At midnight, Catherine gives birth to a daughter, Cathy, two months prematurely. Catherine dies two hours later. When Nelly brings Heathcliff the news, he seems somehow to already know. He curses Catherine for the pain she's caused, then begs her to haunt and torment him for the rest of his life, even if it drives him mad, just so they can be together.
Heathcliff's love for Catherine seems to rise to a different plane, from powerful love to something supernatural. First, he seems to know already when she dies, and then he wishes for a life of torment rather than to be separated from her.
Edgar keeps watch over Catherine's body, day and night, while Heathcliff stays out in the garden through the night. Eventually, exhaustion forces Edgar to leave Catherine's side for a few hours, and Nelly allows Heathcliff to see the body.
Another contrast with Heathcliff. While Edgar eventually succumbs to exhaustion, as any normal person would, Heathcliff never does any such thing.
After Heathcliff leaves, Nelly discovers that Heathcliff has replaced a lock of Edgar's hair that Catherine kept in her locket with his own hair. Nelly finds Edgar's lock of hair and twines the two together in the locket.
The combined locks of hair mark the two sides of Catherine's personality, the natural and the civilized.
Hindley does not attend Catherine's funeral, though he is invited. Isabella is not invited.
Once again, Isabella is treated terribly.
The nearby villagers are surprised when Edgar doesn't bury Catherine in the Linton tomb, but instead by a wall in the corner of the churchyard, with a view over the moors she loved. Nelly then tells Lockwood that Edgar is buried next to Catherine.
Linton's have been buried in their family crypt for generations. It's a "civilized," high-class place to be buried. But Catherine wants to be buried by the moors.