While at
mishymoocow's place on Tuesday, read Jon Ronson's
The Psychopath Test: A Journey Through the Madness Industry, a highly readable, and often amusing, lay encounter with madness and dealing with madness.
Some of it, however, is chilling. Such as the story of a researcher interviewing a psychopath and showing him photos of expressions of fear. His response:
I don't know what that expression is, but it is the one people make just before I kill them.
That would be a case of
zero empathy then.