Spirits of the Lost

Spirits that still have souls have various spirit components. Their travel to different planes depends on their nature and what spirit components they let go. Many of these aspects go to the appropriate planes. Lost Spirits usually get absorbed in a near underworld, overworld, or both. Most people don't get to see that far. Seldom may you have souls that have spirit bound to people as ancestors. Accidents, traumas, or the end of bloodlines, can make a mess of things. They, too, have affinities for planes that you can feel and connect to.
How can dealing with earthbound spirits or lost souls open the door to dark entities - Demons? Demons pretend to be lost human souls, but the truth is that when a person dies, they do NOT roam the earth after death. There is not a place where people's souls are caught in the middle, or choose to roam the world, or that they are trying to finish something before they "pass over."
Demons "seem" friendly, trustworthy, even consoling and funny. All of the "nice" things they do are only ways of deceiving you to win your trust. Once they gain your faith, you have given them power into your life and enable them to advance their plan, totally take you over, and destroy you.