"He's dangerous all right." Father said it in a musing way. Then he chuckled. "But not to us, my dear In fact, I don't think you ever had a safer man in your house."
This is one of the first statements anyone makes about Shane. Joe's perception in Chapter 1 is insightful and proves true. The quote itself sets up the dichotomy that is Shane—dangerous yet safe at the same time. The rest of the book attempts to explain that dichotomy, exemplifying the situations in which Shane is dangerous and in which he is safe. Basically, Shane is only dangerous if someone has wronged him and/or threatened him, but when that happens he is not just dangerous, but deadly.