Celestia shivered in the moonlit wasteland that the Royal City had become.

Her armor, hammered gold and mother-of-pearl, was icy against her coat. Her breath puffed out in front of her, but it was hard to inhale, as if there weren't enough oxygen in the air. She could hear the few royal guards that had volunteered for this battle panting behind her.

"Remain behind us until we give thee the signal," she murmured. They were sheltered in one of the many markets. The well-kept forest that wound through the city was dead from lack of sunlight, and the bare branches didn't provide much cover. "Thou knowest just how dangerous the creature is."

There was a murmur of assent. Celestia took a deep breath, not that it made much difference, and moved towards the castle.

The clink of metal boots seemed horrifyingly loud in the silence. She tried not to wince, instead keeping her head held high and her wings spread. Her heart was pounding in her chest. She had to hide her fear, her sorrow, her guilt.

Angry. She should try and look angry.

It wasn't hard once she saw what the demon had done to their--her palace. Stained-glass windows that had endured for hundreds of years were shattered. Turrets had been toppled. The dented, blood-stained helmet of a Solar guard hung above the main gates. Celestia felt a stab of true hate. A golden aura, brilliant and alien, surrounded the helmet, and yanked it down. She ran a hoof over the tattered crest on top of it, and glared into the depths of the palace. She thought she saw a flicker of ghostly blue, somewhere in the furthest reaches of the darkness, but it might have been her eyes playing tricks on her.

"Nightmare!" she roared. It fell flat in the thin air. "Thou hast stolen our honored sister, the Princess Luna, from us! Thou hast imposed Night Eternal, and slain the green things of our land! Murdered ponies in our service! Disrupted the harmony of Equestria! Thou hast issued a challenge, and lo, we rise to meet it! We are Princess Celestia, Regent of the Sun, Keeper of Harmony, Beacon of the South, Guardian of Those Who Walk in the Light! Face us in battle, monster!"

The last echoes of her battle cry died. There was silence for a long time, so long that the mares and stallions behind her had begun to shuffle their hooves nervously. Even Marble Bow, the captain of her Guard, was beginning to get restless. The carved wooden box on his back tilted, and the Lunar guard standing next to him nudged it back into position with one glossy black wing. Celestia remained perfectly still, wings spread wide, the muscles of her neck beginning to ache under the weight of her helmet.

Finally, mocking laughter rang out. Most of the guards jumped, but Celestia managed to remain stoic.

"The Solar Princess herself?" somepony laughed. "We are honored."

Suddenly, the interior of the palace lit up. They could see directly into the throne room, where a tall black alicorn stood proudly on the dais that had once held the throne of the Princesses. Her razor-edged wings were spread in a parody of Celestia, her horn blazed with harsh, silver-blue light, and her dragon eyes were narrowed in malice. She flashed Celestia a chilly grin, exposing tiny fangs.

"Step forward, then," she called. "If thou truly intendeth to challenge us, sister."

"Thou art not Luna," Celestia said through gritted teeth. She stepped forward, into the castle, and the guards followed her. "Thy reckoning hath come for thee, demon. Prepare thyself to meet the Creatress."

"We are terrified." Nightmare Moon smiled savagely.

Celestia stopped in the middle of the throne room. Moonlight poured in through windows no longer covered by shadow magic, dwarfing the golden light that her horn gave off. Small chunks of the throne lay scattered everywhere. She raised her violet gaze to the Nightmare's sea-green one, as she flicked the primary feathers of her wings. The guards drew their weapons with a rasp of metal against metal.

"We offer thee a choice," Celestia said stiffly. "Take thy leave now, and return Luna unto us, that she may lower the Moon and end this madness. We shall not pursue thee in this event. Dost thou accept?"

Nightmare Moon's mane glittered. "We do not."

"We did not expect thee to," Celestia said calmly. She closed her eyes and bowed her head, forcing power into her horn. Her magic was weak, since the source of it had been gone for so long. But hopefully, it would be enough to--

Without warning, a wave of icy, malevolent magic slammed into her, knocking her off her hooves. She struck the ground hard, feeling several delicate bones in one wing snap. She screamed as agony flooded through her. The aftereffects of the spell rebounded off of her own magical boundaries, burning like ice. She shuddered at the all-permeating cold, and cried out again, weaker this time. The cold Lunar magic seemed to be eating away at everything inside of her, leaving her empty. A void.

Celestia opened her eyes. She became aware of the screams of other ponies, and raised her head.

Two guards, one Lunar and one Solar, lay crumpled and broken at the base of the dais. Silver-blue magic still flickered around the edges of their wounds. As she watched, Marble Bow shrugged the wooden box off of his back and wrapped his amber magic around the hilt of his sword. He charged the Nightmare, the other surviving guards close behind him.

Blocking out the bolt of fear that the sight brought her, the bone-chilling cold, and the pain in her injured wing, she ignited her horn and concentrated.

A golden partial-dome of magic appeared in the air in front of the charging ponies just in time to deflect another spell. Then it flickered and disappeared. Bow skirted the dais, dashing around behind it during the brief time that the Nightmare was distracted. A Lunar guardsmare, who looked vaguely familiar, kept pace with him. Everypony else scattered, scrambling for strategic positions in the spartan throne room.

Celestia struggled to her hooves, one wing dragging. She tried to get a handle on her faltering magic, desperately wracking her brain for what she knew of combat magic.

"Princess!"

She looked up just in time to see somepony sheltered behind a particularly large chunk of throne toss her a sword. She caught it in her magic without thinking, and turned to Nightmare Moon, who hadn't moved from her spot on the dais. She was sending lances of Lunar magic out into the seemingly empty room, and she didn't see Celestia as she approached with the sword held high.

At the last second, she turned, a whip of cold energy trailing from her horn. Celestia caught it with her sword, the blade glowing briefly golden as she sliced through it. With her uninjured wing held out for balance, she lunged forward, aiming for just above the Nightmare's breastplate.

A booted hoof slammed into her wing, forcing the broken bones to grate against each other, and a flare of magic darted in between her horn and the sword. With the bond broken, the weapon clattered to the floor. Celestia yelped in pain. She horn flared and she shoved the demon away with all her strength, just as Bow and his Lunar companion leaped onto the dais with their swords at the ready.

Nightmare Moon growled, pushing Celestia off the dais and spinning to face the new threat.

"In the name of the Sun!" Bow bellowed, sweeping his sword towards her vulnerable knees. The Nightmare seized it, yanked it out of his magical grasp, and tossed it aside. Before he could retreat, or his newfound partner could come to his aid, she picked him up in a cloud of silver-blue magic and calmly flung him through one of the few windows that glass remained in. A stylized picture of Celestia raising her Sun shattered.

Celestia yelled wordlessly, concern for the stallion coloring her tone, and her horn blazed directly above her eyes. Crescent-shaped blades of golden light slashed at Nightmare Moon's hindlegs. Blood that looked black in the moonlight spattered on the stone, and she turned, howling with rage and pain. The Lunar guard spread her wings and flew after Bow, casting a panicked glance back at Celestia.

"How darest thou?" the Nightmare snarled.

"How darest thou?" Celestia countered, mounting the dais. "Thy quarrel is with us, not our servants!"

"Thou brought them. Our quarrel is with thee and thine both because of thine own choice."

"Thou shalt not harm them, demon!" Celestia shouted, punctuating the last word by locking horns with Nightmare Moon. She glared at the other mare with pure hatred. Her eyes were so similar to Luna's.

Thou art not Luna.

Not Luna.

Not Luna!

"We shall strip your foulness from our honored sister's form, even if it kills us," Celestia murmured, searching the Nightmare's eyes.

She just laughed, and what felt like bands of dry ice closed around Celestia's horn.

All control she had over her body and her magic dissolved, draining away into a concentrated form of the same savage cold that had assaulted her earlier. Her legs buckled, and as her broken wing hit the stone, she tried to cry out. But her mouth wouldn't cooperate.

She could move only to shiver, in the grip of the violent Lunar chill. Above her, Nightmare Moon laughed again.

"Squirm, sister, squirm," she taunted. Celestia's teeth chattered as she stepped over her, finally moving off the dais. There was a flash of light, and one of the guards cried out.

Celestia closed her eyes, trying to block out the hideous cold, and the way that her armor rattled against the stone. She hadn't been able to make contact with her Sun since Luna had been taken in the grip of this malevolent spirit and refused to lower the Moon. It was the source of her magic, where she drew her power from. Heat, brilliant light, diverse colors and the frenetic activity of life--that was Celestia's power. There wasn't a lot left, but she reached for it anyway, a Sun-bright coal at the very bottom of her reservoir. As soon as she released it, the cold began to ebb. She opened her eyes and hauled herself to her hooves, running off the dregs of her magic.

The Nightmare strode through the center of the room, leaving a trail of broken and dying guards in her wake, Solar and Lunar alike. One Lunar stallion lay curled into a fetal position near the dais, hissing in pain. A vicious cut in the membrane of one wing was crusted with ice. Celestia leaned towards him, hoping that her legs would hold her.

"Can you walk?" she rasped, abandoning the formal speech of the nobility for the easier peasant slang. She felt she was justified. Her magic was nearly gone, one wing was broken, and she was on the verge of either weeping for the guards she had brought into this or screaming at the Nightmare in pure hate. She hardly felt like royalty.

"I believe so, Princess," he replied wearily, climbing to his hooves.

"The box." She nodded to the carved wooden box, still lying on the floor where Bow had left it. "Please. Bring it to us."

"Of course." He gingerly folded his wings against his armor, then bolted for the box.

Celestia cringed as Nightmare Moon turned towards the sound of galloping hooves. The guard had already maneuvered the box onto his back, wings holding it in place, and was turning to hurry back to Celestia. The Nightmare's eyes settled on him. Even though she didn't have any magic left to defend him with, Celestia spread her unbroken wing in a challenge.

It made no difference. Ribbons of power, razor-sharp, spiralled out from Nightmare Moon's horn. Celestia screamed a warning, but it was too late. One of the ribbons caught the guard directly above the withers before he was halfway to her, neatly severing his head. The box tumbled to the floor as his body crumpled, and she screamed again, barely aware of power that should not have been there stirring in her horn.

It burst into golden light before the last traces of the Nightmare's magic had faded. The box clattered against the floor next to the guard's headless body, and was then engulfed by the light. It shattered, and the Nightmare squinted, shielding her eyes with one wing.

Two crowns flew towards Celestia, one smaller than the other, each inset with three gems. The frames surrounding the jewels dissolved before they reached her, and they hovered in the air around her, spinning in a slow circle. Celestia closed her eyes and felt the steady energy of the Elements of Harmony. They were like old friends, comforting and strong. Their unique magical signatures welcomed her own.

Nightmare Moon's furious voice cut into her brief moment of peace. "It is impossible! The Elements cannot be wielded by a single mare--"

"We warned thee, monster!" Celestia interrupted, her furious voice echoing off the walls of the throne room. "Thy time has come!"

The power readily flowed into her when she called it. She felt her hooves leave the ground, and leveled her horn at Nightmare Moon. The demon threw up her wings to protect herself, but it was no use.

Six beams of brilliantly-colored light flowed out of Celestia's horn, weaving together on their way to her target, and she went with them. She washed over the screaming Nightmare, swirled around her, searching for weak points. Places where she could begin to separate the spirit from her sister.

But there were none.

Celestia's search became more frantic as Nightmare Moon writhed in her prison of rainbow light. She couldn't find anything find anything useful. Luna had been well and truly trapped by this being, and she couldn't reach her. In fact, if she didn't know better, she would say that her sister had willingly bonded with the foul spirit. But that was impossible.

Luna! Luna! Canst thou hear us?!

There was no answer, and Celestia felt wetness on the cheeks of her physical body. She couldn't free her sister. But she couldn't allow the thing that had possessed her body to continue terrorizing Equestria. So many had died already, from the initial attack, and the battles in which Luna's own guards had flown against her, and the cold and the lack of oxygen and starvation as all the plants died. She could not bear to bury anymore soldiers, anymore citizens. She couldn't lead her country through another day of Night Eternal without breaking. The weight of their fear and hope was too much for her.

She made a decision.

The rainbow condensed as Celestia drew back from it and poured more power into it, immobilizing the mare inside it. It spun in the center of the room, growing paler and brighter. Celestia opened her eyes and watched it, holding it steady with her horn. It spun faster and faster, shrinking and lengthening into a spear of bright light, and then...it shot upwards, leaving a neat hole in the roof of the throne room and a lingering scream of the Nightmare's.

The moon sank at a fantastic rate, but not before shadowy new features had appeared on its surface.

The jewels floating around Celestia fell to the ground, suddenly colorless. She sagged, barely keeping herself from collapsing, as something that had become a distant memory in Equestria poured in through the windows. Sunlight.

"My Princess!" The cry drew her attention to the front of the throne room, where Bow was striding in with only a slight limp. The Lunar mare walked beside him. "We are victorious! This day belongs to the Sun!"

She stepped off of the dais. She couldn't remember ever being this tired before.

"Indeed," she said quietly, passing him as she made a beeline out of the palace. "We have orders for thee, Marble Bow."

He saluted. "Anything, my Princess!"

"Gather the dead, and bring them to our encampment. We shall oversee the burial rites."

With that, Celestia stepped out into the sunlight. Her armor felt too heavy, but she didn't care.