Who is Amanda Doyle from A Step from Heaven and what is their importance?

Amanda Doyle is Young Ju's best and only friend. She gives Young Ju a lifesaver in second grade after Young Ju tells her class that her brother has died. Apa believes Amanda is a bad influence on Young Ju. He does not want Young Ju to be like American girls who disobey and chase boys. Amanda is the reason Young Ju is forgetting that she is a Korean girl, and Apa forbids Young Ju to see Amanda. Young Ju obeys at first, but she has no other friends. Slowly she begins to spend more time with Amanda. When Apa discovers Young Ju's lies, he beats her in a drunken fury. He then beats Uhmma for defending Young Ju, and Young Ju calls the police. Apa is arrested, and the family never sees him again.