She represents wishful thinking and the inability to let go of the past.
Tennessee Williams. He is anyone who has ever wanted to move away from his family, and knew that he could do it, but was somehow obligated to stay for the benefit of people he didn't feel he should be responsible for.
He is also a dreamer and a poet. While his mother stays at home and believes in her delusions of grandeur that she is in charge and must take care of her family, Tom is the one who actually works and makes money.
Williams felt guilty that he had not been able to stop the procedure and help his sister. Tom sees his current situation and his family life as a coffin. When he talked to Laura after they had dinner, he tried to make her more comfortable because he felt that Laura was very shy.
It seems as if she is starting to escape her world of illusions.
In the play, Laura represents the very fragile, shy and emotionally crippled girl.