I have an opposite story.
There was this shy, ugly girl in school that no one wanted to be around. She was new, so I attributed it to that. Me and another friend spent quite a lot of time getting to know her, spent time with her etc, and it seemed to be going fine. Until it all went to shit, that is.
It seems like she was a compulsive liar, and told horrible things about us to her family and random people in general. I have no idea what things out of what she said were true, or if it was all made up.
One day, her grandma went to pick her up, and she pretty much cursed at us, and babbled complete nonsense, while the "friend" encouraged her. I was so appalled you could do something so malicious to an old, innocent lady, that's even related to you.
Apparently that was the reason she switched schools. She did so again 2 years in.