When you come to Equestria for the first time, it's the first time you feel wrong-- not just unfortunate, or irritable, but utterly, catastrophically wrong inside in a way that can't be fixed. Your gut boils and your gorge rises. You can suddenly hear your heart beating, loudly, like a gong or brass pillars. Your mouth is dry and unpleasant.
For a moment, as you step through the gate, you feel like a monster. But again, as suddenly as you felt this way, you feel the opposite- this PLACE is wrong, and you've just had some kind of entirely natural adverse reaction to your environment. The air you gasp into your lungs feels at once thick and sweet, yet tarry and cloying. The unpaved road under your shoes slides gently in an entirely unnatural way. The colors are at once neons and pastels, a washed-out image that at the same time through an arcane process of some kind possesses unnatural clarity.
Your husband grabs you as you stumble at the horrors of this place, and you nearly walk back to get a refund for your ticket, hurl yourself on the return trip, Wayback Machine to when everything didn't feel so wrong. You manage to overpower this feeling, though, and you instead inform him of a sudden allergic reaction or something else you made up on the spur of the moment. He hands you an allergy pill, which you fake-take and later spit out into a rosebush.
As you come to meet the ponies- the inhabitants of Equestria, as everyone knows now since they backed their horsey plots out of thin air one day and set up tourism- the sensation gets even worse. You never really liked those equine little bastards, with their ridiculous utopian ideals (worse since they had actually achieved those ideals in every way) and their optimism and their names (Moon, Star, Twinkle, are they freaking Lucky Charms or something) and especially their insistence on naming everything after horse puns. Bad horse puns.
In person, this is the first time you've seen one, and the sensation of pure wrong you've been feeling from the land crystallizes around the pony tour guide, Star Bright. When she talks, it's bubbly and cheery and yet there's a static fizz behind it, like a slightly broken TV. Her eyes are brilliant and a bit too large and brilliantly bright, just like the colors and just like her name. She's got that faded-fluorescent feeling to her in spades. She grates against your nerves. Everything here has grated against your nerves so far.
After a while, in which you're shown around to things like Sweet Apple Acres (still a stupid name, and the apple sample they gave you tastes like sugar and acid in tandem), Sugar Cube Corner (the pastries are warm but they leave your mouth numb and the powdered sugar won't come out of your mouth) and the Books and Branches Library (the paper feels slippery and greasy in your hands).
You're observing yourself from outside, at this point. Inside, you know that you are being silly, that this is your old drug habit coming back, or some head trauma, or a possible averse reaction to the allergy pill that you didn't eat. You know that these are perfectly nice people, and that possibly, you're even the wrong one- you think the proprietor of the library complained about sweaty, greasy fingerprints on a book you remember reading.
But the you hanging outside knows that this is wrong. Something is wrong with Equestria. Everything is wrong with Equestria.
Out of your eye, you catch a glimpse of a dense wood, and the part of you that's still hanging around inside your head like a normal system of thought asks the tour guide what it is.
"That's the Everfree Forest," says Star Bright. "And we don't really go there. The weather acts weirdly, and so do the animals. And… it just doesn't feel right, I guess." Her spiky little horn shoots a tiny spark, unsure of itself. "Magically."
You decide that you want to go there.
Later, deep in the night, you take a walk under unnatural stars, to the forest that the ponies of wrongness believe is itself wrong. You figure either it'll feel like a normal place, or you'll be so disturbed by your apparent hypersensitivity to wrongness that you'll explode into shards of Who Gives a Shit. So when you get there, crossing the threshold, you're astounded.
It feels like a sudden rushing-away of reality around you, a feeling of icy cold running down your spine. Your vision flickers for a moment and valiantly attempts to display things in tricolor, then black and white, and then just white as it finally gives up the ghost. Your motor skills fade, after a few moments of desperate flailing, and after a few more instants of panic your sense of touch follows suit. You stop feeling anything but the white of the world, the prickly cold of the air forgotten. You bite your lip, but taste no blood. Taste nothing.
You have nothing to do here. And suddenly, like pumice in the bath, memories rise to the forefront of your mind. The time that you found out there was no Santa Claus- no big beard in the night, no savior for children. After that, when your kid sister died off the coast, God followed, trailing his imaginary omni-benevolence behind him. You grew up, and you learned that there was very little in the world that was magical, trailing to nothing at all. Pixie dust was the name of a drug, and "second star to the right and straight on 'til morning" led to a convenience store, complete with top-shelf porno. Truth and justice, like the others, big cons to make people feel better about themselves. There wasn't anything sacred. The world had no magic but that imagined to make you more obedient.
And now the ponies had the audacity to taunt you with their perfection. With their goddess that could be seen, and touched, who loved them unconditionally- more than a mother, but a queen, ruling with perfect foresight and eternal love. With their magic, that could save a child before they ever died, or the tame beasts that wandered around them never harming a hair on any delicate horse head. Hell, they could even fly. If the second star to the right was the domain of the Spectral Ponies, you wouldn't bat an eye.
In you, the voice that's speaking, though it's nearly drowned out by the envy and the hatred of these perfect little rats, tells you the Truth. Ponies are just like you. They're just as riddled with falsehood and corruption, with lies to children and magical absence. Their Princesses had to have some skeletons in their closets. They can't be this perfect. How, asks the voice, oozing with charm, echoing your thoughts and even your voice, would they ever do that? That's not how the world works.
You intend to prove it, you reply, and suddenly you are awake again, in the perfectly normal Everfree Forest- the forest that feels just like the rest of Equestria, mythos and fancy and disgusting sweet air, and your memories for the past few minutes drift away like smoke. But now there is something different. In you, you can feel something. Some strange enmity, blazing nuclear, indefensible, uncontained and fusion-hot.
In the distance, you hear a call, and then Star Bright gallops out of the town boundaries, relief obvious on her face. She begins stammering something about how she was worried about her human charges, and she'd like to get back to Ponyville soon, and then with your atomic hate burning in you like a beautiful, terrible second heart, you speak to the rampant evil of Equestria, hidden behind the surface, and you let it in, give it a home and then set it free.
Star glances at your grin for a moment, beautifully confused, and then her body begins to spark, glowing with thousands of malevolent golden strands tying her to the air. Each one is a perfect work of art, in its own way. As they glow, and Star Bright stammers out a "W-w-w-w-what?!", each bit of petrified starlight has the same question for you: Where?
"Second star to the right," you reply, in a hilarious, imperious voice, "and straight on 'til morning!" The light obeys, and Star is dragged off, look of horror and all, at massive speeds toward a house, crashing loudly into the roof of a building and obviously alerting some pony denizens before it speeds off into the night, followed by suddenly awakened pegasi.
You are star-stuff now, blazing, beautiful exposure to the realities of the world, and you have a new name for yourself, straight out of an ancient textbook about people who had brought the ponies woe. The name is a bit ugly, you think, but at this point, there aren't any more fitting.
So you call yourself Witch, and you leave to see about getting some of that Smooze stuff from the History of Equestrian Problems on your hands.