They met on a moon.
"So, your sister banished you here as well?" asked Morgana, staring into space with a frown of concentration.
"Doest thou also have a sister?" Luna asked in return, looking at the strange creature she sat beside. The only similarity between them that she could see was the wings, but even they were different. The creature didn't appear to have any hooves, or a coat, or even a tail, although thankfully a garishly purple mane was in evidence.
"Yes. Kayle," said Morgana, a low growl underlying her voice. Her eyes continued scanning the starry skies. "And why do you talk like that anyway?"
"'Tis the fashion of my home..." said Luna, but without much conviction. Her face fell, and she looked down at the moondust where her hoof drew meaningless patterns. "We royals are meant to speak in this manner."
Morgana blew out her lips derisively, still not looking at Luna. "You're a royal, are you?"
"Indeed: my sister and I ruled together, until..." Luna trailed off.
Morgana finished for her. "Until she betrayed you."
"No!" Luna burst out, faster than thought. "At least... I hope she didn't."
Morgana looked across at the horse-like creature. She'd been surprised at first, of course, but only by the novelty – after having been in the League and seen such monstrosities as Cho'Gath, a dark blue talking horse with wings and a horn (which reminded her strangely of that obnoxiously calm Ionian; the one with the sickle) was practically mundane by comparison.
Right now, Luna was looking away from Morgana, biting her lip in a mixture of doubt and regret. Morgana's eyes narrowed and she let out a deep breath by way of drawing the horse's attention.
"Let me get this straight. Your sister received the love of all your subjects, despite the fact that you shared the burden of ruling your land equally between the two of you, and when you chose to stand up for yourself, she cast you out and seized power for herself."
"It wasn't like that!" Luna protested, but Morgana was the better liar here. "I... I went too far. I used my power to become something frightening, and dangerous."
Morgana smiled a twisted smile. "Right. Did you even hurt anyone?"
"Well... um... I made night everlasting."
Luna was taken aback when Morgana cackled out loud.
"Oh, please! That's the worst you can manage? If you're going to fall, you could at least have the lack of decency to fall all the way."
Luna's temper snapped – she rolled away from the coatless creature and summoned up her anger. It had seemed like such a crime the first time, but... well, what could she lose now? She closed her eyes, letting the Nightmare's influence overtake her.
Morgana looked on as the transformation took place with a kind of amused detachment, akin to the expression she'd seen Brand wear the first time he encountered Annie's fireballs.
Veiled in a whirlwind of darkness, the small horse grew over the still-seated Morgana. The great wings burst out, dispelling the darkness, and there stood a black-coated mare with a mane made from the night itself, her eyes seethings pits of vengeance.
Morgana clapped, slowly, three times. "Very pretty. Does it come in other colours as well?"
"What makes you think you stand any chance against me?" Nightmare Moon hissed.
Morgana stared Nightmare Moon straight in the eye.
"I would kill my sister. Without hesitation, I would plunge a blade into her heart; strip her soul from her body. Looking at you, right now, I know you wouldn't do the same to the one who betrayed you. She proved her supremacy over you, and you don't even know that she beat you. Your sister may be a traitor, but right now I have more respect for her than you... weakling." This last word was uttered with such venom that, had Morgana spat afterward, it would almost certainly have seared flesh.
Nightmare blinked. "You... You would... kill her? This Kayle?"
Morgana nodded. "What's more, I'd enjoy it. My only regret is that, once I truly do kill her, I won't be able to do it again."
Nightmare looked away. "I... I've thought to myself that I wanted to kill Celestia, but... I wanted to believe-"
"What? That she would forgive you? Don't make me laugh." Morgana returned to scanning the skies, her furious frown back in place. "Once a bond as close as sisterhood is broken, it can't be repaired. Tell me: did you ever want to leave your sister? Did you ever say that she was no longer your kin?"
"...No, I... Never."
"Mine did. She disowned me. And when I escaped to another world to get free of her once and for all, she had to follow me just to make sure I didn't have too much freedom." She let out a bitter laugh. "Just to remind me of how much she hates me... Just because I didn't go along with her plan of how things should be."
Nightmare looked down at where Morgana's forehooves should be. She had things like claws, which she was balling up so tight that they were surely cutting into her own flesh.
Morgana looked back up at Nightmare with startling abruptness.
"And your sister did the same."
"She banished you here. Does that sound like something that a sister would do to her sister?"
Nightmare opened her mouth to speak, but there was nothing to say. She slowly sank to her knees.
"...Your sister," said Nightmare. "Did she banish you too?"
Morgana smiled humourlessly. "Not quite, although she had a hand in it. I thought I had a chance to kill her one day, and took it... and she was able to use this incident to convince those more powerful than me that I should be removed. But I'll find a way back. No matter how long it takes, it was worth it to get so close; I actually saw her blood, and the flash of fear in her eyes..." Morgana's smile showed teeth, her eyes glazed over looking back through time.
There was a moment of silence.
"I need to get back too. Perhaps we can help each other."
Morgana looked across at the black mare.
"To help one betrayed by her own sister? Certainly. We just need to find the right stars..."
"What do you mean?" Nightmare asked, brow furrowing in confusion.
"I come from a reality beyond this one. The alleged reason for my initial banishment was my seizing of powerful and forbidden magic – forbidden exactly because it was powerful – so I think it's fair to say that I know a few tricks. I can work a way out of here if we can just align the right stars around this moon."
Nightmare smiled. "That happens to be one of my areas of expertise. But even then, it'll take a long time. Stars don't move easily."
Nightmare gave the equestrian equivalent of a shrug. "I can't tell yet. But it will take years at best."
"Hm." Morgana pondered this. "Well, I was banished eternally, so I can only assume that I'm not meant to age and instead slowly decline into insanity on this forsaken rock."
"Same here. But we'll show them."
Nightmare stood again, flexing her wings. Morgana looked around at her, smiling slightly.
"Oh? Is the horse finally showing some steel?"
"My name is Nightmare Moon. Strangely fitting, considering," she said, scanning the skies. "We're going to be stuck here for some time getting those stars into place, so we might as well get along."
Morgana nodded sideways. "Morgana."
"Charmed." Nightmare smiled crookedly. "And perhaps, since we've so much time together, you could teach me something..."
"How to hate," said Nightmare. When she looked at the fallen angel then, Morgana saw something.
"So... do you really want to see your sister – Celestia – strewn on the floor, gasping for breath as her lifeblood seeps from her?"
Nightmare swallowed, then nodded. "She betrayed me. There's no going back from that."
Morgana grinned. "There might be hope for you yet, Nightmare."
Morgana reached a hand up to Nightmare – one wing lowered, supporting her as she rose to her feet.
She dusted off her skirts casually and stood, proud and unbowed.
"No mercy for the traitors. Sisters that were; sisters that are no more. They will die. No matter how many years must pass, we will see it done."
Morgana set off for the nearest ridge, but stopped to look back, confused as though remembering something forgotten.
"What happened to the little blue horse?" she asked of Nightmare. "The one who called itself Luna?"
Nightmare's voice was cold; as cold as the void around them. "She is as dead as Celestia will be. There is only the Nightmare – now, and forever."
Morgana showed her teeth again. "Come, sister in betrayal: we have some stars to find."