In the novel Frankenstein by Mary Shelley, the character of Justin Moritz refers to a servant in the Frankenstein estate who became a confidante and friend of Elizabeth. The quote that you can find as to why she arrived at the Frankenstein estate is as follows (as told by Elizabeth herself:
Madame Moritz, her mother, was a widow with four children, of whom Justine was the third. This girl had always been the favourite of her father; but, through a strange perversity, her mother could not endure her, and, after the death of M. Moritz, treated her very ill. My aunt observed this; and, when Justine was twelve years of age, prevailed on her mother to allow her to live at her house.
So basically Justine was morally abandoned by her mother and Elizabeth's aunt rescued her. Another thing about Justine is that she was in a weak position as a servant, for which she became falsely accused of killing William and was executed for it to the dismay of the Frankenstein clan, whom embraced her as family, educated her, and treated her as a favorite. They also were convinced of their innocence.