Mountain spirits, water spirits, goblins, brownies... The idea of some invisible entities living next to us has always been present in the human mind. Sometimes these entities are far from us and live without causing any trouble, but it also happens differently: such an entity inhabits a person and causes a lot of inconvenience, and sometimes even trouble. So who are they? Tenacious fairy-tale heroes or real creatures, just built differently from us? What does this neighborhood threaten us with? Can a person somehow influence them? An attempt to understand these issues has been made in this publication.