The choices that Heathcliff makes in this novel are mostly the result of the treatment that he has himself received from various members of the Earnshaw and Linton family, which has produced in him a desire for revenge that is so great that it seems to possess his very soul. Of course, another cause that drives him to act the way he does is his love for Catherine, which calls him back to the moors after his long absence and brings the two characters together again.
If we examine the novel, the early chapters are full of ways in which Heathcliff from a very early age is mistreated by Hinton and scorned by Edgar and Isabella. The final straw for Heathcliff is overhearing Catherine tell Nelly in Chapter Nine that it would "degrade" her to marry Heathcliff. This triggers his departure from Wuthering Heights and his disappearance from the action for a while. However, when he returns, he deliberately sets himself on a course of revenge against both the Earnshaws and the Lintons. He buys out Hinton and owns Wuthering Heights and then treats Hareton, Hinton's son, in exactly the same way that he himself was treated by Hinton. At the same time he delibertely tries to get back at Edgar by marrying Isabella. There is nothing more profound in these actions than Heathcliff's revenge and his intense desire to hurt those who have hurt him.