For some readers of Williams' A Streetcar Named Desire, the sympathies one may feel for Blanche can change over the course of the play.
When first coming in contact with Blanche, some readers may feel as though she was dealt a horrible hand in life and that she does not deserve the climatic rape by Stanley. Other readers of the play may find that Blanche's behavior over the course of the play resulted in something she "had coming."
Typically, the reaction to the play and Blanche can depend upon one's gender. Unfortunately, some male readers of the play tend to believe the way that she threw herself at Stanley only foreshadowed the inevitable rape. Female readers of the play tend to look at Blanche as a broken woman who does not deserve what happens to her (regardless of her sexual forwardness).
Unfortunately for Blanche, she is stuck in an environment which breeds violence and masculine power. The opening scene where Stanley throws up the package of meat is reminiscent of a caveman. Also, the violence which surrounds the play seems to be made out to be accepted given the women, both Stella and Eunice, allow the abuse to continue (as readers can easily assume that both have been repeatedly abused before).
Outside of that, a reader must come to terms with their own feelings about the circle of abuse which exists in life. For some, they may feel as though Blanche was "asking for it." Others may feel as though no type of abuse is acceptable. The changing of sympathy for Blanche relies heavily upon how one views these very different ideas.