Luna was, for the first time in three months, in control of her own body. The last thing she remembered was accidentally touching the Element of Chaos, or more specifically the element that represented Anarchy.
Because she had once worn the Elements of Harmony, coming into contact with any one of the six elements that represented Chaos caused an imbalance of her magic, resulting in the dark half of her powers as the Moon Goddess to go out of control.
Had she known that was what the jewel that foolish noble had given her, she would have thrown it into the deepest pond in her garden.
Looking around, she quickly realized her situation.
She was banished to the moon. For how long, she did not know, but it would be quite some time before a new bearer of the Elements would be ready to deal with her dark side.
Good thing she was immortal.
Two Hundred and Fifty years later...
Luna was bored. This was not an unusual state of mind since she was banished. About the only one she could talk to was Nightmare Moon, who apparently was a bit of a pervert.
She always knew reading those smutty romance books would come back to haunt her.
She decided to go pester Nightmare again, since the two had taken to playing pranks on each other to kill time. Celestia had never figured out how she created that weird pocket space, and Luna didn't feel like explaining it.
If Celestia had known that all Luna did was throw it onto the dark side of the moon, she might not have sealed her sister up there. Then again, after a hundred years she had already read all the books she had borrowed from Starswirl (more than half of his library, to his amusement. He had given her all of his personal books the day he died, having no apprentice that he could trust with them), the ones from the castle library (almost all magic tomes) and most of the food she had stolen from the kitchens had been eaten. Thankfully for her sanity, she had also stashed every single prank item she had yet to use there as well, or she would have lost her mind decades ago.
So yes, she had become quite bored.
"Back again, little Princess?"
"Nightmare, drop the foreboding tones. For Equestria's sake, I'm the only one up here aside from you! And how many times have I told you to just call me Luna?"
"Oh, alright. Spoil my fun will you."
"Thank you. So what do you want to do today?" asked Luna.
Before Nightmare could answer, she noticed something.
"What in the hay is that thing?" she asked, pointing a long hoof in the direction of the shadow.
Luna turned her head...and stared. The thing was freaky, to say the least...not to mention really familiar.
It was entirely black aside from two sickly yellow eyes...and it felt wrong, very wrong. Almost like it wasn't alive.
"What in the hay?" said Luna going to get a better look. Nightmare put her hoof on Luna, stopping her.
"I don't know what that thing is, but it feels dangerous. It certainly isn't anything I recognize, and most creatures can't handle the moon without magic."
Luna racked her mind trying to remember where she had seen something like it before. Then it hit her! She had seen it in one of Starswirl's old diaries!
She used her magic to teleport it the one she remembered seeing it in...and gasped.
"What? What is it?" said Nightmare. Luna hovered the page over to her.
"... You have got to be kidding. This thing is a more dangerous version of those blasted changelings, only it can't change it's form?"
"Close enough. According to Starswirl, that thing is called a Heartless. Unlike Changelings, however, it doesn't feed on love, but on hearts themselves. He said that they actively hunt hearts and that the only thing known to put them down permanently to free the hearts taken was something called a Keyblade. Magic could be used to get rid of them temporarily, but regular pony magic wasn't very good at it."
"What kind do we need? Because I think that thing sees us," said Nightmare.
"Let's see...the spells the strange pony who explained things to him helped him with this new magic...and here's one! Blizzard!" said Luna.
Icy cold magic gathered at the tip of her horn, and narrowly missed the Heartless. It screeched in anger, and started to run at them.
"It didn't work! Are there any others?" said Nightmare in concern.
Luna pushed the book to her dark half, and Nightmare tried her luck.
Lightning magic gathered on Nightmare Moon's horn and blasted the Heartless. She clearly had much better aim. Unfortunately, the heartless wasn't alone. Dozens more sprang up out of the shadows of the dark side of the moon, and it was all the two could do to blast them with this new magic.
Nightmare seemed to have better luck with it, and her spells definitely had more power behind them. Luna found a healing spell that she was very good at.
When the last one faded away for the moment, the two nearly collapsed. They had cast more magic than they had ever done before, and they were out of practice because of the administrative position Celestia insisted they take in order to lighten her own workload.
"That was horrible..." said Luna.
"Agreed...and if that book is true, then this is only the first wave."
"We can't let them get onto the planet... I'll put up a barrier spell to keep them out while we sleep," said Luna, her eyes dropping.
"I'll help..." said Nightmare.
The two touched horns, and a pearly-white barrier appeared around them. The two collapsed on each other, leaning into the other for support.
Hopefully they would be awake when it broke...
Falling. They were falling.
She could sense her other half next to her. The two finally land on a platform floating in the darkness. The platform was odd...like stained glass. It was a dark blue color, much like their coat. On the top were the phases of the moon with a mare on it...and on the bottom was Celestia. You could see her profile on the glass, one front hoof in the air, the other bent at an angle. She had her eyes closed and her Cutie Mark was there for all to see. Inside most of the circles were bright stars. Her wings were fully extended.
Beside her was Nightmare Moon, only she was wearing a black armor as opposed to her silver one. She had an obsidian crown that was identical to her silver crown, down to the crescent moon at the top.
"Where are we? What is this place?"
Welcome, Twin Princesses. This is the Station of Awakening. Here you shall decide whether your world is protected from the heartless until your return, or whether it shall suffer the way almost all worlds have suffered under the attack of the Heartless. Fail, and only your Elements of Harmony shall allow you to escape. Succeed, and your next 750 years should prove most entertaining as you travel worlds until your sentence is up for review.
"Who are you?"
I have no name. I am simply one who chooses those who have a chance to wield a Keyblade and defend the realms. Now, Princesses of the Moon, chose your path. Shall you walk in the Light, or travel the path of Darkness?
Luna looked at Nightmare. If she hadn't given birth to her dark side, she might have blindly walked in the light. Nightmare was likewise having a dilemma, because she didn't want to be at odds with her lighter half. The two looked at each other, and in a show of unity walked between the two paths, revealing a third one that had been hidden.
So, you two would chose to walk the path of Twilight as a balance of both darkness and light. How very interesting. To walk the path of Twilight means that you shall share both light and dark, though one nature shall be more dominant in the other. You, Luna, shall have more light in your powers while Nightmare shall have darkness. I suppose it is fitting, considering the two of you were once one and the same. Now, little Princesses, chose a power. You must forsake one for the other here.
A staff, a shield and a sword appeared.
The two walked towards the staff first.
The staff of balance. Wisdom and knowledge await those who wield it.
The went to the shield next.
The shield of glory. The power to take any wound and come back again and again without injury.
Finally the sword.
The sword of the Moon Fang. Unbridled potential that is only matched by the darkness that seeks to devour.
To which do you chose? Shall you take the staff, forsaking the sword? Chose the shield, forgoing the staff? Or will you take the sword, and forever loose the shield? Choose wisely...
Luna looked at Nightmare. Then she asked "Is it possible for us to chose our own paths? So that we may cover the other's weakness?"
You are two beings, yet the same. It is acceptable for you to chose a different path, or you could choose them all. Really, the two of the three option is just our standard requirement. There is no actual rule saying you have to choose only two.
Nightmare turned to her lighter half.
"Personally I'm more in favor of all three. How about you?"
"Me as well, though I do favor that staff and sword."
Nightmare looks up at where she presumes the voice is coming from.
"We choose all three."
The ground beneath them shatters, revealing another platform. Before them were grotesque versions of themselves, and what Nightmare can only assume were the forms born from the Element of Anarchy.
Be forewarned, young princesses. To walk the path of Twilight, both light and darkness must coexist. To shun one will spell the end of both. For as the light grows, so does it's shadow.
Luna and Nightmare summoned something with their horns, their wings flared out.
Beneath them, a shadow merged and grew tall. It was horrifying and reminded Luna and Nightmare strongly of King Sombra from the Crystal Kingdom before it was lost. It was pure darkness, and it didn't have a heart.
Before them were a pair of swords. They were long, thin and appeared to be key shaped. Luna had a deep black sword with a light silvery-white edge. At the bottom was a short chain that had a diamond white crescent moon at the bottom attached.
Nightmare had an identical sword, only the coloring was reversed and the moon at the end was a deep onyx black in color.
They looked quite sharp.
At some unseen signal, the two charged at the dark alicorn creature that gave them such a chill. They found jumping easier, even without their wings, as their swords allowed them to float. Their attacks caused a great deal of damage to the creature, and eventually they heard the voice again as the thing slowly dissipated.
Congratulations, little princesses. Very rarely do we see anyone other than homo sapiens survive the Station of Awakening. Truly you are a credit to your kind. However, once you leave this world, you shall have to change your forms a bit. I am afraid talking ponies are only common in Equestria.
"Will we ever come back?" asked Luna.
So long as you call this world home, and wish to return, eventually you shall come home. But you will not be able to override the banishment that was decreed by the Elements of Harmony for at least another 750 years, so unless you want to just come and gaze upon your home from the moon...
The voice didn't need to elaborate. Clearly they wouldn't be able to set hoof in Equestria for a long time, so they may as well explore other worlds. Nightmare had one last question though...
"Just out of curiosity, can we leave anything we pick up across worlds on the moon like we did in Equestria, or will we have to stop and drop it off?"
Making a storage space here, in your domain, is simple enough. And your little trick of leaving things on the dark side would keep unneeded questions from occurring. I suppose you could just call the moon your 'home base' as it were. Though there is a limit to how much you can leave here, so try to keep it reasonable. Like say...roughly the size of your palace in space?
Luna looked at her dark counterpart with a wide grin.
"You know what this means don't you?"
"Yep. Hello library," said Nightmare with a smirk.
Luna and Nightmare awoke to find the barrier gone, but a new necklace around both their necks. Luna had a silver necklace with a diamond crescent moon, while Nightmare had a platinum necklace with an onyx crescent moon.
"I suppose this means we need to reorganize this space, before we leave."
"Right...I'll get the pranks and everything else and you get the books. It shouldn't be too difficult to create a space under the dark side of the moon," said Nightmare.
As the two went to collect all the various knicknacks that had gotten scattered over the two and a half centuries they had been stuck there, they didn't notice that a space had been created until Nightmare tripped over one of the key holes.
"What in the hay... Luna, come over here!" she yelled.
"What is it?"
The two saw the key shaped holes in the dark side of the moon, in a spot that was perfectly positioned to avoid any sunlight. The two grinned, summoned their new Keyblades, and opened up their new storage space.
It was an underground palace, though you couldn't tell that from the ceiling. There were two large windows, one facing each direction. One was aimed at Equestria, and it had a massive telescope aimed at the planet. The other was aimed at space, and it had a telescope that was aimed at the nearest world. The two quickly moved everything in before they explored the place.
Luna was immediately delighted by the fact that as soon as the books touched the library floor, they flew to the shelves and were neatly filed according to title and subject. Nightmare found a moving picture room, which when she popped in a disc-shaped object started to play some sort of picture with sound and color.
It took them ten years to get used to the place and figure out most of the rooms. The place was so interesting that they forgot about traveling the worlds until boredom set in again. It had taken that long because they had killed time exploring, dealing with any Heartless that tried to bother them (the things were like parasprites...they kept coming back for more!) and looking at Equestria or any worlds that caught their interest.
Finally, Nightmare grew bored enough that she tried to teleport from one end of the underground castle to the other...and ended up creating a portal by mistake. She poked her head into in, saw the world beyond it, and immediately grinned.
Once informed of the incident, it was all Luna could do to get the new clothes ready. They had appeared without warning in the large wardrobe and it didn't take a genius to figure out that it was for all the outfits they would wear off the moon. Whenever they summoned their Keyblades they would be given some sort of armor that had a mini-skirt under a dark blue sleeveless dress with a red collar that had a single white line in it. It had at least three bows that were light purple, and many crescent moons on it. She also had a white choker around her neck with the diamond crescent moon in the center. Her boots were light purple and just barely cleared her ankles. Around her wrists were white gloves with blue linings. On her back was a cape and her wings could be hidden at will.
Needless to say Luna was quite confused as to why the clothes appeared, since ponies generally didn't wear anything unless there was a big event planned.
They took one last long look at Equestria, before summoning a new portal and vanishing into thin air. Down below, Celestia wondered why the moon seemed so much brighter for a moment before the form of the Mare in the Moon seemed to fade a bit.