As the last of the debris crashed to the floor there came a shout from beyond the ragged hole that had been the doors of the throne room. A squad of ponies burst through the swirling dust, their coast dull as shadow, their obsidian-black armour gleaming in the fading light as they spread out into the hall, rolling over the dazed guards.

A cry rose up from behind the throne as a fresh contingent of the solar guard thundered into the room: "Protect the princess!"

They surrounded the throne, eyes fixed on the advancing enemy and spears lowered in magical fields. Yet rather than attack, the black-clad soldiers halted half way into the room, forming a line that bowed back toward the shattered door. They glared at the solar guard, but made no effort to attack. In the confusion a strange silence fell as the two sides regarded one another.

Celestia rose from her throne.

"Normally I ask ponies to knock," she said quietly as she took in the view, the same quiet smile that she always wore growing just a fraction as one of the dark soldiers shifted uncertainly, his eyes flickering to her face. "If you have a petition it would be answered far faster by registering with my secretary and–"

"Still deflecting your fear with humour, Celestia?" The voice that cut off the solar princess echoed strangely in the broad space, taking on an ethereal, ghostly harmony with itself as it filled the throne with a short, hard laugh. Anyone watching Celestia might have wondered just how the skin beneath her white coat managed to turn a lighter shade of pale and might have assumed it was merely an illusion, but there was no mistaking the fear and recognition in her eyes.

She took a step toward the edge of her dais, her eyes fixed on the door as a fresh cloud of smoke began to pour through, creeping along the floor, its tendrils curling up around columns and ponies and anything else it encountered. A dark figure stepped through, wreathed in a black mist that seemed to fold over its body like a cloak. Its – her – eyes were closed yet she navigated the floor with regal ease, setting one foot before the other as if she had trodden the same path every day of her life. The dark guard accompanying her separated to allow access through their lines before closing up to surround the newcomer.

"You always told the better jokes," the dark pony said, raising her hooded head. "You were always the trickster."

The newcomer threw back her head and laughed, her cloak collapsing into a cloud of mist as she spread her wings wide.

"Nightmare Moon," Celestia sighed. She closed her eyes just as the dark princess opened hers.

"No, it is I; I am myself," Luna replied, though her eyes narrowed to slits as she spoke. Luna licked her lips and took a short step toward the throne. "Surprised to see me?"

"Luna, please don't do this to us again. I lost you once, I—I can get the elements, the—"

"The Elements of Harmony," Luna sneered, a deep laugh rising up and burst from her throat as she half-turned from the throne. Her head shook. "Do you think I did not have those baubles neutralised this time? Did you truly believe they changed me in any way whatsoever?"

"Luna..."

"You know why I'm here, sister." Luna's hoof crunched against the marble floor as she turned, surrounding itself with a filigree of cracks. She lowered her head, pointing her horn directly at Celestia's face. "Where is she?"

Celestia's chin rose a fraction. "Safe. Far away."