Mayella Ewell is a significant character in Harper Lee's To Kill a Mockingbird because she, in fact, is the catalyst for most of the action of the second half of the novel. In addition, she represents most of the attitudes of those who have Maycomb's "usual disease." Mayella is definitely a Ewell. She lives in a sordid environment that is characterized by filth and garbage. However, she brings one spot of beauty to the hovel where the Ewell family lives: along a crumbling wall are six, chipped slop jars from which bloom bright red geraniums. This detail suggests that there is something of value in Mayella, something that if it were nurtured could help her develop as a decent person unlike her father who is a degenerate man. He is cruel and sexually perverse and shiftless, refusing to work or parent his children. All the work in the household is left to Mayella while he sometimes kills some animals for food. With no parental guidance--abuse is all she receives from her father--Mayella must raise herself and care for her younger siblings, as well. It is no wonder that she does not know how to react to the politeness of Atticus Finch in the classroom, nor does she understand all that goes on in the courtroom. When she first comes to the stand, she talks behind her hands and cries before Judge Taylor. When the judge tries to reassure her that she has nothing to fear, Mayella says that she does not want Atticus to "do me like he done Papa, tryin' to make him out left-handed...." In response, Judge Taylor tells Mayella to sit up straight and tell the court what happened. Because she acts so childishly, Scout whispers to Jem, "Has she got good sense?" Her brother replies that Mayella has enough sense to get the judge to feel sorry for her, but she might just be acting.
Thus, it seems that Mayella has some of the deviousness of her father; she should still know not to repay Tom Robinson's kindness with the contempt that she displays in the courtroom. Certainly, her accusing lies and behavior which cost Tom his life are as reprehensible as any act, including his attack upon the children, that her father commits.