." One night, it is revealed to Nelly Dean, a servant at Wuthering Heights and the primary narrator of the novel, that Isabella has run off with Heathcliff, although Edgar has warned her that, if she does so, he will cut off all ties with her. After several months, Heathcliff and Isabella marry, but she soon realises her mistake, sending a long letter to Nelly in which she details her hostile and displeasing "welcome" at the Heights, and her hatred for Heathcliff, who has made it clear that he has married her only because he is now the heir to the Grange. Isabella is reduced to the status of the abused, hurt and degraded wife, and Nelly describes Heathcliff as looking like "the only one decent" in the household, while Isabella has seemingly lost the title of Miss Linton of Thrushcross Grange. Isabella continues to despise her vengeful, tyrannical husband, and, at the death of Catherine, taunts Heathcliff by insisting that her death was entirely his fault. She also points out that Hindley Earnshaw, Catherine's drunken brother and Heathcliff's greatest enemy, has the same eyes as her, despite Heathcliff's relentless attempts to "gouge them out". This provokes Heathcliff to a deep and passionate anger, which results in yet another brawl between himself and Hindley.Isabella was actually attracted by heathcliff brutality until she herself suffered from it. Her infatuation with Heathcliff comes across as both risky and silly. Like a fool, she yearns to be with Heathcliff and confesses to Catherine, "I love him more than ever you loved Edgar, and he might love me, if you would let him!" (10.79). Heathcliff tells Catherine:
And I like her too ill to attempt it [. . .] except in a very ghoulish fashion. You'd hear of odd things if I lived alone with that mawkish, waxen face: the most ordinary would be painting on its white the colours of the rainbow, and turning the blue eyes black, every day or two: they detestably resemble Linton's. (10.121)
Isabella finally wises up and leaves for London, but not before getting pregnant with Linton Heathcliff, who winds up with both of his parents' worst qualities.
In Ch10 we learn that Isabella has become infatuated with Heathcliff. "The attachment rose unsolicited and was bestowed where it awakened no reciprocation of sentiment." The elder Catherine warns Isabella, "Heathcliff is a fierce, pitiless,wolfish man...and he'd crush you like a sparrow's egg." But Isabella goes ahead and elopes and gets married to him. In no time Isabella is cured of her infatuation,"Is Mr.Heathcliff a man? If so, is he mad? and if not, is he a devil?"Ch13. Finally, in Ch17, she escapes from Heathcliff who almost kills her and seeks shelter in Thrushcross Grange.
Isabella and Heathcliff's marriage is characterised by so much of violence and hatred because Heatchliff never was in love with her. There is place only for the elder Catherine in his heart. But he marries Isabella to wreak his vengeance on Edgar who has married the elder Catherine. At the same time he emphatically tells Catherine that he does not intend to marry Isabella to make her jealous "I seek no revenge on you" Ch11.
The scheming Heathcliff has another reason for agreeing to marry Isabella:once Edgar dies Thrushcross Grange will pass on to Isabella and thus indirectly to him, "She's her brother's heir, is she not?"
Given such a combination of circumstances it is not surprising that both Isabella and Heathcliff try to kill one another in Ch17: "he snatched a dinner knife.....a little deeper than his missile."