Throughout the story, the Miller shares a number of exaggerated, didactic thoughts on friendship. These hyperbolic reflections are marked by irony, since his grand ideas and reflections tend to clash directly with his own behavior. However, it is important to note that, because he never intentionally says the opposite of what he means, the Miller isn't using verbal irony. The irony of his words and deeds are lost on him, but it's apparent to the Linnet and to the reader. By linking the Miller's characterization with situational irony and hyperbole, Wilde lays bare the obliviousness of those who justify their exploitation of vulnerable people with the conviction that they are morally or intellectually superior.
The Miller's words and actions are consistently contradictory. In a single sentence, the Linnet states both that the Miller never shares any of his great quantities of food or farm animals with Hans and that nothing makes Hans happier than listening "to all the wonderful things" the Miller says about "the unselfishness of true friendship." In the winter, the Miller and Hans don't see each other because the Miller won't make any material gains by seeing Hans. Since Hans subsists on the products of his garden, he "[suffers] a good deal from cold and hunger" and is "extremely lonely." This is a time when Hans could really use a friend's help, but the Miller claims he is avoiding Hans to prevent him from feeling envy. The hyperbole and irony of the Miller's words is striking, as he both admits to avoiding his friend in a time of need and claims to have his friend's best interests at heart: "I am his best friend, and I will always watch over him."
Another irony is that the Miller actually addresses the discrepancy between words and deeds at a certain point in the story. However, he doesn't view this discrepancy in the same way as the Linnet or the reader. The accepted view tends to be that words unaccompanied by action are empty. After all, as the well-established idiom proclaims, actions speak louder than words. Nevertheless, the Miller claims the exact opposite:
“Lots of people act well," answered the Miller; "but very few people talk well, which shows that talking is much the more difficult thing of the two, and much the finer thing also."
In the Miller's view, speech is worth more than behavior because he believes the former is rarer than the latter. Part of what makes this comment ironic is that the Miller evinces some degree of self-awareness through it. By stating that he values speaking well over acting well, it turns out that the Miller recognizes that his actions do not measure up to his words. However, while this is precisely what makes him a bad friend, he believes it actually makes him a good friend.
Throughout the story, the Miller's actions contradict his claims about caring for Hans. After repeating the idea that true friendship is "quite free from selfishness of any kind," the Miller uses the fact that he has offered Hans a broken wheelbarrow that he doesn't himself need as an excuse to make Hans carry out a long series of tasks for him. These tasks prevent Hans from doing his own work, thoroughly exhaust him, and even bring about his death. The Miller tells Hans at one point that "there is no work so delightful as the work one does for others," yet he never once lifts a finger for anyone but himself. In the end, Hans never receives the much-invoked wheelbarrow from his supposedly devoted friend—he only receives empty words.
The Linnet's comments about the Miller are marked by verbal irony throughout the story. He repeatedly refers to the character as a good and devoted friend, yet he only ever gives examples of the Miller behaving in a selfish, unkind manner. The Linnet's verbal irony ensures that he is able to hint at his thoughts on the events of the story without expressing them explicitly. Although the verbal irony gives an idea of where the Linnet's sympathies lie, he never inserts his personal commentary into the story he is telling.
For example, when the Linnet first introduces the Miller into the story, he claims that he is Hans's most devoted friend. However, the next piece of information he gives—seemingly to back up this claim—would only attest to the opposite: that the Miller does not treat Hans well at all.
Little Hans had a great many friends, but the most devoted friend of all was big Hugh the Miller. Indeed, so devoted was the Miller to little Hans, that he would never go by his garden without leaning over the wall and plucking a large nosegay, or a handful of sweet herbs, or filling his pockets with plums and cherries if it was the fruit season.
The first sentence of this passage sets the reader up to expect that the Linnet will describe the various ways in which the Miller acts as a devoted friend. When the Linnet immediately disproves his earlier claim in the following sentence, the reader understands that the bird is most likely narrating with a subtle kind of irony. He calls the Miller Hans's most devoted friend as a way of mimicking the Miller's own words about himself, all while revealing the ways in which he is everything but. After the reader has been given a stirring description of Hans's beautiful, abundant garden, the image of the Miller leaning over the wall and stealing flowers or filling his pockets with fruit feels like a particular encroachment on the honest little Hans.
Throughout the fable, the Linnet never directly articulates his own personal thoughts or value judgments on whether the Miller is behaving justly towards Hans. This lack of explicit input in the story highlights the Miller's insolence in a unique way, as the indirectness of the Linnet's verbal irony forces the reader to reach their own conclusions without the influence of already-elaborated value judgments. Verbal irony allows the Linnet to express his opinions while also ensuring that the narrative remains free from the storyteller's straightforward opinions.
Depending on how one approaches the story's title, it's possible to read it as containing a layer of verbal irony as well. It's unclear whether the "devoted friend" in question is Hans or the Miller. If the title is pointing to the Miller, it would be marked by irony, as the story only reveals him to be a selfish, evil-spirited person in his relationship with Hans. If the title is pointing to Hans, the title wouldn't be ironic, because Hans really is a devoted friend—so much so that his devotion has fatal consequences. In either case, the word "devoted" in the title contains connotations that are hidden from the reader at first glance. A word that tends to contain positive connotation, it comes to be stripped of this by the end of the Linnet's story. One of the characters is too devoted, the other character is not devoted enough.
