Montag has always been intimidated by Beatty. In fact, when he goes to Faber, he goes with two ideas in mind. He wants Faber to teach him about books, and he wants to be able to respond to Beatty. When Beatty uses logic with Montag, he quotes all these authors and books, things unfamiliar to Montag. He is so good at it that each time he quotes something, he finds an opposite example and confuses Montag totally. Montag tells Faber,
"God, how I want something to say to the Captain. He's read enough so he has all the answers, or seems to have. His voice is like butter. I'm afraid he'll talk me back the way I was. Only a week ago, pumping a kerosene hose, I thought: God, what fun!" (pg 89)
However,at the beginning of Book Three, when they show up at Montag's house to do the burning, Beatty taunts Montag. He finds the green bullet and threatens to find Faber.
"We'll trace this and drop in on your friend." (pg 118)
This infuriates Montag, and he releases the safety catch on his flame thrower.
"Thinking back later he could never decide whether the hands or Beatty's reaction to the hands gave him the final push toward murder." (pg 119)
Beatty taunts him again.
"Well, that's one way to get an audience. Hold a gun on a man and force him to listen to your speech. Speech away. What'll it be this time? Why don't you belch Shakespeare at me, you fumbling snob? .....Go ahead now, you second-hand litterateur, pull the trigger." (pg 119)
Montag did, and Beatty became a shrieking blaze.
"....no longer human or known, all writhing flame on the lawn as Montag shot one continuous pulse of liquid fire on him." (pg 119)
Beatty ran to his backyard, retrieved four of the books Mildred had missed, and ran for his life. Suddenly he fell to the ground because a realization came into his head.
"Beatty wanted to die.
In the middle of crying Montag knew it for the truth. Beatty had wated to die. He had just stood there, not really trying to save himself, just stood there, joking, needling, thought Montag, and the thought was enough to stifle his sobbing and let him pause for air. How strange to want to die so much that you let a man walk around armed and then instead of shutting up and staying alive, you go on yelling at people and making fun of them until you get them mad, and then....." (pg 122)
Montag realizes that Beatty wanted to die and provoked him into killing him.