Based on Guy Montag's struggles in Fahrenheit 451 about the hound, reckless drivers, and physical pain, what can a reader deduce about his character?
One of the prevailing themes in Fahrenheit 451 is the problem of ambivalence. The "theme" link below calls it "apathy and passivity," but it is essentially the same general concept. Apathy refers to a loss of interest, while ambivalence indicates a paralyzing inability to synch emotions and actions. In either case, progress halts.
Montag demonstrates ambivalence in his awe and fear of the hound and his love/hate relationship with his boss, his wife, and the books he stole. Montag's near catastrophic encounter with the speeding car resulted from his indecision, but ultimately ended his ambivalence so that he could take action. (It took a little longer to determine WHAT action.)
Montag is a tormented character. If he had let ambivalence rule his mind, he would have plummeted into passivity along with Mildred and most of the rest of society. People like Faber and Clarisse kept Montag off-balance enough that he kept thinking about the meaning of life and the purpose of literature. The mechanical hound sensed this philosophical bent and stayed on the alert. It was while Montag was deep in thought that he was nearly hit by a speeding car, and it was physical pain that prompted his to pursue his personal philosophy with more passion.This set him apart from all that he knew, but made him a natural fit with the "book-people" that he would eventually join.