"Ladies and gentlecolts, I present to you Princess Luna, your new ruler!"
Luna listened to the roar of ponies cheering at her sister's announcement. It felt like hours had gone by as the noise level finally dropped, instead of a scant few minutes.
She made her way through the throng of ponies, shaking a hoof here and there while following Celestia. Slowly but surely, they made their way over to the hall designated for the reception where she would finally have a chance to mingle with her new subjects.
The party was in full swing when Luna and her sister arrived. A soft melody was playing in the background. Many ponies vied for her attention, but she only had eyes for one pony. She made a beeline for him but took longer than she would have preferred, accepting several pony's congratulations. He was sipping experimentally on a drink several ponies were handing out. She saw him make a face at the taste as she approached. Eventually, she came to a stop in front of him.
"Doctor, it's time for that dance," Luna said victoriously, a smile quickly escaping her neutral royal expression.
"Uh, about that," the Doctor muttered. She saw him glance over her shoulder, and felt a familiar presence just behind her.
"I distinctly remember my saying that you were banished from Canterlot for all of time, Doctor," Celestia spoke.
"Whelp, I didn't exactly intend to stick around either," he replied. Luna broke into the conversation as her sister opened her mouth again, hoping to assuage her sister.
"I invited him, sister. He shall enjoy tonight's party in Canterlot at the very least." Celestia was in full Princess mode when she turned to her. The last time she had turned this face on her was when Luna broke her favorite stained glass window, when she thought that it hid a secret passageway. Unfortunately for her, it hadn't.
"A word, Princess Luna?" Her sister calmly asked her, suggesting no possibility that she could deny her request.
Demurely, she followed Celestia as she walked over to a nearby vacant corner. When Celestia was sure they were far enough away from everypony to be overheard, she rounded on Luna angrily.
"Luna, how do you know that pony?"
"He is the only pony, save you, that I have ever trusted completely." Celestia looked at her worriedly.
"Now that's more like it!" The Doctor's voice broke out through the audience, and the two quickly turned towards the commotion. The Doctor had corralled several pony waiters together, and a large audience was gathered around him. He held a long, skinny yellow fruit above his head and he quickly cut it up, throwing the tiny pieces into the drinks around him.
Luna turned away from his antics and saw Celestia staring questioningly at her.
"Oh, don't give me that look, sister. He is the most unique pony I have ever met. I know that I can trust him." Celestia sadly shook her head, as if she were remembering a long distant memory.
"You do not know the Doctor, Luna," she slowly said. "Do not presume to think he has your best interests at heart. He will lie to you if it he must."
"He is trying to help me, sister." Celestia laid a hoof on her shoulder reassuringly.
"I am sure he is. But wherever the Doctor travels, death always follows in his hoofsteps. Do not think you are safe, if the Doctor is around." Luna looked away sadly. Celestia did not understand. Her sister sighed helplessly at her stubbornness. Celestia begrudgingly pulled her hoof away from Luna's shoulder and stepped back towards the celebration.
"He may stay, for now. it is your party after all. Let's go enjoy your celebration, Luna." Luna's smile grew in wonderment. She had seen her sister give in so easily. Maybe the future would be more enjoyable than she had dared predict.
The festivities had continued without them. The audience had grown larger around the Doctor from the last time she had looked. She pushed her way through the ponies who congratulated her when they realized who the rude pony was. She broke free of the excited crowd to find the Doctor.
He was dancing unlike any other pony she had ever seen. He stood on his back legs and danced about, waving his forelegs above his head. Several ponies had begun to imitate his crazy antics, and many more would have joined them if Luna hadn't grabbed the Doctor.
"To be honest, I only came here for the dancing," the Doctor said as the group around them slowly dissipated. She pulled him towards the dance floor, and went over her favorite dance. Luna and the doctor slowly waltzed around in a small circle, ignoring the other ponies that joined in on the more traditional dance. It was very intimate, but Celestia's warning weighed heavily on her mind.
"Doctor," Luna asked. "Who is after me?" They danced for several more beats before she heard his response.
"You can't know that, Luna," the Doctor sadly told her. "Her name wouldn't mean anything to you anyway. But I can tell you that I'm here to fix it. She's been messing with time. History says none of this was ever supposed to happen."
"Well, history is wrong for once, and I would not have it any other way. One may tolerate a world of demons for the sake of an angel." she added, blushing slightly. Their dancing came to a halt as the music moved on to a new tune. Many ponies moved away from the dance floor, letting others take their place.
"May I have this dance?" Celestia had appeared by their side just as the song ended.
"Of course, sister. Go ahead." Celestia pulled the Doctor away, leaving Luna alone. She had to know what they were talking about. Luna followed them discretely as the two danced, hoping to learn where her sister had met him.
"You shall stay away from her, Doctor. If it weren't for the coronation, I'd have already-"
"It's not my fault. I've been swept up by events." Luna saw her sister glare at the Doctor. 'But I will depart as soon as I am able."
"Why are you really here, Doctor? What is so important that you would think to ignore my warning?"
"It's about Luna. About her future. She-" They moved away, and Luna lost sight of them as more ponies joined the dance. She pushed closer, hoping to hear their conversation.
"-And it will happen. But some pony's trying to change what can never, ever be changed. It's a fixed point in time. It has to happen."
"What has to happen?" Luna demanded. The Doctor and Celestia turned slowly towards her.
"The Doctor was just telling me," Celestia glanced at him quickly. "That he had urgent business elsewhere."
"...Yes! I figured something out about your pursuer. I have to go investigate!" He flashed a grin to Luna before turning back to Celestia. "Thank you for the dance, princess."
"Goodbye, Doctor," Celestia calmly answered.
As the festivities continued around them, Luna watched the Doctor make his way to the exit. He glanced around before slipping through the door into the hall. She quickly followed him out the door. Her hooves clopped along the empty corridors until she found him standing by the recess beside the throne room. He stood there waiting for her.
"Doctor. You're not telling me something. What is it? What's on the other side?" Luna finally asked the question that had been on her mind for a long time.
"You're right," he apologized, turning away from her. She knew it! What horrible truth had he been hiding all this time?
"I'm not telling you something..." Luna waited for the Doctor to explain what he had been hiding all this time. He ran a hoof along the edge of the mirror distractedly.
"It's a spacial-temporal hyperlink spell," he admitted.
Finally! "And what is that, Doctor?" Luna hazarded a second question, hoping this more open nature of the Doctor would not close shut after his first honest answer.
"No idea," he continued unashamedly. "Just made it up. Didn't want to say 'magic door'."
"So it IS magic? And what is on the other side of this 'magic door'? May I go through?" Luna asked excitedly.
"No! It's not very interesting where I come from anyway." Luna ignored his warning, rushing into the opening while his back was turned. She heard his voice as she stepped over the threshold. "Luna, wait!"
Luna emerged from the castle into an empty desolate wasteland. She saw several makeshift structures laying around the entrance she had passed through. She shielded her eyes from the bright glow that shone upon the land, and looked for the source of such a powerful light.. She was awestruck by what she saw above her.
The sun was much brighter here, and it revealed a world above Luna. It was closer and larger than the moon she raised every night in the sky, and she could see green patches amidst a sea of blue.
"This is your world, Doctor?" Luna asked, her breath taken away by the beautiful sight.
"Trust me. You don't want to know." Luna felt the short burst of illumination begin to fade. She had to know more. She reluctantly took her eyes off the beautiful world above her, and looked at the Doctor as he held his hoof out.
"Tell me anyway, Doctor." He motioned through the doorway, back towards her world, as he searched the surrounding area carefully. She stepped onto the familiar floor as he finally spoke.
"...It's the moon. Celestia used it as a prison for a pony who tried to overthrow her." Luna laughed. Surely he must be joking. Celestia banishing a pony to the moon?
"My sister has never done something so unjust to anypony!" The Doctor failed to see the humor in her joke. Luna's laughter slowly died as she saw his sad stare.
"No she hasn't. But in the future, a pony will betray every thing she stands for. She'll bring chaos and destruction to Equestria before Celestia stops her. And your sister will banish her for a thousand years."
"No pony should deserve that," Luna solemnly declared. "I won't let my sister do such a horrible thing." But Luna had her doubts. Celestia would never do something so cruel. Could she?
"I know when she'll make her move," the Doctor spoke as Luna walked towards him.
"When, Doctor?" Luna demanded, his warning quickly forgotten.
"Some time when princess Celestia is far away from you. That pony who's been following you has been watching you for most of your life, but couldn't do anything with your sister so close. So now that you're princess, Celestia might travel somewhere and leave you vulnerable."
"Why can't I just stay by my sister? I would be safe then."
"Even if you try, there will come a time when Celestia has an emergency to deal with and leave you here. It will happen eventually. But it could be years before she shows up. I'll take the shortcut and meet you then." The doctor pushed on the mirror, and it swung open.
"Remember, she'll make their move when Celestia isn't by your side. She won't do anything right away if you keep her occupied. That will give me plenty of time to find you." She nodded sadly. Luna had hoped he would wait here, but Celestia had been more cross than she had ever been when she saw him.
"Then I shall take the slow path." The Doctor walked to the other side of the mirror, onto the moon itself. His parting words squeaked through the closing door.
"Good luck, princess Luna. And... thank you for the dance."
And so the Doctor her left once more. Even though the future looked dangerous and uncertain, she would live for the day that she could meet him again.