Something was off as she entered the building, not that she was entirely sure what it was. She could just feel an odd taint creeping through the building. To her magically honed senses it felt like a strange mist that was slowly oozing between their hooves and spreading out into the streets of Ponyville through the open double doors. She did not know what it was, or why it made her feel so uneasy but as she moved towards the front of the crowd she had a horrible feeling that the alicorn on the balcony was not going to be her tutor, Celestia, but her tainted sister.
The mayor stepped forward to give a speech but Twilight was not listening. She was too busy paying attention to the fact the darkness was building around the balcony where the Princess was due to appear. Something or somepony was coming and the darkness knew it. Twilight just did not know how she was supposed to deal with that fact.
If she was the ‘Guardian of the Shadows’ now, then this was her first test in her new role. She would have to stop Nightmare Moon here, before she could do any damage. She just was not sure how.
“And now,” The mayor announced after thanking everypony for their hard work, “I welcome to Ponyville, Princess Celestia!”
Fluttershy’s bird chorus started up and Twilight held her breath, praying that she was wrong. That the tales of darkness and shadows in Celestia’s letter had made her just image the mist at her hooves and the creeping tendrils of power she could feel surrounding the balcony and reaching behind the curtains.
When they opened, Princess Celestia was missing, causing panic to start rising in the assemblage, including Twilight, who sidestepped, having feared this would happen. Fluttershy’s birds trailed off mid-chorus as Rarity let out a frightened cry of, “She’s gone!”
A dark and slightly deranged cackle started as a purple and black fog swirled around in a tornado of power. Power that was far too reminiscent of the pulse of magic that had erupted from the puzzle when she had completed it for Twilight’s liking, but like it had been multiplied by a thousand.
“Oh horsefeathers…” Twilight whispered to herself as she watched it explode out, coating the walls and ceiling in the same weird maelstrom of an odd mixture of purples, blacks and blues. With the tornado gone, a midnight blue alicorn whose mane and tail were made up from the night sky and flowed like water stood tall and proud where Princess Celestia should have stood. Her silver armour glinted ominously in the strange light that was cast by the power and she looked around with a toothy smirk at the terrified crowd below.
“Bow before your Princess.” Nightmare Moon demanded, “For I have returned and the night will last forever!”
Twilight could feel the power coating the room like a lead weight baring down on her and the temperature had dropped several degrees, leaving most of those in the room with her shivering, though it was hard to tell if it was because of the cold or the fear. It was hard to think through the oppressive atmosphere and Twilight struggled to react to the possessed alicorn’s ravings.
“Where’s the Princess!? The real one!” Rainbow Dash demanded, trying to fly up to the balcony only for Applejack to catch her tail between her teeth and hold her back.
“What’s the matter?” Nightmare Moon demanded with a snarl, glaring at the Pegasus pony, “Am I not royal enough for you? Does the crown of the Night Goddess no longer matter after a thousand years? What of the crown I wore five thousand years ago?! Do you know who I am?!”
“I do!” Twilight bellowed, saving Pinkie Pie from attracting the attention of the dark creature on the balcony by bellowing over her, “I know who you are! You’re Nightmare Moon!”
Several ponies whinnied in terror as the alicorn turned an amused smirk on her, only to freeze, her eyes widening as she took in the unicorn who had called out. “You.” She hissed, anger clear on her face, “You will not stop me this time. I will kill you again! And this time you won’t come back!”
Twilight did not understand what she meant, but she did understand what the wave of purple the alicorn sent at her meant and she threw up a hasty shield spell that protected not only herself but anypony close enough to her to be hit. The powerful attack washed down the sides of her shield and joined the darkness coating the floor around her.
“Who are you this time, Princess?” Nightmare Moon demanded, sarcastically emphasising the title as she glowered down at her, her wings flaring up as she snarled out, “What name should I put on your headstone?”
“My name is Twilight Sparkle, I am Celestia’s Student.” Twilight replied as her shield flickered out of existence, its magic spent, “And the Guardian of Shadows. I won’t let you win. I can’t!”
“The last time you were an alicorn and even then, alone, you could not defeat me, you stand no chance now, little Twilight.” Nightmare Moon hissed, drawing up her magic for another strike. “You will die here and now, before you can seal me again! My Shadows will destroy you!”
Twilight’s world slowed down as the demonically possessed alicorn unleashed a wave of Shadows that would kill everypony present. She could not stop it. She knew she could not stop it. She was not strong enough, but she tried. She dragged up every ounce of magic that she possessed and then drew more from the puzzle, building it into a shield that would cover the ponies in the hall.
The Shadows hit it with the force of a hurricane and Twilight shuddered, barely able to maintain her protective barrier against the sheer weight and potency of the dark power she was facing. Her hooves slid backwards as the barrier shuddered and slowly retreated back from the force pressing against it. “I…I’m s…sorry…” She bit out to the ponies surrounding her as her forelegs buckled for a moment and she only just caught herself in time, “I…I can’t…”
“Die!” Nightmare Moon crowed, knowing she had won as she drove more of her power into the blast.
The shield buckled as Twilight did. The unicorn started to collapse as her shield started folding in on itself, unable to take the force of the attack.
Then the puzzle glowed brightly, surrounding Twilight in a golden glow as the same golden glow bolstered the shield and helped it hold. The ponies of Ponyville watched in shock as the glow took the shape of an alicorn and then died down, leaving a tall, proud, purple Princess in the place of the unicorn, her cutie mark the same as before, her mane and tail the same combination of three purples but longer and wilder, her wings badly torn and damaged and quite clearly unable to sustain flight, but sweeping gracefully along her back and draping over her like a noble’s cloak. She glared up at Nightmare Moon with narrowed ruby red eyes. “I don’t think so!” She snapped back, “You will not hurt anyone here!”
Nightmare Moon watched in furious shock as the other alicorn’s magic soaked up her blast and stood firm. She was not prepared for this battle. Not tired as she was from fighting the Sun Goddess. She had expected to sweep into the peaceful, quiet city and take over, not wage war with another Goddess in the middle of her victory speech.
She had the advantage though. The Princess before her was ground bound. The wounds that had occurred during the battle so very, very long ago seemed to have latched onto her soul and been carried over to the modern day.
Which meant that she, in this mortal frame she had stolen from the Goddess of the Night, could fly away and recover, while the Princess before her would have to walk to find her and burn up more energy, not really getting the chance to pull herself together before they fought again.
“If you think you can stop me,” Nightmare Moon crowed, “Come and find me. I will be at the heart of my old Kingdom!” With that she flapped her wings and lifted off, flying out of the window and into the night. Rainbow Dash broke free of Applejack’s grip and tried to fly after her, but Twilight did not get to see the result as her shield failed when the Shadows fled alongside the possessed Goddess and she collapsed, her wings vanishing and her form shrinking, returning to the unicorn she had originally been as her world went black.