At first, Cathy is despondent about Linton's departure. As time passes, though she asks about Linton less and less. Meanwhile, Nelly keeps tabs on Linton by questioning the Wuthering Heights housekeeper, and learns that Linton remains weak and whiny and that Heathcliff can't stand him.
Just as Catherine seemed to take on the "masculine" role in contrast to Edgar, Cathy is portrayed as strong while Linton is weak and "feminine."
One day, three years after Linton goes to Wuthering Heights, the sixteen-year-old Catherine and Nelly go bird-hunting on the moors. Cathy runs ahead of Nelly, and when Nelly catches up she finds Catherine speaking with Heathcliff and Hareton.
Like her mother, Cathy enjoys the moors. And it should come as no surprise that when she goes to enjoy nature, she encounters Heathcliff and Hareton.
Catherine says that she thinks she's met Hareton before, and wonders if he's Heathcliff's son. Heathcliff says no, but that he does have a son whom Catherine has met before and invites Cathy and Nelly to come back to Wuthering Heights with him. Nelly suspects Heathcliff's is plotting something, but Cathy is intrigued and Nelly has no choice but to go along with her to the Heights.
It should come as no surprise that Cathy would think that Hareton is Heathcliff's son. Because Heathcliff has treated Hareton just as Hindley once treated Heathcliff, Heathcliff and Hareton are extremely similar to each other.
At the house, Heathcliff tells Nelly that he hopes Linton and Cathy will one day marry. Yet Cathy and Linton don't even recognize each other when they meet.
Heathcliff's plot becomes clear: he wants to marry them in order to solidify his claim to Thrushcross Grange.
Linton, is now taller than Cathy. But he is still so sickly and weak that he can't even show Cathy around the house, so she goes off with Hareton instead. Heathcliff demands that Linton go after them. Before they move out of earshot, Nelly hears Cathy mocking Hareton for being illiterate.
Like Catherine before her, Cathy is caught between the worlds of nature and civilization. Linton is too sickly to keep up with her, but she is too judgemental and class conscious to regard Hareton with anything but contempt.
The next day, Cathy confronts Edgar about why he has kept her relatives at Wuthering Heights a secret from her. Edgar tries to carefully explain, and though Cathy doesn't entirely understand he does manage to get across how much he despises Heathcliff. Edgar also asks his daughter not to have any contact with Linton, but Cathy doesn't listen and she and Linton begin writing secret letters to each other. Nelly eventually finds Linton's letters and, over Cathy's objections, destroys them. Cathy ends the correspondence with Linton, and Nelly doesn't say anything about the letters to Edgar.
Yet there is something in Linton that clearly attracts Cathy. Looking back at the first time the two of them meet in chapter 19, when Cathy babies the sick Linton, it may be just that—by being so sick, Linton makes Cathy feel like a strong and powerful mother. Whatever the attraction, Heathcliff's plot seems to be working.