Alexandra shows us a side of compassion and understanding for the first time in chapter 24. When in the kitchen, she shows compassion for her overworked and under-appreciated brother.
"They're perfectly willing to let him do what they're too afraid to do themselves--it might lose 'em a nickel. They're perfectly willing to let him wreck his health doing what they're afraid to do."
She doesn't always agree with what Atticus says and does, but she does worry about him.
Then Alexandra shows true class to Scout when they have to go back into the room with the ladies. She, Maudie and Scout enter after the bad news, and Scout watches Alexandra and she saw "her head go up as she went through the door." Alexandra could have spread the gossip to this circle of ladies, but instead "looked across the room at [Scout] and smiled" inviting Scout to offer cookies to Mrs. Merriweather.
Scout sees her as a true lady because of her demeanor after hearing such horrible news. Scout says, "After all, if Aunty could be a lady at a time like this, so could I."
Aunt Alexandra demonstrates her familial loyalty in Chapter 24 of To Kill a Mockingbird.
At the Missionary Tea, the sanctimonious hypocrite Mrs. Merriweather disparages the black community for their disquiet after the trial and Atticus for having been Tom Robinson's defense attorney:
"...there are some good but misguided people in this town....Now, far be it from me to say who, but some of 'em in this town thought they were doing the right thing a while back, but all they did was stir 'em up...."
Alexandra becomes very upset at Mrs. Merriweather's innuendos but is prevented from saying anything to her by the return of Atticus. She hears her brother inform Cal that Tom has been shot dead, and he asks her to accompany him to Helen Robinson's. After he departs, Aunt Alexandra is extremely distraught. She turns to Miss Maudie:
"It tears him to pieces....What else do they want from him, Maudie?...They're perfectly willing to let him do what they're too afraid to do themselves—it might lose'em a nickel."
From her words, it is apparent that Alexandra really does love her brother, despite some of her earlier remarks. Scout is very impressed, and she decides that Aunt Alexandra is truly a lady and very loyal to her family.