Nell has a strong resemblance to Clara Peggotty from Dickens’s David Copperfield. In this case, she’s nursing father and child rather than mother and child. And she does not have to dance around the evil Murdstones. 

Nell is a housekeeper with benefits for Castor Willow, though she knows she can never replace his dearly departed wife in his heart. She is content with her role, and provides the central warmth for the Willow household as they deal with the dilemma of Joe in his bedroom mausoleum, and Castor’s failing health. She is Josephine’s rock.

Nothing is mentioned of Mr. Barley, and how Nell came to be the housekeeper for the Willows. However, there is reference to a vicious older brother who burnt young Nell with a poker. This turns out to be Cotter Sullivan when Black Jack Cuttle delivers the pot of gold.