How has Calpurnia developed throughout Harper Lee's To Kill a Mockingbird?

In Harper Lee's To Kill a Mockingbird, though Scout's relationship with Calpurnia changes as Scout gets older, Calpurnia is actually a static character. A static character is one that does not struggle against any conflict and, therefore, does not change as a result of that conflict. Therefore, though Scout's relationship with Calpurnia does develop as the novel progresses, Calpurnia as a character does not develop. Regardless, we do learn more about her as Scout matures and learns more about Calpurnia herself.

At the beginning of the novel, Scout sees Calpurnia as nothing more than an antagonizer. Scout is frequently getting into trouble with Calpurnia, and Atticus is always taking Calpurnia's side. However, little does Scout realize that Calpurnia sees herself as Scout's mother-figure, and Calpurnia's mother qualities are revealed the more Scout matures.

We first see Calpurnia's mothering qualities when Scout comes home from her first day of school. Calpurnia is so proud of Scout growing up and missed  Scout's presence in the house so much that Calpurnia makes Scout's favorite for dinner, a "pan of cracklin' bread" (Ch. 3). Calpurnia even kisses Scout for the first time. Calpurnia further demonstrates her mothering qualities by protecting the children from the mad dog and even attempting to protect them from the sight of their father shooting the mad dog. In addition, Calpurnia protects the children from Lula's insults the day Calpurnia brings the Finch children to her all-black church as her guests while their father is away.

Later, in Chapter 12, when Jem starts growing up and acting differently, especially by spending less time with his sister and yelling at her for not acting like a girl, we see just how close Scout and Calpurnia have grown over the course of the novel. Calpurnia explains that "Mister Jem" will want to be off by himself a lot now and gives Scout the following invitation:

[Y]ou just come right on in the kitchen when you feel lonesome. We'll find lots of things to do in here. (Ch. 12)

At the beginning of the novel, Scout narrates that Calpurnia was always shooing Scout out of the kitchen. Therefore, Calpurnia's invitation not only shows Calpurnia's motherly attributes, but it also shows she thinks Scout has matured to the point that they can now peacefully spend time together.

Hence, as we can see, Calpurnia displays the same motherly qualities all throughout the novel; however, as Scout's relationship with Calpurnia develops, more of Calpurnia's motherly characteristics are revealed.