 In December 1818 , the Shelleys travelled south with Claire Clairmont and their servants to Naples , where they stayed for three months , receiving only one visitor , a physician . In 1820 , they found themselves plagued by accusations and threats from Paolo and Elise <unk> , former servants whom Percy Shelley had dismissed in Naples shortly after the <unk> had married . The pair revealed that on 27 February 1819 in Naples , Percy Shelley had registered as his child by Mary Shelley a two @-@ month @-@ old baby girl named Elena Adelaide Shelley . The <unk> also claimed that Claire Clairmont was the baby 's mother . Biographers have offered various interpretations of these events : that Percy Shelley decided to adopt a local child ; that the baby was his by Elise , Claire , or an unknown woman ; or that she was Elise 's by Byron . Mary Shelley insisted she would have known if Claire had been pregnant , but it is unclear how much she really knew . The events in Naples , a city Mary Shelley later called a paradise inhabited by devils , remain shrouded in mystery . The only certainty is that she herself was not the child ’ s mother . Elena Adelaide Shelley died in Naples on 9 June 1820 . 
