Of the major themes in Wuthering Heights, the nature of love — both romantic and brotherly but, oddly enough, not erotic — applies to the principal characters as well as the minor ones. Every relationship in the text is strained at one point or another. Brontë's exploration of love is best discussed in the context of good versus evil (which is another way of saying love versus hate). Although the polarities between good and evil are easily understood, the differences are not that easily applied to the characters and their actions.
The most important relationship is the one between Heathcliff and Catherine. The nature of their love seems to go beyond the kind of love most people know. In fact, it is as if their love is beyond this world, belonging on a spiritual plane that supercedes anything available to everyone else on Earth. Their love seems to be born out of their rebellion and not merely a sexual desire. They both, however, do not fully understand the nature of their love, for they betray one another: Each of them marry a person whom they know they do not love as much as they love each other.
Contrasting the capacity for love is the ability to hate. And Heathcliff hates with a vengeance. Heathcliff initially focuses his hate toward Hindley, then to Edgar, and then to a certain extent, to Catherine. Because of his hate, Heathcliff resorts to what is another major theme in Wuthering Heights — revenge. Hate and revenge intertwine with selfishness to reveal the conflicting emotions that drive people to do things that are not particularly nice or rationale. Some choices are regretted while others are relished.
These emotions make the majority of the characters in Wuthering Heights well rounded and more than just traditional stereotypes. Instead of symbolizing a particular emotion, characters symbolize real people with real, oftentimes not-so-nice emotions. Every character has at least one redeeming trait or action with which the reader can empathize. This empathy is a result of the complex nature of the characters and results in a depiction of life in the Victorian Era, a time when people behaved very similarly to the way they do today.