Scout sees that her father has finally decided to stand up to his sister, Alexandra, though
It was a quiet digging in, never outright irritation.
Alexandra has attempted to gain control over the Finch household ever since she has arrived from Finch's Landing--to wear the proverbial pants in the family while Atticus is busy preparing for the trial. Slowly but surely, Atticus has taken a stand against his domineering sister: He has refused to fire Calpurnia; he has defended his children on their nighttime venture to the jail, where they have saved Tom--and Atticus--from the lynch mob; he has defended his talking about B. B. Underwood's hatred of Negroes in front of Calpurnia; and Atticus allows Scout to drink coffee, despite "Aunty's warning frown."