Emily Bronte likes to trick you, so read carefully.
If, like me, you read Wuthering Heights as a hormonal adolescent, you will, like me, have seen it as a gothic tale of love, tragedy and ghosts. I urge you to read it again, and consider the book in light of the following.
Heathcliff exerts a mysterious power over his readers. Women often think him charming, quite a hero; men think him scary. In defense of Heathcliff, many people point to his words to Nelly Dean, regarding a desire to crush worms, and his reference to his own 'moral teething'. "See!" they cry, triumphant, "he isn't really bad... it's a moral teething, and he inflicts cruelty without meaning to!" On the other side of this is the claim that Heathcliff was needlessly and deliberately cruel, as demonstrated by his strangling of Isabella's dog the night of their elopement.
Over all is the spectre of Cathy, haunting Heathcliff from the night of her burial, when he visits her grave, to the night of her husband's burial, when her ghost is laid to rest. (In the Penguin Classics edition this is Volume II, Chapter XV, p285). Of particular note is that when Heathcliff visits her grave some eighteen years after her death, her face is still recognisable: she has not decayed. "Ah" sighs the adolescent romantic, "the power of Love is such that she will wait for him, unchanged, till he should join her." So thought I, until my mind was disabused by the excellent lectures of Fred Langman of the Australian National University.
The first point of interest here is Heathcliff's moral teething. For a full discussion of this, dear reader, I refer you to John Sutherland's "Who Betrays Elizabeth Bennet?" Meanwhile, it suffices to say only that he is in his teething phase right through the second part of his life, after he returns from his mysterious three year absence. He never leaves his teething in the past, indeed he becomes worse, exacting revenge right to the last. So far we see Heathcliff as unrepentant. Or is he? Right at the end of his career, Heathcliff declares that he is unable to continue, that his plan of revenge leaves him unmoved. He doesn't repent, exactly, but at least he is not actively cruel.
Next there is the charge of cruelty. It's interesting that the charges laid against him are always the easily defensible ones. Nobody mentions poor Hindley, but they remember Isabella's dog. Do you remember Isabella's dog? Do you recall Nelly untying it so that it could run away yapping after the couple? That sounds to me (and to Fred) as though he tied up the dog to prevent it following and making a noise. If my intended bride had a yappy dog I'd certainly silence it before the elopement.
The biggest problem of all in Wuthering Heights is the ghost of Cathy. It appears first when Heathcliff almost opens her coffin the night of her funeral, haunts him for eighteen years until the death of her husband and on the night of his funeral, Heathcliff again disturbs her coffin. This time, he pulls the lid right off to see her well-preserved face staring up at him and he is, at last, in peace.
I have one very important thing to bring to your attention regarding this moving account of Heathcliff's nocturnal visits: early in the book, when Lockwood is walking around the moors, he sees the very church where Cathy is buried. He comments that it is a swampy, damp place, very low, and that it is said that the swamp preserves the corpses buried there. "Aha!" exclaims the rational adult reader. "I knew there was a reason!"
Now, I know you're just saying that to save face, but that's okay. You know now. Cathy's miraculous unearthing is the product of nothing more than the circumstance of her coffin being placed in a peat bog. From here, it is but a small step to the application of modern psychology to explain how Heathcliff haunts himself until the death of Linton. Doesn't that make you feel better?