What is going on with her?

I met this person who seemed to bully me on the spot and make fun of everything I say and loves to talk about me behind my back. This past time I asked someone to have her come to talk to me so I could call her out. But, instead she went to talk to someone nearby and I could tell she was talking about me behind my back again.
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I forgot to add that I don't even know her really at all and right from the get go she was like this.
What is going on with her?
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