Why do you think Bradbury would introduce Clarisse before Montag’s wife, Mildred in Fahrenheit 451?
Bradbury introduces Clarisse first for several reasons. First, he wants to plant ideas that will take root in Montag's mind, eventually changing his passive nature to an action-directed one. Secondly, Clarisse has a mind: she is very much alive to the world around her and to ideas. She lifts Montag up, even while she shakes him up. She gets his brain working, and he starts thinking and wondering and asking questions. Mildred, Montag's wife, is almost dead. She is all but numb—not enough to pass on the chance to release herself from an unhappy existence by attempting suicide. There is no life or animation in Mildred: she is like a robot.
By meeting Clarisse first, we can imagine what Montag can do if he tries. In meeting Mildred second, we know what kind of life Montag will have if he remains where he is, without dreams, ideas or a desire to learn.
Clarisse is simply more important. If Montag hadn't met Clarisse first, Millie's overdose would probably not have had much of an impact on him. He would just think it was normal. But meeting Clarisse first gives him a sense that things can and should be different. So Clarisse has to come first for the story and she also should come first because she is more important to Montag's development as a person.
I think that Bradbury introduces Clarisse before Mildred because of the impact she has on Montag's way of thought and sense of being in the world. Even though she is his wife, Millie really has little bearing on causing change in Montag. She is representative of the Status Quo, the way things are. Yet, Clarisse is a voice, the first real and definitive voice that represents how things should be for Montag. She is the first voice to challenge him and compel him to think and reflect about how what he is doing needs to stop. From a characterization point of view, Clarisse represents the first instant where Montag sees challenge or an oppositional force exerted upon him. It is through Clarisse that Montag accomplishes a sense of change within him, something that marks his transformation throughout the narrative. Clarisse is the force that causes Montag to start testing the boundaries with his wife, examining the nature of their relationship, and even triggering the process of questioning this aspect of his life, as well. Through Clarisse, Montag is able to begin the transformation and change that defines his character, reason enough for Bradbury to introduce her first.
Bradbury introduces Clarisse before Mildred beacause she is so interesting to Montag. She makes him think and ask why. When you read Clarisse's and Montag's conversation, they are really communicating, and even though Montag doesn't quite think so yet, he really likes the way she thinks. Then Mildred is introduced and its her more talking at Montag than talking with Montag. She talks about the walls and her channels, where Clarisse talks about dandalions and the most simple things. When Clarisse is introduced you are impressed and intregued, when Mildred comes into the book your very unempressed. She has overdosed, possibly trying to commit suicide. Their is someone who love the small pleasures of life, then their is a depressed lady that can't admit that she has an issue.