Heathcliff was an orphan and was raised by Hindley and Catherine's mother. Later, he became close friends of their father that brings on jealousy and anger with Hindley being sent to boarding school.
THE DEATH OF CATHERINE
When their father dies and Hindley went home. They already developed a bond between each other. Hindley now has all the power in the house because of their father's death. Heathcliff was reduced to a servant and Catherine was being taken away by the Linton's. Heathcliff was furious and seek revenge.
THE END
Years have passed, and Catherine is married to man named Edgar Linton. Furthermore Heathcliff is now married to Isabella Linton. Heathcliff moves back to Hindley
Catherine and Edgar have a baby girl but Catherine passed away in child birth. When Hindley heard the news he was heartbroken and vows revenge on Edgar.
Heathcliff finally got revenge on Linton. Later on his son married Catherine's daughter and since they have two blood lines his son control's both families. Illogically , the day of his death is the same as his wedding day.