How we cite our quotes: (Chapter.Paragraph)
Quote #7
And from what I heard, Joseph contributed much to his deterioration, by a narrow-minded partiality which prompted him to flatter and pet [Hareton], as a boy, because he was the head of the old family. (18.78)
Though in the background, Joseph has his own role in perpetuating the drama. So it's not only Heathcliff and Hindley doing a poor job of raising Hareton—Joseph, a fairly minor character, plays a role too.
Quote #8
My son is prospective owner of your place, and I should not wish him to die till I was certain of being his successor. Besides, he's mine, and I want the triumph of seeing my descendant fairly lord of their estates; my child hiring their children to till their fathers' lands for wages. That is the sole consideration which can make me endure the whelp: I despise him for himself, and hate him for the memories he revives! (20.43)
Linton Heathcliff is merely a pawn in his father's grand scheme for revenge. Like the two houses that Heathcliff covets, Linton is a piece of property.
Quote #9
"These things happened last winter, sir," said Mrs. Dean; "hardly more than a year ago. Last winter, I did not think, at another twelve months' end, I should be amusing a stranger to the family with relating them! Yet, who knows how long you'll be a stranger?" (25.1)
Nelly indulges Lockwood's fantasy that he actually has a chance with Cathy Heathcliff. Why she does this is unclear. What's even stranger is that Nelly would think that this union would be a good idea. These people don't seem to marry outside the family.