Aunt Alexandra orders Cal to take her bag and orders Scout to stop scratching her head, and these orders are typical for her.

The first two things Alexandra says are orders, and they are very characteristic of her because she is a take-charge kind of person and she expects to be listened to.  When Scout and Jem return home, they find Alexandra on the porch.  She immediately begins ordering people around.

"Put my bag in the front bedroom, Calpurnia," was the first thing Aunt Alexandra said. "Jean Louise, stop scratching your head," was the second thing she said. (Ch. 13)

Notice that Alexandra does not greet anyone.  She does not explain why she is there.  She does not hug or kiss her niece and nephew or give a polite greeting to Calpurnia.  She just orders Cal to get her bag as if she lives there and gives her orders every day, and then orders Scout to stop scratching her head as if she were her mother.

These orders are very much in character for Aunt Alexandra.  Alexandra is Atticus’s sister and Scout and Jem’s aunt.  She comes to visit and stay with the family to support Atticus during the trial.  Scout compares her to Mount Everest throughout her early life, saying “she was cold and there” (Ch. 9), though she wants Scout to wear dresses and act like a girl.

It does not seem to occur to Alexandra that this is not her house and her niece and nephew are not expecting her, let alone Calpurnia.  She likely considers Calpurnia “the help” and does not think her feelings require notice.  In fact, she attempts to get Cal dismissed, telling Atticus that she is no longer needed since Alexandra is there to take over the mothering duties. 

Alexandra is not the compassionate type.  While she is at the Finch household to uphold the family name while Atticus drags it through the mud by defending a Negro, she shows no affection or consideration for her brother or his children at first.  As the trial drags on, she sees how it affects them and begins to see them as people and even feels sorry for Atticus.  However, at this time she still considers him negligent in his duties of standing up for the family name and raising his children to live up to it.  By coming to the household, she hopes to remind the people of Maycomb who the Finches are in the community despite Atticus’s actions.