In many ways Calpurnia is a mother-figure to Scout. Cal, as Scout refers to her, is also a teacher, nanny, housekeeper, and friend to everyone in the family.
Because Atticus is a widower, he relies on Calpurnia to take care of the children when he is gone, much like his wife would have done. She prepares their meals, punishes them when they are out of line, and imparts life lessons and advice. She is strict with both children, but she loves them and they love her.
They have a good relationship because it is based on love and trust. Scout has never known her life without Calpurnia. Scout shares her most intimate moments with her, for better or worse. As a result, you could say they have a strong friendship.
Calpurnia is the Finch's African-American cook and housekeeper who plays the role of mother to Scout and Jem. Scout views Calpurnia as strict, yet understanding throughout the novel To Kill a Mockingbird. Scout mentions their "epic one-sided battles," and says she has "felt her tyrannical presence as long as she could remember." (Lee 7) Calpurnia is always quick to discipline Scout for her misbehavior. For instance, when Scout questions Walter Cunningham's eating habits during a meal at the Finch residence, Calpurnia takes Scout into the kitchen to give her a lesson in manners. Cal says,
"Yo' folks might be better'n the Cunninghams but it don't count for nothin' the way you're disgracin' 'em---if you can't act fit to eat at the table you can just set here and eat in the ketchen!" (Lee 33)
Despite Calpurnia's authoritarian characteristics, she is also portrayed as a caring individual. When Scout comes home from a rough first day at school, Calpurnia makes Scout her favorite meal "crackling bread," and greets her with a kiss. Later on, when Jem begins excluding Scout from activities and growing distant, Calpurnia comforts Scout by saying,
"He's gonna want to be off to himself a lot now, doin' whatever boys do, so you just come right on in the kitchen when you feel lonesome. We'll find lots of things to do in here." (Lee 154)
In addition to being a caregiver, Scout views Calpurnia as a source of knowledge throughout the novel. Scout perfects her writing under Calpurnia's tutelage and experiences African-American culture firsthand after Calpurnia takes her to First Purchase African M. E. Church. Scout looks up to Calpurnia as a role model and their friendship manifests throughout the novel.