In Emily Brontë's Wuthering Heights, the two manor houses are symbolic of everything that is wrong with Heathcliff's life, and so will drive him fanatically to get what he does not have, but desperately wants.
Mr. Earnshaw adopts Heathcliff, rescuing him from the streets of Liverpool. While Catherine accepts Heathcliff, Lindley resents him terribly. While Heathcliff may have been saved from poverty, he is thrust into a situation that (in many ways) causes him more harm than good. Whereas he knew who he was and understood the life that he had on the streets, this home of plenty robs him of a sense of self—he never feels good enough. Rough around the edges, he is forever reminded of where he has come from.
Growing up, Catherine and Heathcliff spend a great deal of time on the moors; here they play and Heathcliff feels free. However, from the moment Catherine discovers Thrushcross Grange and the people who live there, Heathcliff is once again thrust out of the one environment where he feels safe, to once again feel isolated—completely alone.
In all of this, Heathcliff has fallen in love with Catherine, something that will remain with him for the remainder of his life. However, they will never marry, never be happy. When Catherine is hurt while she and Heathcliff are out gallivanting near the Grange one day, she is taken to Thrushcross. Here she meets Edgar Linton and his family, and for Catherine, a new world opens up to her—one that does not include Heathcliff. She remains there for some time as a guest, while she heals. In the meantime, Lindley (who has inherited Wuthering Heights at his father's death) forbids Heathcliff to have anything to do with Catherine.
When Catherine returns, she spends a great deal of time with the Lintons. Soon Edgar proposes. Catherine has a seemingly private conversation with the maid, Nelly, wondering if marriage to Edgar is the best choice. Nelly asks if she loves Edgar. She says:
...he will be rich, and I shall like to be the greatest woman of the neighbourhood, and I shall be proud of having such a husband.
Nelly points out that this is not love. Catherine speaks of Heathcliff who happens to be passing the room; and he hears only a portion of what Catherine has to say:
It would degrade me to marry Heathcliff now...
Heathcliff is still unpolished, uneducated. In light of Catherine's social ambition, he is not of her class. This is all he hears, and he makes haste to leave the manor, not to return for several years. However, the rest of Catherine's comment to Nelly is quite telling:
...so he shall never know how I love him: and that, not because he's handsome, Nelly, but because he's more myself than I am. Whatever our souls are made of, his and mine are the same...
The tragedy here is that Heathcliff leaves feeling worthless. Here, then, is perhaps the most central conflict of the story. Thrushcross has all that Heathcliff wants: Catherine. Wuthering Heights represents a place that becomes a living hell as Lindley belittles him and treats him like a servant.
Heathcliff will one day return, educated and rich, and will spend the rest of his life doing all he can to get Thrushcross Grange—the place that took Catherine from him—as well as Wuthering Heights. He will destroy countless lives in doing so, but will never find true happiness. Catherine will die young, and Heathcliff's release will only come at his death, buried next to Catherine—so their remains can mingle for eternity.