There are some scary people around. People who hurt others casually, and without remorse. These predators take what they want, using charm, wits, and a lack of any empathy. We call them psychopaths, sociopaths, malignant narcissists, or trolls. Are they mentally ill, or are they a sub-species of human? How can we identify them, and how can we stop them doing so much damage? Based on years of fi...