Twilight Sparkle awoke to the unblinking turquoise eyes of the being who had once been her mentor. She was still lying where she had fallen. All of a sudden, she became aware of a roaring pain on the side of her head. Reaching up to touch it, she almost hit herself in the face, realizing just in time that she had no depth perception: She was blind in one eye. She started as the alicorn spoke.
"I am going to let you live, Twilight Sparkle." She paused a moment, as if to let it sink in. "After all, it was you who helped to free me of that-" She gestured to Luna "-and gain control of the most powerful being in all of Equestria." She paused another moment as if considering a few options, tapping a hoof on the ground thoughtfully. "I cannot, however, leave you to your own devices. There is no-one around to help you, and you have no wings." She eyed Twilight's horn with a sick smile. "And no magic."
She placed her hoof on Twilight's forehead, and purple energy flowed from the unicorn's horn into her own. Twilight slumped to the ground, unconscious for the second time in as many minutes, and the one who looked like Celestia turned and flew out the hole in the wall, passing over the rubble covering the lower half of Luna's body without a second glance.
***
Yes, she had been much weaker than her sister mentally: Celestia had not had a thousand years to try and struggle against the one who sought to control her mind. She had still seen everything that had transpired, of course. Her conscious had stayed confined in the deepest recesses of her mind, watching events occur through eyes that were not her own. The events that she saw through though eyes were those that chilled her the most.
She turned away from the piled rubble, walking out towards the railings at the edge of the once-garden. From there, she looked out over the city and beyond to the valley below. Somewhere out there was the remains of Ponyville, the first place to fall after Canterlot itself. It had received swift destruction: The spirits of the Elements of Harmony had not been given a chance to try and stop her. She had seen it all, powerless to interfere.
***
The white princess had come roaring down out of the clouds, landing with an audible boom at the beginning of the main road into Ponyville. A visit from Princess Celestia was rare in itself, but having her turn up unannounced and apparently alone was enough to have ponies crowding the streets. The mayor pushed her way to the front of the crowd.
"Princess Celestia! To what do we owe the honor of a visit from your highness?"
The princess had been standing with her head bowed and eyes closed for a few moments but now they snapped open, rage showing in the turquoise orbs. The mayor stepped back, a look of confusion and fear on her face, only to be halted by a solid wall of petrified earth ponies and unicorns.
"Harmony is finished," the alicorn said in a whisper, and energy flashed from her horn, streaking over the heads of the ponies and striking the town hall, rending it in two and setting it ablaze. She took to the skies, more bolts lancing out from her horn and striking buildings, creating an inferno surrounding the town. Dozens of pegasus ponies fly away from the flames, but two forms streaked towards the burning buildings. Loyalty and Kindness could not abandon their friends.
Celestia knew they perished in the flames. While she mourned and the other gave a triumphant grin, Ponyville burned.
"Now, none can stop me."
***
For all her form's ability, some mention of what had occurred managed to beat her to the next settlement the impostor visited. It was odd how fast the news traveled, Celestia reflected as she expanded her gaze to encompass the whole scene before her. Many other villages had been destroyed in this valley. The one wearing her form had come to each of them, expecting ponies to bow down before her.
Instead, she had been greeted with terror and flight. Each village that denied her had suffered the same fate as that of Ponyville, until such was her rage that she didn't even stop to announce herself, only bringing destruction and death before moving on. The sun and moon were forgotten in her bloodlust, the perpetual red sky of early morning alike in shade to that of the lifeblood spilled below.
Celestia turned away from the sad scene laid out before her, entering the building again through a different entrance. Soon she came to what had once been one of the most secure rooms in the castle, now open to anyone, though none but Celestia had seen the interior for millennia. Here the Elements of Harmony had been kept, ready for use in need but only able to be accessed by Celestia herself. Here, a choice had been put before her.
***
"BOW!" she screamed at the group of ponies before her, only to have them flee as all those before them had done. With a screech of rage, she sent bolts of energy after them. Through the haze of anger in her eyes, her aim was poor, and many of the bolts missed. A few, however, hit their targets and they fell, unmoving, to the ground. The alicorn muttered to herself under her breath.
"Perhaps Harmony isn't as worthless as I once believed. It is certainly something these foals seem to require," she said, spitting the last word out with a look of disgust on her face. "I will return soon," she announced in a booming voice, her words carrying through the whole town. "Perhaps, with a little persuasion, you will come to see the way things are now."
She took to the skies again, turning back the way she had come and flying toward Canterlot. As she flew, she sifted through Celestia's memories, the princess offering little more than token resistance as the parasite plunged deeper into her mind. It was more than she should have been able to offer, which caused the other to pause for a moment, before dismissing it. Celestia was clearly gaining strength, but once she had control of the Elements of Harmony-
"Ah," she whispered, a predatory grin appearing on her face. "So that's where you keep them."