The crisis of identity is at the core of Fahrenheit 451. As the main character learns from a series of mentors and teachers, he sees his own identity melding with that of his instructors. This is also a means of scapegoating – if your identity is not entirely your own, then you are not entirely responsible for your actions. The novel explores the question of how to define the self, and seems to answer: actions.
Montag assimilates first Clarisse’s and later Faber’s identity to avoid thinking for himself. It is not until he washes in the river that he assumes his own new identity.