The Story of My Life by Helen Keller is an autobiography which indicates that the characters themselves obviously already exist. The characterisation shows the development of those characters, their personality traits and importance in the story as well as providing the reader with an easily recognizable idea of each character.
Helen uses direct characterisation in her descriptions of her "loving and indulgent father" and her mother's "loving wisdom." Indirect characterization also features as Helen uses it to describe the effect that most of the people in her life have on her and others and also her feelings towards them.
Ann Sullivan remains the one who "set my spirit free" (Ch 1) which tells the reader an enormous amount about Ann and Helen. It reveals the close relationship they had which lasted until Ann's death and, through various accounts of Helen's activities, the reader is introduced to a patient, humble and self-sacrificing person who helped Helen communicate her message. Helen's description of her visit to Dr Alexander Graham Bell also reveals his character. He is the one who provides the "door through which I should pass from darkness into light."(Ch 3). When describing her parents,Helen is loving and complimentary and acutely aware of the pain and confusion she causes when her tantrums are frequent, "almost hourly."
The descriptions provided by Helen are so vivid as to provide the reader with an immediate affinity with her and those instrumental in her development.