Tools of Characterization
Bradbury swears it was unintentional, but "Montag" is the name of a paper manufacturing company and "Faber" makes pencils. Cute. Also, it speaks to the fact that both men need each other, need to work together, to achieve a better end. Right?
Montag is challenged by his occupation as a fireman, but the Captain is defined by it. Beatty is the ultimate fireman, not only in practice but in ideology as well. Continuing in this trend, Faber is an ex-professor, and Mildred appears to do…nothing.
Speech and Dialogue
Both Beatty and Faber have great big monologues in the text (forming a foil, by the way, if you’re interested in that see "Character Roles"). We don’t get a full picture of Beatty’s character until we hear him rant about the danger of literature and the "happiness duo" he and Montag comprise. Likewise, we don’t know much about Faber until he explains his slant on literature.