Twilight Sparkle was relaxing in her brand new hammock, it had been three weeks since she had blamed all of her wrongdoings on Bob, and now she was sunbathing, despite the fact that her fur made it impossible to tan herself. Realizing she was just sitting in the hot sun for no reason, Twilight got up and walked back into her treehouse.
"Spike," she yelled.
"What is it twi-erm I mean Lord Twilight Sparkle, ruler of the seven dimensions."
"Good job catching yourself Spike, I didn't even have to hit you this time."
"Gee, thanks."
Twilight walked up to Spike and hit him upside the head.
"OW, what was that for," Spike asked, while rubbing his head.
"Just because I don't need to hit you doesn't mean I don't want to."
"But I didn't do anything,"
Twilight looked at Spike and then began screaming nonsense words at him, engulfing him in her magic and throwing him at a bookshelf. Before she could further lay the smackdown on his candy ass Twilight heard a knock at the door. She walked really fast to the door and opened it. On the other side was Rarity.
"Oh goodness Twilight, you simply must hep, the entire town has been engulfed in chaos, everyone seems to think there are changelings among us!"
"Wow, and to think we just stopped that evil Bob Saget, he probably would have gotten away with it too, if it weren't for us meddling kids, and that dragon."
"I was wondering if you knew some kind of spell to detect changelings, I'd do it but I'm just a normal unicorn, mmaking me the most pointless character on the show."
Twilight used her magic to pull down a satelite from space and crush Rarity with it.
"Thank you Twilight, you're a great friend," Rarity said in her dying breath.
"No problem," Twilight then ran into the middle of the rioting ponies and used a spell to amplify her voice," CITIZENS OF PONYVILLE, oh sorry, I had that set to Luna," Twilight flicked a switch on her horn," EVERYONE LISTEN, I KNOW THAT THE POSSIBILITY OF A CHANGELING ATTACK HAS INCREASES ANIMOSITY TOWARDS EACH OTHER, BUT DON'T WORRY,I WILL NOW CAST A SPELL TO REVEAL ALL OF THE CHANGELINGS."
Twilight channeled all of the magical energy she could muster, and then fired it at the entire crowd, spreading a bright light over all of Ponyville. When the light dissipated Twilight opened her eyes and looked on in horror.
Everyone had been a changeling the entire time.
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This story is totally canon.