Martha is Little Em’ly’s childhood companion who flees to London and becomes a prostitute after committing a social transgression that, while not explicitly stated, is implied to be an affair. She is a key character in the second half of David Copperfield because she is instrumental in helping David and Mr. Peggotty track down Little Em’ly after she runs away from Steerforth.
Readers first encounter Martha when David and Steerforth notice a “haggard” and shabbily dressed young woman braving the bad weather to trail behind Little Em’ly and Ham as they walk down the Yarmouth streets. Steerforth remarks on the sight and refers to Martha as Little Em’ly’s “black shadow.” As the chapter progresses, David learns that Martha used to be a respected member of the community but is now “trod under foot by all the town” after being implicated in a scandal. Martha is a Fallen Woman, a woman who lost her innocence and fell from society's good graces and a popular archetype in Victorian fiction. By initially describing Martha as Little Em’ly’s “black shadow,” Dickens foreshadows that Little Em’ly will soon follow in Martha’s footsteps and become a Fallen Woman herself.
Interestingly, Martha is not villainized within the narrative, despite her Fallen status. On the contrary, Dickens appears to have nothing but pity for Martha and is sympathetic to the nuances of her situation; the moment during Chapter 47 in which David and Mr. Peggotty save Martha from jumping into the river is a tragic scene in which all of the characters involved lament the suffering that Martha has endured to bring her to such a drastic point. Dickens characterizes Martha as a kind and empathic soul who saves Little Em’ly because Em’ly was the only person who treated Martha with any kindness after she was ostracized from society. Ultimately, Martha is rewarded for her innate goodness: she is able to start a new life in Australia with Mr. Peggotty, Little Em’ly, and Mrs. Gummidge, and marries a farmworker. Through Martha, Dickens argues that Fallen Women are often victims of society, and worthy of forgiveness and support. It is worth mentioning that Dickens was not just sympathetic to fictional Fallen Women; in real life, he founded Urania Cottage, a shelter to help rehabilitate prostitutes, in 1847.