Keep in mind this is still in editing and is a little rushed. I wrote it all last night. I'm posting this so you can vote and edited it a little bit because I decided it needed it. I hope you guys like it, and for those who don't have amino you can vote while actually knowing Coco's story. Apologies that it isn't written in the best...word choices, I was very tired. Basically copy and pasted it and edited the one part that I wanted to. Now, onward!

     Basically Coco wasn't always evil, she actually was best friends with her current worst enemies: Amour and Queen Rose. She had a fairly great life, even had a husband. She just had no plans for kids, just felt no need for them.
     Her husband, Stitch, was slowly falling in love with Amour, however, without her being aware. And she found something else that contributed to her fall to villainy: two powerful gems. She at first just thought they were beautiful gems and brought them home, but after being startled by Stitch on one occasion she zapped the gem and it hit her back with a different spell, making her study both gems and figure out both were magic.
     Being the good friend she was, she gave one to Amour. She thought Rose was powerful enough and was closer to Amour anyways. Amour was somewhat concerned about the gems as Coco tried to explain all the good they could do with the magic. Though Amour kept the gem, she had her doubts and had an uneasy feeling. She wore it around her neck to keep it safe, not wanting it to get into the wrong hooves.
     Two days later, Stitch divorced her. He claimed he loved Amour, and that he wanted to remain friends with Coco because he didn't dislike her at all, he just lost the spark of love he had. Coco was absolutely heartbroken and outraged at him, especially because Amour got with him afterwards (but she hadn't cheated, she had waited till Stitch had divorced her).
     Blinded by bitterness and rage, Coco took the gem she had and put it on. It gave her a somewhat horn, though she couldn't display true magic like a unicorn. It had limitations. She could only do certain magic, and it would tire her. The process of gaining this horn was excruciating, she gets headaches thinking about it.
     The magic of the gem had corrupted her spirit, the bitterness in her heart had blinded her senses. Coco was not the pony she once was, she was not herself. She was now power fueled and hungry, and ready for more. She stormed to the castle, where Amour, Stitch, and Rose were happily dining. She lit the castle on fire, fought and toyed with them a bit by separating them, then raced off. She was not ready, the mare had to gain strength. The fire had killed Stitch, though Amour and Rose survived.
     Amour decided to keep the gem mainly to help protect the land. She learned to use it correctly, and wasn't corrupted like Coco. Every time she uses it she thinks of her, and she hopes to one day free the poor mare from her rage. In truth, Coco is just a pegasus trapped in her own blind rage.