She was the most winning thing that ever brought sunshine into a desolate house: a real beauty in the face, with the Earnshaws’ handsome dark eyes, but the Lintons’ fair skin and small features, and yellow curling hair. Her spirit was high, though not rough, and qualified by a heart sensitive and lively to excess in its affections. That capacity for intense attachments reminded me of her mother: still she did not resemble her[.]

Nelly Dean describes young Cathy's physical features and beauty as well as pointing out some personality traits. In fact, Cathy's physical and emotional qualities seem parallel as she represents a brightness and intensity in the Linton household. Nelly also draws some comparisons between Cathy and her mother Catherine, especially in Cathy's ability to make strong connections.

[S]he could be soft and mild as a dove, and she had a gentle voice and pensive expression: her anger was never furious; her love never fierce; it was deep and tender. However, it must be acknowledged, she had faults to foil her gifts. A propensity to be saucy was one; and a perverse will, that indulged children invariably acquire, whether they be good tempered or cross.

Here, Nelly describes Cathy's temperament, relating her softness and gentle ways, but also admitting Cathy's faults. Nelly accepts Cathy's sassiness and demanding ways as typical of most pampered children and counters that a good character balanced out her negative behaviors. According to Nelly, Cathy has only the best qualities of her mother.

I found plenty of entertainment in listening to larks singing far and near, and enjoying the sweet, warm sunshine; and watching her, my pet and my delight, with her golden ringlets flying loose behind, and her bright cheek, as soft and pure in its bloom as a wild rose, and her eyes radiant with cloudless pleasure. She was a happy creature, and an angel, in those days. It’s a pity she could not be content.

Nelly fondly remembers the innocence and joy that radiated from Cathy as they walked the edge of the moor on the day after Linton was taken to Wuthering Heights. However, Nelly also laments Cathy's discontent as she looked beyond the protected world her father had built around her for twelve years.

I saw she was sorry for his persevering sulkiness and indolence: her conscience reproved her for frightening him off improving himself: she had done it effectually. But her ingenuity was at work to remedy the injury: while I ironed, or pursued other such stationary employments . . . she would bring some pleasant volume and read it aloud to me. When Hareton was there, she generally paused in an interesting part, and left the book lying about

Here, Nelly Dean explains how Cathy feels sorry for making fun of Hareton Earnshaw’s attempt at learning to read, so she tries to encourage him to try again. While she does not come out and apologize for her mean behavior, she does genuinely try to make amends by inventing a plan to teach Hareton to read. This speaks to Cathy's generally good-hearted character.

[S]he glanced towards the master . . . and she grew serious for an instant, scrutinizing him with deep gravity . . . she turned, and recommenced her nonsense; at last, Hareton uttered a smothered laugh. Mr. Heathcliff started; his eye rapidly surveyed our faces. Catherine met it with her accustomed look of nervousness and yet defiance, which he abhorred.

Nelly Dean recounts that while Heathcliff tried to break Cathy's hopeful and gentle spirit, he did not succeed. Cathy's nervous but defiant actions in front of Heathcliff prove that she will not let Heathcliff break her down any further. Her friendship and eventual love for Hareton Earnshaw prove more powerful than Heathcliff’s revenge.