Does Heathcliff suffer or does he inflict suffering?
As a child Heathcliff suffers from being the dark, orphaned boy that his father brought home to the chagrin of his son, Hindley. Then, as an adult he suffers the rejection of his beloved Catherine as she marries Edgar Linton. Heathcliff runs off, but later returns to wreak revenge upon those who have taken Catherine from him.
After Heathciff becomes a part of the Earnshaw family and is protected by Mr. Earnshaw, he and Catherine become fast friends, running to the moors and delighting in their imaginings. Hindley resents Heathcliff, treating him cruelly, and before his mother's untimely death, he has her support in this antipathy.
Perhaps one of the most humiliating experiences for Heathcliff is the time that he and Catherine peek in the windows of the Lintons and their dog bites Catherine. While Catherine is taken into the house to be attended, the Lintons do not like Heathcliff's appearance and forbid his entry. This rejection remains with Heathcliff. Then, after Catherine returns home, she tells Heathcliff he is dirty because he has let himself go in her absence, and he is deeply hurt again.
Later on, Mrs. Earnshaw organizes a dance, having invited the Lintons. Heathcliff is locked away from the guests by Hindley. When Nellie tries to feed him after he is released, Heathcliff tells her:
"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. I hope he will not die before I do!"
After Catherine tells Nellie that Edgar Linton has proposed marriage, Heathcliff overhears her, but misses the rest of Catherine's conversation with Nellie in which she declares that Heathcliff and she are almost the same person, she loves him deeply, but she knows that she must marry Linton. That night Heathcliff runs away. Later, Catherine takes ill after searching for Heathcliff outside in the rain. She is taken to Thrushcross Grange where she recuperates, and eventually marries Edgar.
Some years later, Heathcliff returns, appearing sophisticated and wealthy. Nellie suspects Heathcliff of harboring vengeful thoughts as he does nothing to discourage Isabella Linton's affection. Eventually, Heathcliff marries Isabella and acquires her property. However, when Catherine dies, Heathcliff becomes overcome with grief and rage. After tolerating all the abuse she can from Heathcliff, Isabella finally leaves him and gives birth to a son in London, Linton Heathcliff.
Catherine's daughter, who is also named Catherine, wanders one day from Thrushcross Grange and finds Wuthering Heights. Eventually, Heathcliff cruelly forces her to marry his son Linton so that Thrushcross Grange can belong to his family. This is what occurs when the sickly Linton dies and Edgar does, also.
Later, Heathcliff withdraws into his own personal suffering for Catherine Earnshaw of old, and he pays no attention to the younger people as young Catherine (Catherine Earnshaw's daughter) teaches Hareton to read and they grow to love one another. However, the tortured Heathcliff wanders the moors and calls to the ghost of Catherine.
One night Nellie finds Heathcliff wet from the rain as he has flung open a window. On his face is a "frightful, life-like gaze of exultation." Perhaps, at last the ghost of Catherine has visited him.
Actually, both are true. Heathcliff suffers and inflicts suffering. Heathcliff harbors a deep-seated pain. He passionately loves Catherine, who marries not him but Edgar Linton. And if that was not enough! Catherine dies and he becomes a monster, a tormented soul. He suffers all throughout the novel because of his unfulfilled wish to be with Catherine. In this way, he is an atypical Byronic hero, who is a hero with a dark, antagonistic side. Separation from and then death of his love brings about his destructive, revengeful side.
Now since it's Edgar and Hindley who, for him, are responsible for his separation from Catherine, he plots against them. He marries Edgar’s sister Isabella and tortures her to inturn cause suffering to Edgar. He cleverly takes Wuthering Heights from Hindley and makes his son Hareton lead a servant life after his death. He kidnaps young Cathy to acquire Edgar's property.