Question

how had the writer become a cause of agony for the ghost

Answer 1

The ghosts helped unsuccessful writers by placing ideas in their minds on their own free will.But now the Ouija Board fanatics didn't allow them any fun and we're forced to work all day long .So the ghosts decided to go on a strike to protest against this Ouija board but then the writers wife got an Ouija board and called the same ghost which talked to the writer.The ghost then called the writer traitor.In this way the writer became a cause of agony for the ghost.