Montag changes from enjoying being a fireman to going on the run hiding books.
At the beginning of the story, Montag seems to really enjoy his job as a fireman. Firemen in Montag’s world don’t put out fires—they set them to burn books.
It was a special pleasure to see things eaten, to see things blackened and changed. (Part I)
When Montag meets Clarisse, he begins to look at life differently. She asks if he is happy, and he realizes he is not. He never thought to question his life or society before. Even after Clarisse mysteriously disappears, she leaves a mark on him. He begins to wonder.
One day during a fire, Montag steals one of the books. He takes it home and shows it to Mildred. He is unhappy with their life. They barely talk, and there is no affection or closeness between them. As a result, Montag looks for truth in books. Mildred thinks he is crazy and worries that he will get in trouble.
Montag gets depressed. It is not long before his secret book-loving is discovered, and firemen arrive to burn his house. Angry, he goes on the run and joins the secret society of book memorizers who are keeping the books safe until society self-destructs.