In keeping with the straightforward style of the narration, "The Miller's Tale" relies heavily on direct characterization, or simply telling you what the characters are like. In Nicholas's portrait, for instance, we learn that he is "sleigh and ful privee" (93). With Absolon, the narrator tells us he is a "myrie childe" (217) and "somdeel squaymous / Of fartyng, and of speche daungerous" (229-230).
For the most part, these bits of information that we get in the characters' portraits are confirmed by their actions later on. There is one important exception, though: despite the fact that the narrator says of John "jalous he was, and heeld [Alisoun] narwe in cage" (116), John's actions over the course of the tale actually contradict this assessment. This lapse in judgment makes us question our narrator's reliability, and whether or not we should trust some of his other direct characterizations. At the very least, we should be cautious, always weighing our impressions of the characters' actions against what the narrator tells us about them directly.
With John, we hear little about his appearance or habits. The direct characterization we do get (that he is jealous) turns out to be inaccurate. So we must rely almost entirely upon John's actions to learn about his character. John often travels away from Oxford on business, leaving his young wife alone in the company of his young male boarder, suggesting that he is not actually jealous. When Nicholas holes up in his room all day and appears to be in a daze, John worries about him and goes to great trouble to try to revive him. When he hears of the flood, his sole concern is for Alisoun, whom he takes great pains to save from an imagined doom. Both of these actions suggest that John is a compassionate and caring individual. Finally, John falls for Nicholas's absurd story about the impending flood without any hesitation, suggesting that he is extremely trusting and perhaps not the sharpest tool in the shed.
In the case of the two students, Nicholas and Absolon, their habits tell us important information about their characters. Despite his having studied the liberal arts, most of Nicholas's attention is focused on fortune-telling, suggesting that he longs to distinguish himself by knowing more than other people do, and perhaps more than he should. Nicholas's engagement in illicit affairs tells us that he is fairly unethical, at least when it comes to respecting the marriage bond. Absolon not only excels in his clerkly duties but also runs a barbering business on the side. He is also skilled in various kinds of dance and music. It seems that Absolon likes to distinguish himself through exhibition. Indeed, when he courts Alisoun later on, it is by taking to the stage, both with song and in theater. Absolon is also in the habit of combing his hair meticulously, arranging his clothing perfectly, and chewing herbs to make his breath smell sweet. This obsession with personal grooming aligns with his squeamishness about farting, suggesting a person for whom cleanliness is paramount.
Physical appearance is most important to our understanding of Alisoun's character, but it is also an element in Absolon's characterization. Alisoun's portrait describes her clothing, complexion and body in great detail, relying heavily on metaphors of barnyard animals and plants. The effect of this description, as we mention in the "Characters" section, is to associate Alisoun with animal sexuality and to suggest that she is primarily an object of desire. In the case of Absolon, his golden locks, always meticulously parted down the center, and his carefully-donned outfit and red tights, give us the impression of a person who is extremely concerned with his appearance.