She is portrayed as a woman afraid of aging and light. She is always shown trying to hide from any type of thing which is likely to give a clue about what is her real age. The reader is already aware of this earlier in the play.
Williams uses this passage to illustrate that she likes darkness. For Blanche, light is to be feared while darkness is a kind friend on which she can rely to hide her fading beauty and, metaphorically, the ugliness and cruelty of the real world. A world in which she has had many bad experiences that no longer wants to remember. We can see an example of Blanche’s panic towards light when she says “(fearfully) Light? Which light? What for?”
As Mitch shows a clear an interest in Blanche, she is afraid he will find out about the chapter in her life when she is acting almost as a prostitute. Stanley finds out about this and threatens to tell. Another incident the audience is already aware of is when Blanche's husband committed suicide, a heartbreak for which she felt responsible and guilty. This passage partly explains Blanche’s character by exposing her reaction to these events, she has had a hard time accepting them and tries to replace truth with utopia. It is easy for an audience to understand why Blanche wants "magic" instead of "realism" after having witnessed this information about her fragile persona during the play. It is the only way to maintain her illusions, and if her illusions disappear, her sanity vanishes.
Even though Blanche may be a dreamy character, with dreamy thoughts, and hard to know when she is telling the truth or just making up a lie, she is really aware of being this way. She is shown here to be clear-headed and frank about her need to camouflage reality, to disguise the truth. “I misrepresent things to them. I don’t tell the truth, I tell what ought to be the truth.”
Finally, when she is conscious about having lost Mitch she adds “And if that is sinful, then let me be damned for it!” This also tells us that Blanche can have a wiser half, but can also have a bad temper if she gets excessively irritated about something she cares, as we can see some pages later, before the end of Scene 9, when Mitch has to run away in a startled grasp.
It could be said that Blanche is represented as a character dependant on male admiration and desire in order for her to have some self-esteem and this is reinforced in this passage when she says “There is some obscure meaning in this but I fail to catch it” and “What are you leading up to?”, as she wants to try to evade the conversation to make Mitch preserve the image of a good-looking lady he has about Blanche, even though she surely knows that Mitch is wishing to have a closer look at her.
In conclusion, this passage of the play reinforces the idea of Blanche not just being a character with lunatic dreams. She is proved here to be intelligent and self-aware of creating an imaginary disguised world in which she can retreat and hide from the ugliness of reality. We discover a more mature version of Blanche. Her foolish way of acting is cleared away to illustrate her true feelings, which are profounder than what the reader could have imagined at the beginning of the play.
