Who is Cpl. Fuller's mother from Welcome to the Monkey House and what is their importance?

Fuller is home after eighteen months in Korea, where he never actually fought. He is carrying frustration with him, which he directs at Susanna and at women in general. When he turns around in his barstool, he doesn't intend to make a speech or attract any attention. He hopes one or two people will notice his anger, but no more. It is only when the stool screeches and he realizes that he is the center of attention that he decides to attack Susanna. It seems as if he is almost just trying to save face, not to look ridiculous.