Character Analysis
Fanny is Mr. Hatter's second wife. She is stepmother to Sophie and Lettie, and she gives birth to Martha. When Mr. Hatter dies suddenly, leaving the shop in debt, Fanny does her best to place her three daughters in apprenticeships that will set them up for life.
Sophie is the eldest (and the shyest) so Fanny takes her on as an apprentice at the family hat shop. Lettie is beautiful and will make a good marriage, so Fanny places her at Cesari's pastry shop where she can meet a nice (and hopefully rich) guy. As the youngest, Martha is set for success, so Fanny sends her to learn witchcraft with her old friend Annabel Fairfax.
Initially, Sophie approves of Fanny's plans for the family:
Lettie, as the second daughter, was never likely to come to much, so Fanny had put her where she might meet a handsome young apprentice and live happily ever after. Martha, who was bound to strike out and make her fortune, would have witchcraft and rich friends to help her […] Sophie could hardly say that she simply felt resigned to the hat trade. She thanked Fanny gratefully. (1.19-20)
As we all know from Sophie's behavior throughout the book, she's a big believer in duty. She also has a lot of faith in fairytale clichés. So when Fanny puts Martha where she'll find the most success and then chooses more humble work for Sophie and Lettie, well, that's as it should be.
Of course, when Sophie finds out that Martha and Lettie have secretly switched places to pursue their dreams, her attitude toward her work and Fanny in general suddenly changes. Sophie realizes that she finds working at the hat shop deeply boring, but Fanny leaves her to take control more and more as she goes on endless "buying" (2.25) errands. Sophie starts to feel like Fanny is exploiting her, and it's partly her frustration over this state of affairs that drives her out of Market Chipping once the Witch of the Waste changes her into an old woman.
It's only when Sophie grows up a little bit—both emotionally and physically, thanks to the curse—that she sees things from Fanny's point of view, with a little less knee-jerk anger. When Sophie realizes how much Fanny (now called Mrs. Sacheverell Smith since she has remarried since Sophie's curse) has genuinely worried over her and missed her, she thinks:
[Fanny] was a lady who was still young and pretty, and she had found the hat shop as boring as Sophie did. But she had stuck with it and done her best, both with the shop and with the three girls—until Mr. Hatter died. Then she had suddenly been afraid she was just like Sophie: old, with no reason, and nothing to show for it. (20.41)
Sophie's changing responses to Fanny teach her an important lesson about not being too quick to judge. She lets her own feelings—and Martha's—get the better of her knowledge of Fanny, and she regrets this hastiness later. Now she can see that Fanny has always meant well and done her best, even if she got a bit careless with Sophie's feelings here and there.