Pinkamena Diane Pie is Pinkie from another universe. But she doesn't remember what her old life was like, or why. She regrets what she has done--but what has she done? She has a goal, but she doesn't know what it is. She has no memory, or friends, or defense. But maybe this can be a good thing?
Pinkamena sets out to find out who she is, or at least remember what happened. Armed with the friendship of the ponies she meets along the way, her old pain is forgotten, and happiness fills the gaps.
But deep inside, there is a dark secret that must never be remembered.
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Pinkie Pie was living the life! She loved life, her parties, her happiness. But when she is suddenly transported to a new dimension, a dark life full of hatred and war, she has to start all over making friends. The ponies she meets now are ones that aren't as kind as she's used to.
But she has her own defense. She has knowledge stronger than Twilight Sparkle, more than even Princess Celestia. She knew this would happen, and she knew why. And she could help them in her new dimension. The only thing is, if they will follow her lead...
She has two choices: Try harder or...give in.
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(Picture is NOT mine, I just added text to a different picture, credit in image source)