What are three events and charactaers that contribute to Montag's change?

Two other important events and characters that influence Montag to change in Bradbury's Fahrenheit 451are Montag's first meeting with Faber, which the reader is told occurred before the opening of the novel, and Montag's encounter with the mechanical hound.

Faber leaves enough of an impression on Montag that Montag remembers him, and when Montag wants to learn to comprehend what he reads he knows to call Faber.

The mechanical hound spooks Montag, and demonstrates that the society is just not right.  It's threatening actions toward Montag place Montag as an outsider, even at the fire station.  The hound is just one more eerie aspect of the society for Montag to rebel against.