Heathcliff is the protagonist of Wuthering Heights. The action of the plot begins when he is brought into the Earnshaw household as a mysterious young child. His presence informs the events of the novel and affects the decisions of all the other characters. Soon after his arrival, Heathcliff begins to want to be treated like the equal of the Earnshaws and to be considered a legitimate suitor for Catherine. When Hindley treats him cruelly and unjustly, Heathcliff also begins to desire revenge. As he tells Nelly, “I’m trying to settle how I shall pay Hindley back. I don’t care how long I wait, if I can only do it at last.”

At the beginning of the novel, Heathcliff shows traits of hopefulness and kindness, but he becomes increasingly bitter and anguished, subjected by personal cruelties and class discrimination and deprived of Catherine, his true love. Eventually, his only motivation is his plan to gain control of both the Heights and the Grange. This plan drives him to work to bring Cathy and Linton together and to degrade Hareton. Heathcliff gradually becomes less motivated by revenge, finally admitting that he doesn’t even care about trying to cause suffering anymore. Heathcliff never wavers in his desire to be reunited with Catherine and only becomes more and more tormented by his longing for her. The last words he speaks are a lament that “it’s unutterably too much for flesh and blood to bear, even mine.” 

Heathcliff’s actions significantly change other characters, particularly Hareton and Cathy Linton. He succeeds in making Hareton an uneducated and lonely man who is ashamed of his ignorance. By forcing Cathy to marry Linton, he changes her from a sweet girl into an embittered young woman. However, their natural tendency towards love and kindness causes Cathy and Hareton to finally reverse these changes as they find first friendship and then love. Their change also seems to influence Heathcliff; once he accepts their feelings for each other, he seems finally able to let go of his quest for vengeance and surrender to a death where he can be reunited with his beloved.