She knows that she is damaged, after all they've done to her. Like the puppet with one arm at the flea market, which no one wanted.
"I told you", her mother had said, "who wants a damaged toy?"
And now it's her no one wants. When people look into her eyes, they do not see their own, clear reflection. She's like a broken mirror. Shards everywhere, used to protect herself, to hurt. Their images are twisted, more true than reality, closer to themselves than their reflections.
They leave her alone, and finally she is safe.
Broken mirrors can do magic.