The novel's opening sentences, as Lockwood reflects on his first visit to Wuthering Heights and meeting Heathcliff, are packed with foreshadowing:
1801—I have just returned from a visit to my landlord—the solitary neighbour that I shall be troubled with. This is certainly a beautiful country! In all England, I do not believe that I could have fixed on a situation so completely removed from the stir of society. A perfect misanthropist’s Heaven—and Mr Heathcliff and I are such a suitable pair to divide the desolation between us. A capital fellow!
Some of the irony of this passage is due to the fact that, though Lockwood calls himself a "misanthropist," he's clearly exaggerating—he means something more like "introvert." If he truly hated the company of fellow humans, Lockwood wouldn't have sought out his landlord and neighbor, nor would he have cheerfully judged him "a capital fellow."
The greater irony, though, is the fact that, far from being "a capital fellow," Heathcliff is a misanthropist—though neither Lockwood nor readers know that yet. Despite initial appearances to the contrary, Heathcliff isn't a sociable neighbor with whom to "divide the desolation" of this remote country. In fact, Heathcliff has been a terror to his former neighbors at Thrushcross Grange, but Lockwood will only learn this as Nelly tells him the whole story over the course of the novel. The passage thus foreshadows that, indeed, the Grange and the Heights are incredibly remote from "civilized" society, and in this lonely setting, Heathcliff will be Lockwood's main source of entertainment—though not in the neighborly way he expects, but as the villain of a tale spanning decades.
When Lockwood has dinner at Wuthering Heights for the first time and meets the household, he keeps blundering as he tries to figure out everyone's relationships. He first assumes that Cathy (Linton's widow and Heathcliff's daughter-in-law) must be Heathcliff's wife and then, once corrected, falsely assumes that she's married to Hareton. This is an instance of situational irony because the relationships are not what he, or the reader, expect.
‘Mrs Heathcliff is my daughter-in-law,’ said Heathcliff, corroborating my surmise. He turned, as he spoke, a peculiar look in her direction, a look of hatred unless he has a most perverse set of facial muscles that will not, like those of other people, interpret the language of his soul.
‘Ah, certainly—I see now; you are the favoured possessor of the beneficent fairy,’ I remarked, turning to [Hareton].
Lockwood's blundering throws the reader right in with his own disorientation and confusion; though readers don't know who's who any better than he does, they now understand that this is going to be a complicated story. The "look of hatred" that Heathcliff throws at Cathy reveals generations' worth of pent-up rage, foreshadowing the strife and revenge to come when Nelly tells Lockwood the families' backstory.
The irony in this passage has its humorous side, as the reader pities Lockwood's inability to say anything right; his elevated gentleman's language ("the favoured possessor of the beneficent fairy") doesn't match the rural Yorkshire setting or the animosity-filled family atmosphere. Besides tasting the palpable awkwardness, readers are also primed to pay close attention to the narrative in order to untangle these relationships—and to understand how they grew so embittered.
The morning after Lockwood sleeps at Wuthering Heights, he hears Hareton Earnshaw stumble into the kitchen, swearing under his breath:
A more elastic footstep entered next, and now I opened my mouth for a ‘good morning,’ but closed it again, the salutation unachieved; for Hareton Earnshaw was performing his orisons, sotto voce, in a series of curses directed against every object he touched[.]
"Orisons" is a somewhat archaic term for "prayers," so when Lockwood refers to Hareton's ill-natured grumbling as "orisons," he's using verbal irony—Hareton is cursing, essentially doing the opposite of praying.
Lockwood's narration often uses mildly ironic and elevated diction, like "performing his orisons sotto voce," to indicate Lockwood's gentlemanly status and his more detached perspective. In addition, though, there's a marked tone shift between the previous night and this morning. Following Lockwood's nightmare-ridden stay at Wuthering Heights, he's no longer giving its residents the benefit of the doubt; he's feeling rattled by what he's experienced there and, accordingly, he starts using a more suspicious and sarcastic tone. By ironically attributing respectable, civilized piety to Hareton, he means to imply that Hareton is actually uncultured, rough, and impious, prompting readers to wonder what has made Hareton so apparently brutish.
Catherine is confiding in Nelly that she has accepted Edgar's marriage proposal, yet she's conflicted because she also loves Heathcliff—whom she could never marry:
It would degrade me to marry Heathcliff, now; so he shall never know how I love him; and that, not because he’s handsome, Nelly, but because he’s more myself than I am.
Nelly notices that Heathcliff is in the room, but he runs away when he overhears Catherine saying it would "degrade" her to marry him. Heathcliff's running away is an instance of dramatic irony because readers know, through Nelly's narration of Catherine's words, that Catherine passionately loves Heathcliff, but Heathcliff leaves before he hears Catherine's full declaration—she goes so far as to say that she and Heathcliff are effectively the same person, something she will never claim about Edgar.
The same passionate nature that fuels his love for Catherine leads Heathcliff to hastily abandon her and Wuthering Heights. Heathcliff's departure dooms whatever hope there could have been for a romantic relationship with Catherine, as she then follows through with marrying Edgar Linton instead. Moreover, it's ironic that a half-overheard, misunderstood sentiment leads to decades of misery for the families of Wuthering Heights and Thrushcross Grange. Furious about the way Hindley has degraded him in Catherine's eyes through mistreatment, Heathcliff later goes on to abuse Hindley's son Hareton, marry and mistreat Isabella Linton, and kidnap Catherine's daughter Cathy in revenge. Thus, Heathcliff's fleeing turns out to be the novel's turning point—though right now, what readers know is bad enough: that Heathcliff doesn't realize how much Catherine loves him and might never know.
When Isabella believes that she has fallen in love with Heathcliff, Catherine and Nelly try to warn Isabella about Heathcliff's true nature, but she doesn't heed them. Catherine uses nature imagery to convey that Isabella would be completely at Heathcliff's mercy.
"Tell her what Heathcliff is—an unreclaimed creature, without refinement—without cultivation; an arid wilderness of furze and whinstone. I'd as soon put that little canary into the park on a winter's day as recommend you to bestow your heart on him! [...] [H]e'd crush you, like a sparrow's egg, Isabella, if he found you a troublesome charge."
In particular, Catherine uses imagery associated with tame birds (a pet canary that couldn't fend for itself outdoors) or defenseless eggs (sparrow eggs are among the tiniest of wild birds' eggs) to warn Isabella that Heathcliff will treat her cruelly, and there will be nothing she can do to protect herself from him. In the same chapter, Nelly, too, advises Isabella to forget about Heathcliff: "He's a bird of bad omen; no mate for you." "Bird of bad omen" is an idiom that means Heathcliff is bad news, auguring a bad future for Isabella. In her more colloquial tone, Nelly builds on Catherine's more picturesque imagery to make clear that Heathcliff isn't the type of "bird" to match the delicate Isabella.
There's additional nature imagery in this passage: Catherine also associates Heathcliff with the wild, uncultivated Yorkshire moors. "Furze" refers to an evergreen shrub (gorse) that's ubiquitous on the moors; whinstone refers to dark, massive rocks common in the North of England. By contrast, Isabella has always been sheltered at Thrushcross Grange and carefully cultivated as a gentleman's daughter. She and Heathcliff are a complete mismatch, and unlike Catherine (whose choice of words suggests she's drawn to the wild moors, like Heathcliff), Isabella can't stand up to his rough, "unreclaimed" nature.
Dramatic irony is also at work in this passage, as readers know that Heathcliff is as bad as Catherine and Nelly say, but must watch Isabella naively blunder into a doomed marriage in the chapters ahead.
After Catherine dies, Isabella tells Nelly how Heathcliff has been behaving in his mad grief, ironically likening Heathcliff to a pious Christian:
There he has continued, praying like a methodist; only the deity he implored is senseless dust and ashes; and God, when addressed, was curiously confounded with his own black father! After concluding these precious orisons—and they lasted generally till he grew hoarse, and his voice was strangled in his throat—he would be off again; always straight down to the Grange!
Isabella recently married Heathcliff and has suffered from his abuse, telling Nelly earlier that she doesn't regard him as human. Here, she ironically twists the simile "praying like a methodist" around by alluding to Satan and suggesting that, far from being a prayerful, sympathetic mourner, Heathcliff is a monster and damned.
The Protestant religious movement known as Methodism had only become widespread in England by the mid-1700s; at this point in the story's timeline (the 1780s), "Methodist" was a broad-brush term that could be used to apply to anyone who was fervent in their religious practice, especially in enthusiastic prayer. But Isabella doesn't mean the term at all literally, as her next comments show.
The "deity" of "senseless dust and ashes" refers to the late Catherine. In other words, Heathcliff isn't even praying fervently to God, but to the spirit of his dead beloved. Further, "his own black father" refers to the devil, with whom Heathcliff, in his grief and rage, blasphemously conflates God (and Isabella calls Heathcliff the devil's offspring). The fact that Heathcliff's desperate "prayers" are a mashup of pleading and curses (none of which are directed to God) demonstrates that he is utterly irreligious. Like "methodist," then, "precious orisons" (or prayers) is verbal irony, sarcastically characterizing Heathcliff's blasphemous ravings as sincere piety.
Nelly describes how Heathcliff came to be the owner of Wuthering Heights after Hindley Earnshaw mortgaged it away to pay off the debts he accumulated by gambling with Heathcliff. This is an instance of situational irony, given everything readers would expect about the importance of inheritance in old, respected families like the Earnshaws.
The guest was now the master of Wuthering Heights [...] Earnshaw had mortgaged every yard of land he owned for cash to supply his mania for gaming: and he, Heathcliff, was the mortgagee. In that manner, Hareton, who should now be the first gentleman in the neighbourhood, was reduced to a state of complete dependence on his father’s inveterate enemy; and lives in his own house as a servant deprived of the advantage of wages, and quite unable to right himself, because of his friendlessness, and his ignorance that he has been wronged.
Recall that when readers are introduced to Wuthering Heights, Lockwood notices the name of family ancestor "Hareton Earnshaw" above the door. Later, Hindley's son Hareton is named after his 16th-century forebear—a plain indication that Wuthering Heights is meant to be passed down to future generations of Earnshaws. Given the significance of inheritance in this society, then, it's an especially grievous irony that the current Hareton Earnshaw has been swindled out of what's rightfully his by Heathcliff—his father's poor, adopted orphan brother with no natural claim on the Earnshaw heritage.
This circumstance is also meant to show how truly dissipated Hindley became: allowing his son's inheritance to be gambled away is a shameful dereliction of duty. And after Hindley dies, young Hareton has no idea what he's lost because Heathcliff raises him the way Hindley raised Heathcliff —that is, like a servant, isolated and uneducated. So, even though Heathcliff is the one who abuses and degrades Hareton, he does so in retaliation for the way Hindley treated him, making Hindley responsible for the Earnshaws' downfall twice over.
Cathy makes fun of Hareton for trying to teach himself to read. Readers know that Hareton has been struggling to learn to read—and choosing to recite Cathy's favorite passages—in order to impress her and win her affection, but Cathy ironically attributes his efforts to mockery.
'[...] he has no right to appropriate what is mine, and make it ridiculous to me with his vile mistakes and mis-pronunciations! Those books, both prose and verse, were consecrated to me by other associations, and I hate to have them debased and profaned in his mouth! Besides, of all, he has selected my favourite pieces that I love the most to repeat, as if out of deliberate malice!’
This instance of dramatic irony highlights how unkind Cathy can be, especially in the miserable environment of Wuthering Heights, and it stirs readers' sympathy for Hareton. Stuck there against her will, Cathy assumes that Hareton's fumbling attempts at kindness could only be malicious. In doing so, she also selfishly disregards the idea that anyone besides her might desire something better in life.
Note the language of consecration and profanation that Cathy attributes to her books. The books are "consecrated" to her because of their association with her father and Thrushcross Grange, but Hareton's mere attempt to read from the books "profanes" them. This language underscores Cathy's contempt for Hareton as beneath her because of his lack of education. However, it also sets up a surprising twist in Cathy and Hareton's relationship later, when Cathy will soften enough that she's actually willing to teach Hareton to read.