My name is Julie, and I am 17 years old. I know that seems like I’m a lot older than you, but I’m really not. I still like to play outside and eat candy, so nothing really changes as you get older.

Somewhere between childhood fables and adulthood’s hard-earned cynicism, we all learn a painful truth: Not everyone is good to us. Some take advantage of kindness. Others mistake it for weakness. And ...