How does Blanche DuBois' past lead to her own tragic downfall?This question is in comparison to how Stanley leads her to her tragic downfall.
Blanche DuBois, Stella's sister, moves in with them and seems to be planning on becoming a permanent guest. She and Stanley immediately dislike each other because they are such different personality types. She tries to turn Stella against her husband, making Stella aware of Stanley's many faults, especially his bad manners and bad temper. When Stanley comes to feel threatened by Blanche, who is dangerous in a sweet, Southern-belle way, he does some investigating into her past and learns that she was fired from her job as a teacher because she has a sexual attraction to underage boys and was involved in affairs with some of them. Blanche can't get another teaching job. She would have a hard time finding any other kind of employment because of her age and her unsavory past. She can become a permanent guest and disrupt their lives, especially since Stella is having a baby. Stanley uses this information to try to turn Stella against her sister and help him force her out. Blanche eventually has a mental breakdown when she sees that she is in danger of being homeless and destitute.