Rose Maylie is Oliver's aunt. Even before this fact is revealed later in the novel, Rose is close to Oliver, nursing him back to health after his botched burglary. It does not matter to her that Oliver has almost committed a crime or that he is an orphan from the streets: his vulnerability and loneliness call out to her.
Rose likely feels such an instant connection with Oliver because she herself exists on the margins of proper society. She has no idea who her parents were and fears she might be of illegitimate birth. This keeps her from marrying Harry Maylie, her true love, until the end of the novel.
Rose is also set up as a foil for Nancy. While Rose is pure and refined, Nancy is a prostitute and pickpocket. Rose's goodness serves as an inspiration for Nancy, who regrets what she has become and seeks to redeem herself by saving Oliver from a criminal fate like hers.
Not one of the more popular Dickens characters, Rose has often come under fire from feminist critics. As with A Tale of Two Cities's Lucy Manette and The Old Curiosity Shop's Little Nell, Rose is often criticized as too idealized to be interesting. For both this reason and her secondary-character status in the novel, Rose is usually cut from most theatrical and cinematic adaptations of Oliver Twist.