In To Kill a Mockingbird by Harper Lee, why is Scout and Atticus's relationship important?

Since Scout is the narrator of the book, her relationship with her father is important.  Most of the book’s events relate to the trial of Tom Robinson. Scout’s relationship with her father is good.  Atticus is a conscientious father who tries to guide Scout through the difficult events.

When Scout gets frustrated because her teacher doesn’t like that she knows how to read, Atticus reacts compassionately.  He explains to her that she still has to go to school, but they will continue to read together.  He also tells her that she will get along better with people if she learns to look at things from their point of view.

Atticus is aware that the trial will be hard on Scout in particular, because she is just old enough to begin to understand what is going on but not really old enough to appreciate it completely.  He knows he can’t protect them from what people will say, so he tries to explain his reasons for taking the case.

“If you shouldn’t be defendin‘ him, then why are you doin’ it?”

“For a number of reasons,” said Atticus. “The main one is, if I didn’t I couldn’t hold up my head in town, I couldn’t represent this county in the legislature, I couldn’t even tell you or Jem not to do something again.” (Ch. 9)

Atticus wants his children to understand that you should do what you believe, no matter how difficult it is.  If something is hard or even impossible, that doesn’t mean you should not try if trying is the right thing to do.  This is also why he wants them to understand Mrs. Dubose’s addiction.  She struggles, and eventually succeeds.  Atticus wants Scout and Jem to understand that courage takes many forms.

Atticus is often busy, and his children find him satisfactory but boring.  While he threatens to spank them all of the time, he never actually does.  When Uncle Jack spanks Scout for fighting with her cousin Francis, Atticus says she deserved it, but he has gotten away with threats thus far.  Scout and Jem respect their father, and usually try to do what he tells them.

Scout and Jem worry about their father, and involve themselves in the case more and more.  When Atticus brings a lamp with him and goes down to sit outside the courthouse at night, the children follow him.  They witness him talk down an angry mob out to lynch his client.  Scout decides to help her father, and strikes up a conversation with one of the men, her friend Walter Cunningham’s father.

Scout worries about her father when Bob Ewell threatens him.  He tries to explain that Ewell is not dangerous, but of course he turned out to be wrong.  Scout’s reaction to Boo Radley when he saves her shows that she has learned Atticus’s lessons about treating people with respect.