Watch your back! … How to spot and identify demons and other subversive spirits … And what to do next. Demons, fairies, and fallen angels are everywhere. They lurk at crossroads, crouch behind doors, hide in trees, slip into beds, wait in caves, hover at weddings and childbirths, disguise themselves as friends, relatives-even disguise themselves as you. They are powerful; they are protean; they are enchanting. And, to the uninformed, they are often invisible.