The theme of reality vs. fantasy is one that the play centres around. Blanche dwells in illusion; fantasy is her primary means of self-defence, both against outside threats and against her own demons. Throughout the play, Blanche's dependence on illusion is contrasted with Stanley's steadfast realism, and in the end it is Stanley and his worldview that win. To survive, Stella must also resort to a kind of illusion, forcing herself to believe that Blanche's accusations against Stanley are false so that she can continue living with her husband.
One of the main ways Williams dramatises fantasy’s inability to overcome reality is through an exploration of the boundary between exterior and interior. The set includes the two-room Kowalski apartment and the surrounding street. Williams’ use of a flexible set that allows the street to be seen at the same time as the interior of the home expresses the idea that the home is not a place of safety. The characters leave and enter the apartment throughout the play, often bringing with them the problems they encounter outside. For example, Blanche refuses to leave her prejudices against the working class behind her at the door. The most notable instance of this effect occurs just before Stanley rapes Blanche, when the back wall of the apartment becomes transparent to show the struggles occurring on the street, foreshadowing the violation that is about to take place in the Kowalski’s’ home.
Blanche is the most fascinating character in A Streetcar Named Desire. One reason for this is that she has an absolutely brilliant way of making reality seem like fantasy, and making fantasy seem like reality. This element of Blanche's personality is what makes her character interest the audience and contribute to the excellence of the work. Returning to the beginning of the play, Blanche, shocked with the dirtiness and gloominess of Stella and