Who is this? [ongoing]

Gale was living an average, regular life. She was generally quiet, got good grades at South Yoylen High and slipped under the radar. It isn't until a mysterious girl comes to school that she breaks her monotonous life.
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This is a BFB fanfic, but it may be hard to tell since the characters are humanized and have different names. Also, the side characters (like Evelyn Whelk) are not really inspired by BFB characters unlike Gale and Sylvia.