(Note: I'm generally not a fan of nonfiction "self-help" kind of books, and I very rarely recommend them, but I think everyone should read The Gift of Fear, by Gavin de Becker. Here's a pretty good review of it, and trust me when I say that it puts violent behavior in a different context than that most of us are used to thinking in.)
However, from a "writerly" standpoint, I couldn't help but be struck by how useful Chapter Four, "Survival Signals" could prove to be to someone who is writing a book that features a character with less-than-honorable intentions towards another person. The chapter outlines some of the methods which can indicate that a person is a predator. These include:
Charm and NicenessUsing the word "we" to indicate that two people are on the same side. This makes it difficult for the victim to say no to whatever the predator is requesting.
In the words of Red Riding Hood from Into the Woods, perhaps the ultimate victim, "Nice is different than good."
Too Many Details
Anytime a person lies, s/he tends to fill his/her story out too much with more details than are necessary.
Applying an undesirable label to another person in an attempt to get him/her to agree with what you want him/her to do. In our Red Riding Hood example, the wolf might say, "You're probably too snobby to pick flowers for your grandma, anyway." Red Riding Hood's response? "No, I'm not!" It's easy to prove she's not snobby, but not so easy to catch up again when the wolf has run ahead to eat her grandma.
Performing some unasked-for task, only to subtly demand something in return, afterwards. The guy who asks you if you need help loading your groceries in the car is an obvious example.
The Unsolicited Promise
Anytime someone who is over the age of 12 says, "I promise," take a moment to wonder why.
Discounting the Word "No"
It may seem obvious, but no means no. Unless you're a bad guy who doesn't want to listen to it.
Seriously, if you're having a hard time with a "bad guy," try reading parts of this book. And even if you're not, you should read this book anyway.