Dora Spenlow is thought to have been inspired by Dickens' first love Maria Beadnell, whom he met in 1830.
Fairies and sylphs are mythological creatures of fantasy, and as David sees Dora as a fantasized figure, so did Charles Dickens see Maria Beadnell.
Maria Beadnell was inconsistent in her treatment of her suitor. Maria's public shunning of Dickens and her parents’ disapproval of the courtship prompted them to send their daughter to a school in Paris.
Later the married Maria Winter wrote to her former suitor, and the two arranged to meet. Despite Maria’s warnings that she was greatly changed in appearance, Dickens was shocked by the alteration time had wrought on her. They met only once more after that, and she became the model for Flora Finching in Little Dorrit (1855-1857).