Dialogue in Fielding's Tom Jones takes a second place to the narrator who, is a sense, is the main character since the narrator makes himself personable through an actual introduction and comments without cessation on events as they unfold. One example of the role of dialogue is in Chapter xii.
In this chapter, the role of dialogue is to present a moral lesson as Allworthy reprimands his companions for their uncharitable thoughts and words regarding the "shocking affair" of the captain's marriage to his new wife.
"Could I," said he, "sir, have suspected that a lady of such prudence, such judgment, such learning, should indulge so indiscreet a passion! or could I have imagined that my brother—why do I call him so? he is no longer a brother of mine——"
"Indeed but he is," said Allworthy, "and a brother of mine too."