At the beginning of the book, Johnny is a round character (fully developed and exhibits many traits) but is static (does not change). He does not become dynamic (changes or grows during the course of the work) until what happens and he is forced to change? His father beats him with a 2 X 4 and Johnny doesn't cry.

He kills Bob and takes charge of the situation.

He and Marcia hit it off at the drive-in movie theatre.

He robs the gas station and has to run from the cops.