You have identified a key theme in this excellent novel. What is more disturbing when we think about it is the way that revenge is passed on down through the generations and is used to harm and damage the lives of the young heirs of Thrushcross Grange and Wuthering Heights. It is clear that one of the principal characters who wants and gets revenge is Heathcliff, and in particular we see that he gets his revenge against Hindley, for example, by treating his son in precisely the same way that Hindley treated him, reducing Hareton to nothing better than an ill-speaking slave that is uneducated. Likewise he gets his revenge against Edgar by marrying his son to Edgar's beloved daughter and making sure that Cathy cannot be there for her father's death. This also enables Heathcliff to inherit Thrushcross Grange. Revenge is something that is shown to echo down throughout the generations.