Helen, the ghost had been helping the narrator write ghost stories. She was assigned this job by the main office of The Writer's Inspiration Bureau to help him. She was going on strike because of Ouija board fanatics. They kept them busy with their questions. She laid a condition that he was to exert his influence to make his friends and acquaintances stop using the Ouija board. Only then she would start helping him. 
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Helen,being a ghost can help the narrator in a better way as the narrator is writing ghost stories.
she was going on strike as everyone keep calling her to help them and this makes her fed up by their attitude.
She asked the narrator to ask everyone to stop using Ouija Board.if he stops she will help him.
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