Canterlot... For centuries, Canterlot was the shining gem of Equestria, the pinnacle of pony society. Now, it’s a reminder, a bleak and monolithic warning to the world. 

Changed by the chemical and technological poisons that plague the mountain, an abomination of nature, I wander the greatest disaster Equestria has ever seen. 

... I will escape eventually, and when I do, I hope my friends still see me as Twilight Sparkle, and not the monster that hides among the ruins. 

There was only one explanation. For all of it. All of the strange, erratic behavior. Her irrational fear of the sun. Her nocturnal habits of locking herself in in the dark and closing all the blinds. Wearing her sunglasses everywhere, even inside! It was time to invest in some silver, garlic, and a wooden stake.