Answer:
THEME: It is better to face your fears than to avoid them.
The author encourages readers to confront their fears rather than avoid them. Martin's fear was able to track him down because he had fled from it.
Evidence:
Martin, a thin 12-year-old (written out and with hyphens). He lives on the 17th floor, is teased at school, and is constantly picked last for teams. He dislikes elevators. Martin's father definitely dislikes him. Martin dreads being alone in an elevator. He also feels nervous in the elevator with others.
The 14th floor elevator introduces the overweight woman. She wears a green blazer and dirty shoes. She fills the elevator entirely. She looks at Martin.
Martin dislikes the overweight woman. And why she's in the building, he wonders. Martin can't decide between the stairs and the elevator. The elevator portrays the big woman, while the stairs reflect his father's frailty. The big woman takes the next train up to the 18th level. Martin is stumped. He fears what will happen if the elevator gets trapped. He wants to go but feels he can't because of her. Martin asks his father about the big woman. His father accuses him of fear.
When Martin sees the overweight woman on his level, he takes the stairs. He trips and falls. He must now take the elevator. Martin takes the elevator with his father to the ninth level. The overweight woman boards the elevator on the tenth level. She calls him out and pushes STOP.