ShadowMist knew that she was early for her now seemingly weekly meetings with Luna. She expected Luna to already be in the garden, but as she landed near the wall and looked around, she couldn't catch sight of her.
"Luna?" she called lightly. "Princess Luna?" she called again, a little louder.
She decided the only thing to do was wait. She stayed near the back wall, exploring around near it. She'd been in the garden several times, but there always seemed to be something new to see. It was rather large, after all. She began examining the nearby plants, trying to figure out what they all could be—but she was no botanist.
ShadowMist had been staring thoughtfully at some flowers on a bush, but she turned as she heard Luna's faint hoofsteps close by. "Hello again!" she smiled. ShadowMist was feeling surprisingly chipper today. Maybe it was because she finally had a friend, one who trusted her and who perhaps, in time, ShadowMist could trust as well. She reached down to pick one of the flowers for Luna, but as she did so the mare broke into a run, rushing towards her.
ShadowMist looked up in surprise, not having time to react. Her back slammed against the back wall, and Luna's hoof pressed against her neck.
"Lu....na....." ShadowMist breathed. She felt the hoof on her throat, pressing harder against it so that she couldn't breath. She felt it loosen suddenly, and then press down again, harder. It was as if Luna was fighting...against herself. What was happening?
And then it hit her. There were two options...but ShadowMist was in favor of her second theory. One, Luna had turned bad again. Or two...Nightmare Moon was back. Somehow, someone, controlling Luna, right now.
Her fears were confirmed as Luna spoke. "Luna's not here now." she smiled, but it wasn't the same friendly smile the ShadowMist had seen the previous time they'd met. There's was something different, off, about it. It was unsettling, the way that her eyes now seemed to bore into ShadowMist, and the way the smile seemed so happy to now be choking her against a wall.
And the voice. It wasn't Luna's voice she heard. No, the voice that came from Luna's lips was cold and smooth, thick with malice.
ShadowMist focused on trying to breath. The hoof on her throat remained, no longer wavering it had in the beginning. ShadowMist looked into Luna's eyes desperately searching for the pony she hoped was there. But she felt dizzy, and the world began to spin as her brain was deprived of oxygen.
Reflexively, ShadowMist kicked her legs in a last desperation, her body fighting for the resource it needed to survive. The spinning turned hazy, and dark around the edges. Then ShadowMist felt the hoof against her neck shudder, Luna was trying, trying. Everything inside ShadowMist screamed for breath, but there was no air.
Nightmare Moon didn't let go until ShadowMist's body stopped moving. Then she let it drop to the ground, and unmoving heap of black against the bright green grass.
Luna stood, shocked, looking down. Nightmare Moon's hold slowly drifted away, and Luna was left alone.
"CELESTIA!" Luna yelled, knowing full well her sister couldn't hear her. She paused for a moment, debating leaving ShadowMist alone. But time was precious now, and Luna across the garden, still calling for her sister. She made her way through the castle and burst into the throne room, her hooves pounding against the floor.
"CELESTIA!" she yelled when she saw her sister at last. There Celestia sat, as usual, regally on her throne, taking care of the day's business. She, and the few guards in the room, turned suddenly as Luna burst in.
"Celestia, you have to help me!" Luna's breath came in gasps. "In-in the garden." she choked out. She couldn't hold back, and tears began to stream down her face. She turned, not waiting for Celestia, and raced back to the garden.
Luna reached ShadowMist's body, still laying where she had fallen. Celestia came up beside Luna, and she looked up at her sister, pleading in her eyes. "Please Celestia! I've never asked you for something as important as this. You have to bring her back! I can't, you know I can't! Please, just do this one thing for me! PLEASE!"
Celestia looked from Luna to the body. She didn't say a word, but placed her horn on the Pegasus' side.
ShadowMist lay unmoving on the ground, Celestia's horn glowing and pressed against her.
Luna tried to calm herself. Everything was going to turn out alright. She smiled.
Then Luna jerked back, fighting off Nightmare Moon. Death was nothing to smile about. Luna pushed against Nightmare Moon, barely keeping her at bay. She backed up, shaking her head, mentally fighting off the darkness that wanted to consume her.
All of a sudden, Luna felt a weight pull off her, and she was herself again. Tears once again formed in her eyes as she realized what she'd done. The only pony that had ever tried to understand her, her one friend in all of Equestria....was dead. The Nightmare had killed her. And yet Nightmare Moon was still Luna. Luna had let it happen.