It can be said that the central theme in Avi's The Man Who Was Poe concerns our abilities and inabilities to cope with our fears. Throughout the story, there are times when both the central characters, Edmund and Edgar Allan Poe, face their fears poorly and face them successfully.
In his book, Avi accurately characterizes the historical Poe as a man deeply troubled by grief over the deaths of his mother and young wife. His grief leads Poe to become paranoid of his fears and to be an alcoholic. Based on Avi's characterization of Poe, death is one of his greatest fears, and he copes with his fear of death by obsessively writing about death, just like he ends his story about Edmund with the deaths of Edmund's mother and sister, though both he and Edmund know in real life Edmund's family members are still alive and can still be rescued. Poe's fear of death makes it difficult for him to live his life well since he knows that life inevitably leads to death. Poe would have been living life well if he had actively sought to rescue Edmund's Sis, as Edmund pointed out in the final chapter:
You're always talking about death. . . but it's living you're frightened of (Chapter 22).
Despite coping badly with his fear of death and fear of life leading to death, there are a few fears Poe handles well in the book. For example, at Mrs. Whitman's tea party, though Poe first visualizes those he feels are critical of his work as demons out to get him, the more he speaks confidently of the feelings he expresses in his work, the more he is able to shift his thoughts and see his critics as normal people.
Similarly, as a child, Edmund starts the story off feeling afraid of being alone and helpless. When his aunt and sister go missing, he is so desperate for help that he asks Poe when he meets him though he begins to doubt that Poe, calling himself Mr. Dupin, is truly sane and sober enough to be of assistance. Multiple times, Edmund questions whether he should really trust Mr. Dupin. While it is Mr. Dupin who unravels the mystery near the end of the novel, it is Edmund who figures out Mr. Rachett and Mr. Peterson took his sister on board the Sunrise and goes after her. It is also Edmund, not Mr. Dupin, who rescues Sis from drowning, which is a strong example of Edmund doing an excellent job of coping with his own fear of helplessness.