Because Capt. Beatty purposely enticed him to do so by taking away his "green bullet" earphone and threating to track down who was on the other line and then began to taunt Montag until Guy, in a split decision, turned the flamethrower against Capt. Beatty and then knocked out the two other firemen as the hound pounced onto him partially injecting morphine into his knee as Montag incinerates the mechanical hound
Beatty explained to Montag that he had no idea why the hound was being hostile when he obviously knew the hound was out to get Montag. Beatty also told Montag there would be no trouble if he turned the book he stole in and Montag believed the false claim.
Beatty may have let the first alarm ride in Fahrenheit 451 to test Montag's loyalty and commitment to their society's beliefs. By allowing things to escalate, Beatty could observe Montag's reactions and decide whether he needed to intervene or if Montag would self-correct his behavior. Additionally, Beatty may have been trying to provoke Montag into taking actions that would lead to his own downfall.
Captain Beatty did this to Montag in order to get Montag back into the spirit of being a fireman so that Montag would believe the things that he used to believe as a fireman like how books are not important and should be burned because it is fun to burn things. Beatty also forced Montag as a punishment for hiding books.
Captain Beatty told Montag that firemen had always been responsible for burning books, even before the current society was established. This lie was used to manipulate Montag into believing that their society had always been built on censorship and book burning.
Beatty told Montag that if he handed the book over then the whole incident would be looked over. Montag is made to burn his own house because he is turned in by Mildred for having more books at home.
Beatty took Faber's ear piece from Montag. Montag knew this would lead them right to his friend and burns Beatty along with the ear piece.
Montag was worried that Captain Beatty would discover his hidden collection of books and his rebellious thoughts against the society that burned books. Montag feared Beatty would find out about his growing disillusionment with the oppressive government and the desire to protect knowledge.
Montag, Beatty, and Granger can be seen as traditional heroes in "Fahrenheit 451" for their bravery, actions, and beliefs that challenge the oppressive society they live in. Montag embodies the hero's journey as he undergoes personal growth and transformation. Beatty's knowledge and intelligence make him a formidable adversary, while Granger represents hope for a better future with his wisdom and guidance.
Beatty pretty much knows everything. He was going to find out about Faber, he knew about Montag's books and all of that whole thing. If Beatty hadn't been murdered he would have arrested Montag, found Faber, and stopped the entire operation.
Montag is a round character, we witness his change innerward and outwardly, the fire captain comes across as a round characer. Flat character would be his wife and her friends and the firemen.
Montag didn't run away before killing Captain Beatty because he was conflicted and influenced by the society he lived in. He had doubts about his beliefs and wanted to confront Beatty to gain clarity and understanding. Additionally, Montag felt a sense of duty and obligation to face the consequences of his actions.
Montag was afraid that Captain Beatty would discover his hidden collection of books and his growing disillusionment with the society and government that they were living in. He feared that Beatty might suspect his rebellious thoughts and actions.