Lockwood falls ill for four weeks.
Lockwood, like the Lintons, falls ill when exposed to nature.
Heathcliff visits him once during this time, after which Lockwood asks Nelly to tell him how Heathcliff made his fortune. Nelly doesn't know how Heathcliff made his money, but continues with her story.
As a man who earned his money, Heathcliff would be looked down upon by the old-money upper class who inherited their wealth.
For about six months after Catherine's wedding, everything is peaceful at Thrushcross Grange, largely because the Lintons do whatever the imperious Catherine wants.
Catherine's willfulness and Edgar's passive love means that Catherine takes on the dominant (i.e. typically masculine) role at the Grange.
Then one evening Heathcliff appears at the Grange. Catherine is almost frantic with excitement. Edgar is less pleased. He suggests they receive Heathcliff in the kitchen, but Catherine insists that they bring him into the parlor.
Catherine's love for Heathcliff is immediately apparent. Edgar tries to denigrate Heathcliff by receiving him in the kitchen, which is where one would meet with people of a lower class.
As Heathcliff enters the parlor, Nelly notes that he looks imposing, mature, and dignified, in contrast to his youthful roughness. Yet he still retains a kind of "ferocity" in his eyes.
Heathcliff has escaped the lower class "roughness" imposed on him by Hindley, but retains his wild nature.
As Edgar, Heathcliff, and Catherine talk, Heathcliff says that he returned hoping only to catch a glimpse of Catherine, exact revenge on Hindley, and then kill himself. But Catherine's joy at seeing him has changed his mind. Edgar, uncomfortable, interrupts to say that if they wait any longer the tea will get cold. As he leaves, Heathcliff shocks Nelly when he tells her that he is staying at Wuthering Heights at Hindley's invitation.
Heathcliff is a man of grand, reckless, wild actions, such as revenge and suicide. Edgar is a civilized man of comfort, and when Heathcliff's wildness makes him uncomfortable he tries to impose civilization through the ritual of having tea. Heathcliff staying at the Heights reminds the reader of his promise to get revenge on Hindley.
That night, Catherine awakens Nelly to tell her that she couldn't sleep from excitement. She says that she had praised Heathcliff to Edgar, but that Edgar had claimed to feel sick and even cried. Nelly advises Catherine to hide her feelings for Heathcliff and treasure her husband's love, but Catherine dismisses Edgar and Isabella as spoiled children. Nelly comments that it's actually the Lintons who humor Catherine.
Again Edgar takes on the weak, feminine role in his relationship with Catherine. Catherine, meanwhile, doesn't seem to understand the basics of love, and, like a child, also doesn't understand why she can't just have everything that she wants.
Catherine also tells Nelly how Heathcliff wound up staying at Wuthering Heights: he'd gone to Wuthering Heights to find Nelly and get information from her about Catherine. But instead he found Hindley in the middle of a card game. During the game it was clear Heathcliff had money, so Hindley invited him to stay. Heathcliff insisted on paying for the lodging.
It begins to be clear that Heathcliff plans to use his wealth to exact revenge on Hindley. This revenge also reflects the more general class struggle of the time, as the new money class was able to buy its way into high society by preying on the debts of the old money class.
In the following days, Catherine and Isabella often visit the Heights, and Heathcliff regularly comes to the Grange. Isabella soon develops a crush on Heathcliff. When she confesses it to Catherine, her sister-in-law warns her that Heathcliff is a fiend whom she should stay away from. Nelly seconds this advice, and adds that there are rumors that Heathcliff is lending Hindley money to support his gambling habit.
When Catherine describes Heathcliff as a fiend, she might better call him a force of nature. He has no remorse and is relentless, and Catherine knows that someone as civilized and gentle as Isabella will be broken by him.
The next day, Catherine humiliates Isabella by revealing her crush to Heathcliff when he visits. Isabella rushes from the room. Heathcliff expresses disdain for Isabella, but notes that Isabella must be Edgar's heir. Nelly thinks Heathcliff is plotting something.
Heathcliff wants to use Isabella to take revenge on Edgar. He plans to use the rules that normally keep the classes separate—inheritance—to steal the Grange from the Lintons.