Who is Dr. Fileno from Eleven Short Stories = Undici Novelle and what is their importance?

Dr. Fileno is a fugitive character from another novel that intrudes upon the imagination of the writer in "A Character's Tragedy." Dr. Fileno has developed a philosophy of life that copes with hardships by distancing himself from events. He appeals to the writer to give him a story to appear in, but is dismissed by the writer.