Wuthering Heights: How does familial conflict reveal the protagonist's character?

Wuthering Heights is a veritable cacophany of familial discord, especially because it centers on two families becoming dysfunctionally intertwined through both loving and malicious marriages. The first conflict is between Heathcliff, an orphan who has been adopted by one Mr. Earnshaw, and Mr. Earnshaw's children, Hindley and Catherine. Hindley and Catherine are abusive and cruel to Heathcliff, who has become Mr. Earnshaw's favorite after the death of his wife. However, Catherine soon grows to love Heathcliff, and they become inseparable, further excluding Hindley. Catherine displays a judgemental and mean nature when Heathcliff joins their family, but ends up revealing a vivacious character and an affectionate disposition that continues to define her throughout the novel. At this point, we can't really assess Heathcliff's character; he is kind and doting with Catherine, but stoically endures the bile Hindley continually throws at him. 

Hindley is sent away to college, but after the death of his father, he returns to Wuthering Heights as its new master and forces Heathcliff to work in the fields like a common laborer. When his wife dies,Hindley turns to alcoholism, and his treatment of Heathcliff worsens. At the same time, Cathy has drifted away from Heathcliff-- she has accepted her social standing as a lady, and become engaged to Edgar Linton despite the relationship between her and Heathcliff. Heathcliff's reaction to this is to leave Wuthering Heights altogether, which shows that he has problems with moving on from concrete events (like Cathy's marriage) and that he has not accepted his circumstances in life. Consequently, upon Heathcliff's return, he begins exacting revenge on all those he feels have wronged him. He encourages the gambling and drinking of Hindley, who eventually dies and thus leaves the mansion to Heathcliff; he also marries Isabella Linton, Edgar's sister, in order to put himself in line for inheritance of Thrushcross Grange. However, Heathcliff still loves Cathy, and when she dies, he is anguished. Heathcliff's character is cunning and merciless towards those he despises, but he still has the capacity to love Cathy, suggesting that he is not a wholly evil character; also, the audience can empathize with him due to the nature of his treatment as a child. Throughout his life, Heathcliff continues to act cruelly towards those around him, including his own relatives. This indicates that he was mentally damaged by his childhood, and carried the effects of his abuse into his adulthood.