"The Miracle Worker" is a play about Helen Keller and how her life changes when Annie Sullivan arrives.  

Viney is a servant in the Keller household.  She has two children, Martha and Percy.  Viney is a kind and considerate person.  She notices that Kate Keller is spending a lot of time focusing on Annie's upcoming arrival.  Viney suggesrs that she rest.  Viney is also aware of Helen.  She notices that Helen has been wandering around upstairs.  Helen is aware that someone is about to arrive.  Viney helps to care for Helen.

Percy and Martha are Viney's children.  They are described as being black.  Both children play with Helen, but sometimes the siblings bicker.  Percy is sometimes annoyed by Helen's unusual behavior.  Martha, on the other hand, is more caring toward Helen.  When Helen tries to bite her own fingers, Martha shows concern.

James Keller is Helen's older half-brother.  His mother was married to Captain Keller until she died.  He is described as being "an indolent young man" (Act I, Scene II).  James is often aloof toward Helen's behavior.  He can be irritable and even rude.  He tells his father that he should put young Helen into an insane asylum.

The Miracle Worker is the story of Annie Sullivan's remarkable progress in helping Helen Keller to communicate after being left blind and deaf after an illness as a baby. Viney is the Keller family's dedicated servant who manages to retain calm in all the chaos of having a blind and deaf child in her midst. Her children, Percy and Martha are Helen's friends. Helen is fascinated by the movement of their mouths and mimics them but cannot understand why she gets no result. She puts her hand into their mouths to try and understand and Percy bites her. Helen tries it on herself and, in fact, bites herself. She takes her frustration out on Martha and scares Martha with a pair of scissors. Helen's mother, Kate, who after the last few years of caring for Helen is "a woman steeled in grief"(Act I) intervenes and James, who is Helen's older, half-brother comments on Helen's outburst. James is the son of Helen's father Captain Keller and feels detached from his father and unable to please him. He can see the potential for disaster if there is ever an occasion when there is no-one to stop Helen from hurting people.