The indeterminacy of reality in both Pygmalion and A Streetcar Named Desire creates dilemmas of identity in both Eliza Doolittle and Blanche DuBois. Whereas Blanche's deceit is self-inflicted as she feigns a feminine ingenuousness and delight in order to maintain social acceptability, Eliza has her illusionary veneer of being a lady imposed upon her as an experiment by Dr. Higgins; thus the deceptive recreation of self is much deeper and damaging in Blanche than in Eliza.
In order to shield others from her unseemly past, Blanche makes elaborate efforts to create the facade of the socially elite Southern Belle surrounded by adoring men as she speaks incessantly of her former beaus. She reiterates that she has "always depended upon the kindness of strangers" as an attribute of her delicacy; however, Stanley, who has a distaste for pretense, suspects her deception. Certainly, her flirtation with him enables Stanley to see beyond her veneer of self-possession. Her fabricated illusions lead Stanley to unmask her past, which, in turn, causes Blanche's destruction as she can only hang on as long as she can deceive both others and herself. For, once her delusional world collapses as Mitch learns of her past and Stanley exposes her, Blanche comes apart, withdrawing completely from reality, and she can do no more than depend upon the kindness of the stranger who takes her to the sanitarium.
For Eliza Doolittle, the illusion of social respectability is also a means her maintaining a position as Dr. Higgins recreates her through the deception of speech, mannerisms, and dress. Whuke these veneers of upper class Victorian society establish the legitimacy of his experiment, they do not truly make Eliza a lady. And, despite what Shaw writes in his preface that gentility is simply a matter of education and environment, Eliza experiences a crisis of identity in Act IV as she no longer belongs in the lower class nor does she fit into the upper class:
"What am I fit for? What have you left me fit for: Where am I to go? What am I to do? What's to become of me?"
For, just as with Blanche of A Streetcar Named Desire, Eliza of Pygmalion is unable to change her real personality since no deceit can control the human heart. Nevertheless, because she has not deceived herself as has Blanche, Eliza is able to gain resolve and march out of the Higgins house in order to find what she now is, having learned from Higgins's behavior toward her
an even deeper truth, that social graces and class are not the true measure of a person's worth.
Certainly, in both plays deceit plays a critical role in underscoring the theme of identity.