Time passes. Mr. Earnshaw's health deteriorates, and he becomes even less accepting of Hindley's behavior toward Heathcliff. He sends Hindley away to college, allowing Catherine and Heathcliff to grow closer.
Heathcliff has now completely taken Hindley's place at the Heights. In Hindley's absence, Heathcliff and Catherine can grow closer.
As Mr. Earnshaw nears death, he becomes interested in Joseph's harsh and rigid religious beliefs. Meanwhile, to her father's dismay, Catherine is constantly going on adventures with Heathcliff and getting into trouble. Though she teases her father about this, she loves him deeply and is the one holding him when he dies.
Fire and brimstone religion is another common feature of Gothic novels. As Mr. Earnshaw fades, Catherine and Heathcliff live in a kind of paradise, adventuring in nature. Also note Catherine's tomboy behavior. She doesn't fit the stereotype of a genteel girl.
On the stormy night of Mr. Earnshaw's death, Catherine and Heathcliff console each other. They talk of heaven, imagining it as a beautiful place.
Another storm during a major plot event. Yet the storm doesn't scare Catherine or Heathcliff. Note how they think about heaven in terms of beauty, as if it is like nature. Also note their obvious love for one another.