The trouble with writing about the afterlife is that thing about it being the undiscovered country from whose bourne no traveller returns -- how do you write about something that nobody's ever seen and that might not be comprehensible to a living person? Sometimes the near, familiar, part of the afterlife overlaps the living world, so that the deceased can walk around seeing how life goes on without them. (See Near-Death Clairvoyance.) Whether they can interact with the living depends on the story. See also Offscreen Afterlife, in which the afterlife is not depicted at all.