ring of books lying behind Sunset and what looked like an old Gala mask.

“Then why did he write it down?” Sunset shouted back. “Why place such—as you put it—dangerous knowledge in writing if it was not meant to benefit those who could use it? Explain that!”

Celestia forced herself to stand taller. Her caring leader eyes were gone; only fury burned in those pink irises.

“I need not explain myself to you, Sunset,” she declared, her voice bouncing off the shelves and walls around them. “I did what I had to do for the safety of my ponies, not for your gain.”

“My gain? Star Swirl already assured my gain with his wonderful writings!” Sunset shrieked. “Not only the secrets of the mirror, but the way to implant memories into objects and live forever!”

Celestia’s piercing gaze broke at that, her eyes widening into shock again as she gasped.

“What? Where did you find that spell?”

“Your chambers are not nearly as well guarded as you think they are!” Sunset replied, her grin turning from a sneer into one of triumph.

Celestia’s blood ran cold. While most of Star Swirl’s writings were housed here in the Archives, she had remembered his final instructions to her regarding his works: the request to keep his darkest magical writings away from everypony at all costs.

“His greatest works of magic, all housed in a single tome and rotting away in your private bookshelf! How dare you claim to be protecting your subjects and honoring his legacy by locking away spells that can change our world!” Sunset bellowed.

She pointed a hoof at Celestia. “I will honor his legacy like no other pony can! I have used the mirror in ways he only tested, and I have performed the spell to cheat death itself! I will be reborn into a new body and cease to be a mere memory, and nothing you can do will stop it!”

Celestia’s stomach fell as the words rang throughout the room. Squeezing her eyes shut, she grimaced as Sunset began to cackle again. She hadn’t changed at all; all the time she had spent in the mirror world—not even Twilight’s obliteration of her— had failed to alter her arrogance.

“No…” Celestia whispered. “No…”

Tears began to burn her eyes as she looked back up at Sunset, watching the sneer morph into a maniacal grin. “You are not worthy of his teachings, Sunset!”

The glowing form froze as the words cut the air.

“You were never worthy!” Celestia continued as tears began to stream down her cheeks. “All your arrogance, all your selfish tendencies—everything you have shown me proves Star Swirl was right in asking me to hide his works! You are exactly the kind of pony he feared would abuse his spells, and look at where it got you!”

Sunset’s grin hardened into a snarl, but Celestia pressed on.

“You died, Sunset! Your arrogance led to your death, just like it did to Sombra! Star Swirl crafted that spell to help those who died wrongfully!”

“I did die wrongfully!” Sunset bellowed. “You sent your wretched new student to kill me!”

A bright light burst from Sunset, releasing the familiar boom as Celestia turned away to shield her eyes. Glancing back, she noticed Sunset was glowing less and her irises had returned.

“I don’t care if you think I’m not worthy of his spells,” Sunset growled. “I will recover my body and then show the world what a real princess can do!”

Sunset stomped her hoof into the stone floor and Celestia decided to act. Focusing her energy, she felt a small tugging sensation as she teleported behind Sunset and immediately made for the book at the center. Sunset yelled as she dove for it as well, but Celestia’s forelegs were longer. Kicking the book away, she braced herself for Sunset’s hooves to hit her, but blinked when nothing happened. She looking around.

Sunset was frozen in place, her face contorted into one of anger and shock. Without warning, an earsplitting scream came from her as her body began to glow again, this time with a harsher glare.

“What have you done to me?”

As Sunset’s body began convulsing, Celestia glanced over to the book, casting blue sparks from its pages. She bolted over to it without hesitation and stood over it, her eyes wide with terror. Several more booms rang out from behind her.

Grasping the book with her aura, Celestia turned back to Sunset and watched as she forced herself to stand upright, also pressing a hoof to her forehead. With a frown, Celestia looked back at the book and lifted one of the pages.

“Sunset, I cannot allow you to desecrate the work Star Swirl spent his life on,” she said in a shaking voice as her eyes focused on the pages.

“Don’t!” Sunset screamed.

“Goodbye,” Celestia whispered as she closed her eyes.

A tearing sound filled the room shortly before Sunset let loose the loudest scream Celestia had ever heard. Tears cascaded down Celestia’s cheeks as she ripped more and more pages from the book, keeping her eyes shut, unwilling to watch Sunset’s second demise. More booms rang out as Sunset continued to scream, her pitch ever increasing.

With the last page finally torn from the book, one last blast pressed on Celestia with a pulsing shockwave. She remained rooted in place, her eyelids still crushing together. Bookcases creaked and fell over, spilling all of Star Swirl’s legacy onto the floor with a series of mighty crashes. Seconds passed in a thundering ruckus, and she kept her eyes closed, a wing up to shield her face.

As the crashing finally ended, Celestia lowered her wing and peeked through her thinly parted pinions. The air shone, thick with freshly disturbed particles of dust.

“Mommy!”

Celestia’s eyes flew open in shock as she spun to where Sunset had been standing. There was a perfectly rounded indent in the floor where she had been, but sitting in the middle was not the mare Celestia expected to see. Instead, a small filly with a radiant gold mane and coat sat there, crying as she gingerly rubbed her eyes.

“Mommy! Where are you?” she wailed.

Celestia blinked once as her mouth dropped open. She took a shaky step toward the filly, her mind racing with confusion. Her golden slipper clacked on the stone below and the filly peeked up through her hooves.

“M-Mommy?” she asked.

“Uh, I-I…”

The filly frowned as she unsteadily rose to her hooves. She looked at Celestia again. “Help me, Mommy.”

Before Celestia could respond, the thunder of hooves echoed in the Archives. The filly’s eyes filled with terror as she tried to take a step to Celestia, but her leg gave in and she fell to the floor, looking up at her with watery eyes.

“Mommy, I can’t walk right!” she cried.

Celestia’s heart panged, but before she could act, two Guardsponies placed themselves between her and the filly.

“Stay back, Your Highness!” one of them roared as he glared at the filly. “We’ll escort you to safety!”

The guards began to back up, forcing Celestia to take an uneasy step backward. The filly sobbed again.

“Don’t leave me, Mommy! Don’t leave me!”

The filly’s pleas shook something loose in Celestia’s mind. She turned back to the filly and shoved her way past her guards. In a few graceful strides, she stood tall as the filly trembled before her. Her horn alight, she sat down next to the filly, who leapt into Celestia’s chest and buried her face into it. Young tears darkened her white coat.

“P-Princess?” one of the guards asked.

Celestia, however, was enraptured by the tiny golden body huddling against her chest. She looked like Sunset, but did not have the same red streaks in her mane and tail. When the filly finally glanced up at her, she saw the purest sky blue eyes staring back at her. In shock, Celestia nearly dropped the filly, who shrieked and hugged closer to Celestia.

“Mommy, that’s scary,” she whined as she shivered against her.

“Your Highness?” the guard asked again.

Craning her neck to see them, she saw them stare at the filly in her hooves. She glanced down at her before looking back at them.

“You two,” she said. “You are hereby sworn to absolute secrecy of this. Not a single word of what you just saw to anypony—not your superiors, not Princess Luna. You will report directly to me now. Is that clear?”

The Guardponies blinked and looked at each other; the filly huddled tighter against her.

“Is that clear?”

Immediately, they both saluted crisply. “Yes, Your Highness!”

“Good.”

Celestia’s aura enveloped both her and the filly. “Meet me in my chambers in one hour. We will discuss your new assignments there.”

Princess and filly disappeared in a flash of golden light.