Suzy has a bad habit of existing in a person's life one minute and then disappearing the next, leaving no traces of her whatsoever. It's a habit she acquired when she was young - defence mechanism is what others might call it. In order to protect other people, including herself, she came in and out like a gentle breeze. 

That was the first mistake she made. 

The second mistake was... well, that's why this story was made.