Cinderella
The entire novel is a symbolic reconstruction of the Cinderella fairy tale with a modern world twist. Mia is obviously not in the dire circumstances of the heroine in the traditional fairy tale sense, but she is very much symbolically situated as the girl least likely to become a Princess. (Not really, of course, but within her world.)
Grandmere
Why isn’t his character referred to simply as Grandmother? Because she is not just a grandmother, but a fairy godmother. It is Grandmere who is the symbolic incarnation of the magically powerful fairy capable of turning a gangly, frizzy-haired klutz into an elegant princess.
Mia
When you are a kid, how do you really know who you are? You place all your trust in your parents or guardians or whoever is taking care of you. If they say you are so-and-so born in here-or-there then that is who you are. The future Princess of Genovia has always been the future Princess of Genovia, but she has never known herself as anything other the awkward girl from Manhattan. Her name thus becomes a symbol of the nature of identity. The story becomes one in which the diarist is forced to ask who is Mia, really? A question which translates, with appropriate awkwardness, into “who is me?”
Doc Martens/Blue Silk Heels
Thanks in no small part to the title character of the 1990’s pop culture touchstone Daria, laced Doc Martens combat boots became a popular symbol of third-wave feminist rebellion. It is appropriate, therefore, that these boots are worn by Mia as a key symbol of the novel’s intent to subvert princess tropes. Just as the blue silk heels she trades in the Doc Martens for once she accepts the role of princess is a symbol of how subversion is not necessarily a full-scale rejection of the princess concept.
Emasculation
Mia’s father has cancer and resulting from that condition he becomes infertile. It this sudden change in circumstances which stimulates the plot as he finally decides to Mia of her royal lineage. The reason for this, of course, is that since he cannot have any more children, he cannot produce a son who would have ascended to the role of rightful heir. A rather graphic passage has Mia writing in her diary that the treatment for the cancer involved the surgical removal of a testicle. This is both literally and metaphorically an emasculation under any circumstances, but considering that her father is the Prince of Genovia and the surgery directly contributes to Mia becoming the rightful heir, in this case it becomes a symbolic emasculation of archaic patriarchic aristocratic misogynist devaluation of women.