| Quote #4
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! (7.69)
Even early on, Heathcliff's desire for revenge competes with his love for Catherine. Revenge is one of the emotions that drives Heathcliff and gives him a reason to live. The fact that Hindley dies before Heathcliff allows him to inherit Wuthering Heights.
| Quote #5
It expressed, plainer than words could do, the intensest anguish at having made himself the instrument of thwarting his own revenge. (9.12)
Rescuing Hareton from death, Heathcliff recognizes that his instincts prevented the perfect punishment for Hindley – the death of his heir. Because he rescues Hareton, Heathcliff has to work a lot harder to get back at Hindley.
| Quote #6
I meditated this plan – just to have one glimpse of your face, a stare of surprise, perhaps, and pretended pleasure; afterwards settle my score with Hindley. (10.60)
Heathcliff is driven unequally by two aims: love and vengeance. Catherine knows that Hindley deserves Heathcliff's vengeance (because she was a victim of it as a child), and so she never intervenes on his behalf.