Mare of the Moon
"So, about that revenge thing," the Doctor said, trailing off with a sense of how ridiculous he sounded, hoping that Luna wouldn't overdo it.
"Responding to a punishment we shouldn't have received with a revenge scheme we both know will be ineffective is folly! We shall not engage in this jester's sport!" Luna exclaimed, the Royal Canterlot Speaking Voice in full swing. It would appear to the Doctor later that, perhaps, her time on the moon gave her some time to learn to moderate her vocal volume. While his conscience wouldn't dare question his decision to take Luna to skip her imprisonment, his ears were pleading to send her back. He couldn't hear them pleading, of course; even if he suffered from audio hallucinations, he still wouldn't be able to hear them over Luna's disturbingly powerful voice.
"But we have to make sure that the new ponies that wield the Elements of Harmony are fit for the job. It could be fun…" the Doctor said, his tone of voice all over the place, his ears ringing. He feared her overdoing the revenge plot significantly now. He wondered if this past Luna was even capable of not overdoing anything.
Ringing. Somewhere in his mind, the Doctor thought of ringing.
"What is that terrible sound?" Luna asked, her voice booming. The doors to the TARDIS shook from the noise.
The Future Luna was in a room deep in the TARDIS, and was trying very hard to get some sleep. Needless to say, it didn't work at all. She wished that she had royal power over her past self, but knew that the Doctor's warning existed for a reason. Still…She might have fared better had she brought some ear plugs.
Industrial strength ear plugs, Luna thought.
"That is the sound of my ears being annihilated by vocal tradition, Luna!" the Doctor screamed. He wasn't sure why after.
"No, not that, you silly colt! I'm referring to the sound of bells!"
The Doctor grabbed some ear plugs.
"I don't hear them."
"That's because you've placed things in your ears!"
Luna was almost at a volume the Doctor was comfortable with now. Almost.
"Bells, huh?..."
"Yes, Physician, bells!"
"I'm the Doctor."
"Somewhere located in thine TARDIS, Doctor, is a set of bells. And thine bells are ringing," Luna said.
"Oh. In that case…It must be my phone," the Doctor said, thankful that Luna had gained some reign over the volume of her voice.
The Doctor galloped over to his phone. On the way, he picked up a few objects that had fallen on the floor from Luna's audio assault.
He answered the phone.
"Hello, Doctor," a mischievous voice said. It sounded ancient, thousands of years old, and with a strange, almost hypnotic, charm.
"Dream Lord…" the Doctor said with anger in his voice. This was the fifth call he'd gotten since they took flight.
"I knew you could do it!" the voice said.
Dunnnnnnnnnnnnnnnnnnnnnnnnnn
"He hung up on me! I didn't even know the phone rang until a little while ago and now I find out that it makes a noise when I get hung up on! This is just marvelous!" the Doctor yelled with surprise.
"'Hung up?'" Past Luna asked.
"Ceased communication," the Doctor said.
"Are we arriving in Ponyville soon? We are getting bored on this ship of yours!"
"We're here now."
The Doctor breathed his first breath of fresh air in days. It was refreshing. Old leaves crunched beneath his feet; winter was rapidly approaching. It was the first steps from the TARDIS that were the best, he thought.
"Okay, so, tonight is the Summer Sun Celebration. I figure that since you are involved with the moon and night this is the perfect time to begin your revenge. Also, history more or less says it happens today, in," the Doctor said as he checked his watch, "2 hours."
"We still don't understand why this revenge scheme is necessary, Physician."
"It's the Doctor! Doctor!"
"My apologies, Doctor."
"Thank you. The reason for this, Princess Luna, is that we must make sure that the Elements of Harmony will be wielded by worthy ponies. The only way to ensure this is by testing them, and the easiest way to do that is to have you have your revenge on Celestia, which forces her hand on sending the little ponies to collect the Elements, which in turn ends your revenge, puts you on Celestia's good side, and keeps all the set points in time from changing. The way I see it," the Doctor said, a smile on his face, "Everypony wins."
"But what do you get from this?"
"I told you this earlier, Luna; I'm in this for some fun. Helping out a friend is also a pretty good factor. Maybe a bit of passive aggressiveness towards Celestia for breaking into my TARDIS, too, and the Elements of Harmony would be devastating if they fell into unworthy hooves. But the most important reason that I am helping you out, my little Princess, is that it would be a good thing to do."
"We're not little, are we?" Past Luna asked with insecurity in her voice.
"No. Just a bit younger than your big sister, that's all. Now, let's wreak a party!"
The Doctor led Luna towards where the Summer Sun Celebration was being held, running excitedly, knowing that this adventure would be one for the ages. At the very least, it would be interesting.
"Wait, no, I've forgotten something. Luna, hide somewhere. When you hear the whooshing sound, come out. I'll be back impossibly soon," the Doctor said, rushing back to the TARDIS. He had an order to make, an order that had to be placed years in the future, to avoid suspicion.
"Doctor, why are you leaving us?"
"I need to get you a Nightmare Moon costume! You'll need it for the Summer Sun Celebration!"
"Why do you have to go in the box, Doctor?"
"There's only one pony who can make something convincing enough to pull this off! And she is one of the six!" the Doctor yelled back to Luna. He had to hurry; otherwise he might have forgotten where he put his money. He didn't have enough gems for a trade.
He dashed into the TARDIS.
"Old coat, it's the old coat, it's the old coat, it's the old coat, it's the…" he repeated to himself, hoping to jam it into his memory for just a moment longer, just the few precious seconds he'd need to send his wonderful blue box on its course.
5 years. 45 feet to the left, 6 inches down, tilt of 93 degrees, moderate speed fade, lights flashing, chameleon circuits still broken, filters still active, instant translator unneeded, crash detectors on, brakes still on. It only took a few moments for the Doctor to program all of these settings into the TARDIS's controls, still chanting about the old coat, until he pulled the switch, the big switch, the switch that sent his madpony's box off to another time and another space.
Whooooooooosh
He was off.
He ran over to get his old coat. It was inside of the chest by the double doors, which he was incapable of opening in the proper direction. He opened the chest, snickered to himself about how great it was to have so many things that were bigger on the inside, and grabbed his old coat out of a pile of clothing items. On his way to the current home of his monetary worth, he displaced or tossed aside a few scarves of varying length, a few old sonic screwdrivers, an old diary, his severed hoof (inside of a preservation jar), a few hats (including a fedora, and the ever-cool fez and Stetson), and his time travel trousers.
He carefully picked up and unfolded his old coat, which was still a bit precious to him. The problem with regenerating is that one's whole self changes, the worst part of which was that the Doctor no longer had wings to fill the holes in the top of his coat, rendering it (at least temporarily) useless to him. Still, it was rather nice. He reached into the pocket where his old sonic had resided, and pulled out a wallet.
Not too many coins, but enough to pay the clothes-maker.
There was a loud thud, and a big thump as the TARDIS landed. A few things shook, and the Doctor rolled onto his back from the impact. He got up off of the ground, quickly brushed himself off, stored his old coat, and walked out of the TARDIS.
"I think I've done it again!" the Doctor said to himself as he walked into Rarity's workshop, hoping that she had enough materials to make Luna a suitably convincing Nightmare Moon costume.