In To Kill a Mockingbird, how does Atticus act toward Alexandra when she is staying in the house with them?

Atticus treats his sister, Alexandra, with overall firmness.  When she says or does something that he disagrees with, he confronts her in a polite, yet stern, manner.  Scout, the narrator, can tell that he is sometimes slightly irritated with her.  Scout can see "a subtle change in [her] father" and that he speaks to her in a way that is like "quiet digging in, [but] never outright irritation."  One day Aunt Alexandra suggests that they dismiss Calpurnia.  Atticus disagrees and is firm in telling his sister so.  He makes it clear that Calpurnia is a necessary part of the Finch household.

Aunt Alexandra does have some influence over her brother, however.  She tells him that his children should behave with the kind of breeding that lives up to the Finch name.  She pressures him into talking to them about their behavior, which he does without enthusiasm.