If Heathcliff can be considered the main protagonist of the novel then Catherine Earnshaw is the dominant female spirit which prevails the novel. She is a character dominated by obsession and her single greatest obsession is her love for Heathcliff. It is this which gives food to her soul, which controls her life and gives a sense of meaning, purpose and direction to her existence. The love which she professes for Heathcliff is not mere romantic love; neither is it based on mere physical attraction, it is an identification, a union of souls-: "Without Heathcliff" she says "the universe would turn to a mighty stranger". She contrasted the love that she professes for Heathcliff with that she publicly exclaimed for Edgar-: "My love for Edgar is like the foliage in the woods: time will change it, I'm well aware, as winter changes the trees. My love for Heathcliff resembles the eternal rocks beneath: a source of little visible delight, but necessary. Nelly, I am Heathcliff". Catherine's relationship with Heathcliff was established in childhood, Nelly remarked-: "The greatest punishment we could invent for her, was to keep her separate from him".
Catherine possesses a wild, passionate nature which initially is presented when she spat at Heathcliff on discovering that he was the reason for her father loosing the whip she was to get. Further evidence of Catherine's wildness can be seen from the pledge she and Heathcliff made-: "promised fair to grow up as rude as savages" in response to the terinay of Hindley. It was as Nelly said-: "one of their chief amusements, to run away to the moors in the morning and to remain there all day, and the after punishment grew a mere thing to laugh at." Catherine is defiant of authority and seemed to enjoy the wrath of others-: "she was never so happy as when we were all scalding her at once" Catherine's passionate nature, evident throughout her childhood, seemed not to exist in her early months of her marriage to Edgar. Her passion was described as-: "gunpowder which lay as harmless as sand because no fire came near to explode it".
While Catherine is wild, wilful and passionate, she also possesses a double character. Her five week sojourn at the grange awakens in her an appreciation of the civilised world. When she returns to the Heights, both manner and appearance have changed and is shocked in appearance of Heathcliff and Edgar. From then on, Catherine adopts a split personality - an amusing lady-like disposition in the company of the Lintons and returning to her wild passionate self when accompanied by Heathcliff. She declared her wish to be 'the greatest lady in the neighbourhood" as the materialistic side to her personality begins to assert itself. For the first time in the novel, Catherine worries how others see her and she confesses to Nelly it would degrade her to marry Heathcliff. The duality of Catherine's character revealed a crisis point with her marriage to Edgar - the one event in the novel above all others which determines the futures of the central characters. Catherine's marriage to him is a betrayal of her nature. Not only has she broken with her kindred spirit, Heathcliff, but she has physically removed herself from the wildness and freedom from the Heights and the crags. This choice made by Catherine favoured wealth, civilisation and social position over her natural affinity with the untamed, uncivilised world represented by Heathcliff.
Catherine's marriage to Edgar and her rejection of Heathcliff is a rejection of herself. In going to the Grange, she has turned her back, not only on Heathcliff, but on the carefree lifestyle she enjoyed at the Heights. In comparing their souls, she said of Heathcliff-: "his and mine are the same and Linton's is as different as is moon from lightning or frost from fire." Before she died, she came to terms with her error, recognised she would only be at peace-: "not among the Linton's,...under the Chapel roof, but in the open air". The error committed by Catherine in marring Edgar is one of which she was fully aware-: "I'm convinced I'm wrong - I've no more business to marry Edgar than I have to be in heaven" She also recognises that her heaven is not a traditional one but rather one out on the moors with Heathcliff. In the delirium she suffered before death, she longs for that freedom-: "I wish I were a girl again, half savage, hardy and free" However, it is then too late. The return of Heathcliff after a three year absence is a catalyst which arouses her true nature. On his visits to the Grange, it is noticeable that a table was set for he a Catherine, and another for Isabella and Edgar, symbolising the gulf between them and the fact that Catherine occupied an unnatural position in this civilised world.
A significant feature of Catherine's character is her wish to dominate both situations and people. When she wants to be alone with Edgar on one of his visits to the Heights, she pinches Nelly in exasperation and then delivers her a stinging blow when Nelly refuses to leave the room. When Heraton cries put in fear of Catherine, her response was to shake him-: "'till the poor child waxed livid" She refuses to allow Edgar to leave after witnessing this event-: "I should be miserable all night, and I won't be miserable for you" Nelly recalled that Edgar-: "possessed the power to depart as much as a cat possesses the power to leave a mouse half killed" Later on, she orchestrates a fight between Edgar and Heathcliff and throws the key into the fire when Edgar attempts to leave. She described Edgar, her husband, as 'a sucking leveret'. Catherine's domineering personality resulted in her every whim being catered to at the Grange. Nelly recalled that Edgar had-: "an inept rooted fear of ruffling her humour" The author uses nature imagery to emphasis the extent of her dominance-: "it was not the thorn bending to the honeysucles, but the honeysucles embracing the thorns" Although Catherine is a domineering, wilful, she displays a certain naiveté throughout the novel. The main example of this is of course the self deception that is her marriage to Edgar. She is naive because she believes that her marriage will actually advance her relationship with Heathcliff. The position she will have as mistress of the Grange and Mrs. Linton will allow her to raise Heathcliff up from his lowly position and -: "place him out of my brothers power" In her innocence, Catherine believes she can keep both men, on Heathcliff's return believing that he and Edgar could be friends.
Catherine's illness and death represent perhaps a natural and predictable result of her movement from the Heights to the Grange, by not staying true to her nature and by swapping the outdoor life that she had with Heathcliff for the role as the lady of the manor. She has in a sense cut off her own oxygen supply, instead of the wild air of the moors she now breaths the stifled air of the Grange, like a flower without light she eventually withers and dies, a situation entirely of her own making. Having rejected Heathcliff in favour of marriage to Edgar, she was found by the society in which she lived, once this course was chosen there was no going back, although she realised the error of her ways, she had placed herself in a situation in which death could only extricate her, therefore she was buried at the edge of the kirkyard where the border between it and the surrounding moors was ill-defined. In death, she had returned to nature and regained her freedom, the dire consequences of her failure to remain loyal to her true self.
A significant feature of Catherine's character is the influence she continues to have after her death, like Heathcliff she has a troubled spirit which torments Heathcliff to the point of madness and even to his own death.