In The Help, how did the relationship between Celia and Minny change?

From the beginning of their relationship, Minny senses that Celia is different from other white women she has known. Minny says, "Miss Celia, the way she stares at me with those big eyes like I'm the best thing since hairspray in the can, I almost rather she'd order me around like she's supposed to" (page 49). Unlike other white women, Celia isn't used to having African-American maids help her, and she is truly grateful for Minny's help.

As time goes on, Celia and Minny become more like friends than like an employer and maid. When Celia has a miscarriage, Minny is there to help her, and Celia asks her, "What should we do about it?" (page 233). Though Minny does not like being pulled into Celia's problems this way, she becomes complicit in hiding the fact of Celia's miscarriage and resulting blood loss from Celia's husband, Mister Johnny. Celia and Minny's relationship changes because they share the secret of Celia's miscarriages--a secret that not even Celia's husband knows at this point of the novel. 

By the end of the novel, Celia and Minny are friends. Minny knows that Celia will never fire her, even if another white woman like Hilly asks her to do so. Minny knows that she can trust Celia and that Celia feels more indebted to her than she does to the other white women in the community, who have only treated Celia and Minny with contempt.