Celestia and Luna quickly reached Canterlot, flying up to the tallest tower in the capital and landing on a balcony near the top. They entered a large hallway lined with stained-glass windows, a long carpet on the floor and an imposing door at the far end with a sun pattern painted over the center and a keyhole in the hub. Celestia trotted forward to the door, bent her head down and inserted her tip of her horn into the hole. Electric-blue light radiated from the hole and spread through the tips of the sun's rays. The door split open, revealing a gem-covered box on a dais.
The box floated out and the lid opened, revealing the Elements of Harmony. They floated out while Celestia glanced at Luna over her shoulder. “Are you sure about going with her to this alternate world?” She turned around. “This other Equestria needs help, yes. But Nightmare Moon's help? Wouldn't that be worse?”
Luna locked eyes with Celestia, holding a steady gaze. “If we use the Elements of Harmony on her, she'll be severely weakened and might not trust us. An ambush and attack is not exactly something that would engender cooperation.” She stepped up to her sister. “This other me, she will need all her strength to aid me.”
Celestia shook her head. “I don't like it.”
The box floated up to Luna's side, taken by the dark alicorn's telekinesis. “Neither do I,” she responded. She sighed and her wings drooped. “And I was to cut the ribbon to the Manehattan Train Station next week, too.”
Celestia bit her lip. She reached up with a foreleg and gently stroked Luna's back. “I'll have a talk with the officials and maybe push the opening date back,” she said, winking.
Luna glanced away. “No,” she said. “It wouldn't be right.” She trotted up to the balcony. “Come, sister!” she cried out, spreading her wings. “To the Everfree!” She leaped into the air, flying off with the box of Elements trailing behind, enshrouded in her magic.
Celestia rolled her eyes, but jumped up, following Luna across the sky and back to the Everfree Forest.
Nightmare Moon sat in the field, completely still save for her tail and mane. Her eyes slowly moved up to focus on a lone cloud floating above. “I can hear your heartbeat, pegasus. Come on down and talk if you're able.”
The cloud exploded into fragments as Rainbow Dash zoomed down, a multicolored contrail behind. The pegasus had a pair of saddlebags slung around her withers, each one full to almost overflowing. She threw out her hooves, skidding to a stop right above Nightmare Moon's muzzle. “Don't think I won't be keeping both eyes on you, Nightmare Moon!” She jabbed a foreleg at the alicorn. “If you try anything with my friends, I'll buck you so hard-”
“-You'll shatter your hind legs in the attempt,” the alicorn said, interrupting Dash. She arched an eyebrow. “What, do you really think useless posturing will impress me in any way, especially since we both know your threats are hollow?” She slowly stood up, smiling as Dash inched away from her. “Still, if you'd like to try, go ahead. You don't need your legs to fly, after all.”
Dash's lips curled back. She flew around Nightmare Moon's head and body, making quick changes in direction. “It doesn't matter, Nightmare Moon!” She flew up, stopping suddenly and turning around. She dove straight at the alicorn's back, stopping at the last possible second and flying around back to stare at Nightmare Moon's muzzle. “No matter what, I won't let you hurt my friends or betray them in any way!”
Nightmare Moon's body remained still, but a genuine smile crept its way across her mouth. “I see Loyalty found itself one quite suited to wielding it,” she said, her head slowly nodding. “I would still crush you in a fight, but there would be... regret at turning one such as yourself into a red mist. You have my respect, Rainbow Dash. At least in that regard.”
Dash's mouth opened for a moment. “Yeah, well... thanks, I think?” She cocked her head to the side. “So, even if you're from another dimension, the Elements of Harmony still feel the same?”
“At least Loyalty does, even though it's been a millennium since I wielded it,” Nightmare Moon responded. She broke eye contact with Dash, her gaze wandering up to the blue sky above. “I remember, long ago. Celestia and I wielded the Elements against all forces of evil. Discord, Sombra, the Smooze, Grogar and even the Changeling Queen herself fell before us. For a time, I felt at peace... and then the ponies betrayed me, casting me aside and my glorious night!” Nightmare Moon's wings shot out and arcs of electricity traveled up and down her horn. Her eyes turned white. "And they shunned me, turning away from my gifts and siding with Celestia, when all I wanted was appreciation for my hard work!” She focused on Dash. “Tell me, is it fair? Is it nice at all to do THAT?” she shouted, stomping the ground and cracking it.
Dash flinched at the stomp, but held her place in the air. She sucked in a deep breath. “It wasn't like that,” she said. “Princess Celestia tried to talk to you – well, the 'you' from this Equestria. But you, well the other --” Her eyes crossed slightly. “Oh, buck it this is confusing.” She shook her head. “Well, if my reality is as close to yours as we think it is, then didn't your Princess Celestia try to talk to you?”
Nightmare moon's head shot up. Her nostrils flared and she snorted, physically pushing Dash away. “You weren't there,” she stated, her voice unnaturally even. “How would it feel to you if everything you worked on, everything you slaved over was rejected? All those beautiful nights, all those jewels hanging in the sky. I did it all for the little ponies.” Her eyes faded back to normal. “And they stayed inside during my nights, waiting until daybreak and my sister's return.”
A slow wind blew through the field. Neither Dash nor Nightmare Moon spoke for a few minutes. Finally, the pegasus cleared her throat. “So... guessing you were also Generosity?”
Nightmare Moon's head slowly turned away from Dash. “I gave them all I could. I protected them, and they betrayed me and rejected my gifts.” She turned her head back, her mane whipping about like in a hurricane. “And now they suffer under the Tyrant Filly, while my sister lies at death's door.” The corners of her lips twitched, almost as if she wasn't sure whether to smile or frown.
Dash shook her head. “Yeah, they so deserve it.” She flew up, spinning around in a circle, gathering moisture and dust particles up. Within seconds, a small cloud had formed. She swooped up and over, doing a backflip before settling down on it. She stretched her forelegs over her head, but paused. She turned over and looked back down. “What was the other one?”
Nightmare's Moon's eyes flicked upward. “My 'other' what?”
Dash groaned, blowing out a breath and tousling her mane. “Your other Element of Harmony, duh!”
“Honesty.”
Dash blinked. She turned back and looked up at the sky once more. “That... makes sense.”