It was another normal Friday in Ponyville. At least, it was for the mailpony, Derpy. Sure, everypony else was all excited about the Summer Sun Celebration in a few days' time, but that didn't do anything to her mail route. She had it down to a science.
Cover the main street, then drop off something weird at Sugarcube Corner. Swing around down the street which had the old library on it, drop off some kind of package at the clock repair shop. Pick up a clock, deliver it to the owner. Visit Sweet Apple Acres and Carousel Boutique, then finish it off by trying (and failing) to do a cool stunt at Rainbow Dash's cloud house and diving down to Fluttershy's cottage.
Derpy's life was simple. Eat, sleep, deliver mail, get mocked for eyes, repeat. Every single Friday. This particular Friday, it appeared that Rarity had won some sort of lottery. Derpy liked Rarity, she never mocked Derpy's eyes, and was always giving gifts to others.
When it was time to visit Rarity on her mail route, she came with extra glee, accidentally hitting a flagpole with her wing. For once, it didn't fall down! This also made her smile. She knocked on Rarity's door. Rarity opened it, and almost squealed at the package and the letter attached for the lottery winnings. As she left, Rarity tapped her on the shoulder.
"Oh, and Derpy, would you be a dear and see if the mannequins I ordered have come in yet?"
"Why of course, miss Rarity, when I've delivered this package to miss Rainbow Dash, and this one to miss Fluttershy. They're nice, like you."
And with that, Derpy left. Now what stunt would she try today? She was getting pretty good at the corkscrew, where she'd spin towards the house, drop off the mail and skim the cloud until her wing hit it and she would go down like a metor to Fluttershy's house. Yes, that's what she'd do.
"Wheeeeeeeeeeeeeeeeeee-aaaaaaaaahhh-ohnoohnoohnonono-aaaah-" CRASH!!
Yep. Always worked.
Back at the depot, she saw a huge package come in with Rarity's name on it. She supposed this contained the mannequins she was asking about earlier, and took it upon herself to drag it to Carousel Boutique. On the way, she passed Time Turner, who was waving some kind of glowing-stick-thing around.
"Here ya go, miss Rarity! It was just coming in when I got back!"
"Thank you! Here, do you want to come see what they can do?"
"Sure, miss Rarity!"
So they entered the boutique, mannequins in tow. Rarity opened the package, and began assembling them. She explained why she was so excited: "The special thing about these mannequins, dear, is that they are posable, with a come-to-life spell!". Derpy read the label on the exterior: Nestene Plastics, unicorn posable! Odd name, Nestene. Probably just some kind of in-joke with the bosses of the company, or something. Derpy turned around, in time to see Rarity animating it. She posed it in the way that Applejack sometimes stood and smiled.
"If it's okay with you, dear, I'm going to go fetch an outfit to put on display on this!" Rarity walked away, happy as could be. Derpy felt something tap her on the shoulder. She turned around, fully expecting to see Rarity. It was the mannequin. Derpy screamed.
"Run!" It was Time Turner! What was he doing in the boutique? He never wore anything but that ridiculous black jacket, and it never needed patching. She decided his advice was sound, anyway, and began running.
"Time Turner, what's going on?"
"They're being remotely controlled!"
"Yeah, by miss Rarity."
"...Oh. That makes things a bit more complicated. It appears that our friend Rarity is working for the Nestene consciousness."
"Hang on, the package for those mannequins said 'Nestene' on it."
"I would advise keeping her away from plastic. Something made her 'Come to life' spell permanent. They're using her as transmitter. Oh, and it's The Doctor, not Time Turner." Suddenly, somepony screamed from inside the boutique.
"Miss Rarity!" Derpy cried, rushing into the building. "Stay away from the plastic!"
The Doctor knew Something was wrong about all this. Using another pony as a transmitter was possible, but they'd need a secondary transmitter to do it. Something organic, something containing knowledge, something which had some sort of lens... something nearby. Well, maybe Derpy would know something like that. He was new to the town, and she wasn't, after all. Maybe she'd even be able to come... no. No more loss meant nopony to lose.
Rarity was not okay. She was being attacked by some beast made of coat hangers, and her horn was apparently on the fritz, as the only spell she could cast was the Come To Life spell, and she didn't see how that could help.
"Miss Rarity!" A grey blur swooped at the beast, faster than she had ever flown before. She threw the beast, and everything else made of plastic, out of the room, slamming the door. "Seal it, quick!"
"I-I can't... I can't cast anything but a Come To Life spell..."
Suddenly, out of the shadows came Applejack. Derpy liked her, she accepted people for who they really were. Derpy smiled and waved. She heard a thump and went to go block the door.
"Applejack! What were you doing down here?"
"SugarcubeRarityHon, I was looking for you!"
"Really? Was my scream that loud?"
"SugarcubeRarityHon, did you forget about that new line of mannequins you wanted to show me?"
"O-oh yes, right. Sorry, but we are in a bit of a predicament."
"Message from Celestia." Was that a northern accent?
"Not for us, surely."
"We seem safe right now, SugarcubeRarityHon"
"Message from Celestia!"
"Not now! Applejack, your voice sounds funny whenever you say my name."
"What are you on about, SugarcubeRarityHon? I'm fine!"
The Doctor chucked the envelope at the head of 'Applejack'. It sunk into her 'stetson'.
"Oh alright, DoctorTime TurnerWhooves, you got me fair and square!"
The letter shot straight back at The Doctor's head. Upon second thought, this was a bad idea... A REALLY bad idea.