For all his roughness of birth in the novel 'Wuthering Heights' by Emily Bronte - Heathcliffe has the intelligence of the oppressed, the watchfulness of the exploited - he has learned like many mistreated individuals to be an opportunist. These people learn early in life that there is no love, no care and that the only person they have in the world to look out for them is themselves. This is sad but,for some people who become sociopathic, callous and cold as a result - inevitable. Apart from the love he thought Catherine had for him until even she mocked him - he has no love. He learned to watch for opportunities and sees a mega big one in Hindley. He sees his Achilles heel - the dissipating weakness which will empower and enrich himself. He watches the enemy drink and gamble his way to destitution - looking as if he is helping but in reality waiting for the final fatal moment to strike without mercy, winner taking all. Such is the nature of the beast - Heathcliffe!
In the novel “Wuthering Heights” Heathcliff has been badly mistreated by Hindley, his foster brother. He is in love with Catherine, but he overhears her telling Nelly that Edgar Linton has asked her to marry him. She also applies that Heathcliff is dirty and unrefined. Heathcliff rides off into the night. Catherine marrys Edgar and moves with him to his estate. Heathcliff returns changed. He has made his fortune, even though no one knows how. He has also become elegant and cultured. Hindley had lost his wife in after the birth of their son. He has become a mean drunkard. He has also drunk up his inheritance and is in need of funds. Heathcliff has money and a new presence to him. Hindley allows him into his home because he needs funds. Heathcliff begins to take over control of the estate and even beats Hindley. Hindley hates him but needs the means to buy drink.