"According to the account which Shelley gave to Byron and Medwin, he re-encountered in Naples the married lady who had proffered her love to him in 1816. She... informed him of the persistent though hopeless affection with which she had tracked his footsteps." -- A Memoir of Shelley, by William Michael Rossetti, (1886)
Something—nobody knows what exactly—happened in Naples in the winter of 1818 concerning Shelley and a baby girl. There is some question about how much of the whole story Mary Shelley ever knew, and she later suppressed the few details that were available.
During the winter of 1818/19 Shelley was living in Naples with his wife (Mary Shelley, the author of Frankenstein,) his wife's step-sister Claire, who was possibly pregnant, and a pregnant nursemaid. By the time he left Naples in February, he had taken financial responsibility for a new-born baby girl.
Until 1936, Shelley scholars had no information about the identity and even the confirmed existence of the little girl that Shelley referred to in a few surviving letters as his 'Neapolitan ward.'
Academics surmised that this ward was a foundling whom Shelley impulsively adopted to soothe this wife after the loss of their daughter Clara. Throughout his life, Shelley had strong impulses to “rescue” girls, so buying or otherwise obtaining an attractive Italian infant would not have been out of character for him. However, the baby Elena Adelaide did not become part of the family and was left behind in Naples, where she was evidently left with a working-class Neapolitan family.
The child remained “a vague wraith” (in the words of scholar Richard D. Altick) until Shelley biographer Newman Ivey White and an Italian professor combed through the Neapolitan archives and found a birth certificate for Elena Adelaide, listing Percy Bysshe Shelley as the father, and the mother as one “Marina Padurin.” We'll return to that name Marina Padurin later. There was also a baptism certificate, again stating that Percy Shelley was the father and the mother was his wife, Mary Godwin (which was, of course, Mary's maiden name). Also, sadly, there is a death certificate, for Elena Adelaide, like three other children associated with this family, died very young in Italy.
The parentage of Elena Adelaide is a mystery, and there are several theories, but wide agreement that Mary Shelley was not the mother of the child. She wasn't pregnant that winter. There is no record of her giving birth, and obviously, she wouldn't leave Naples and leave her new-born child behind to be raised by a foster family. So, if the documents claimed that Mary Shelley was the mother, the documents are false. It is possible that Mary Shelley didn't even know about these documents. However, Mary's journal records that she and Shelley had a "most tremendous fuss" when they left Naples. That was Mary's euphemism for a fight.
So who were Elena Adelaide's parents. Was Shelley really the father? Who was the mother? Was it Claire? Was it the nurse-maid Elise? Was it the mysterious lady?
\Next blog post, we'll take a closer look at the birth certificate
 page 104, Richard D. Altick, The Scholar Adventurers, Ohio State University Press, 1987.