This romance is short-lived: Ianthe is killed, her throat torn open by an attacker who injures Aubrey and leaves behind an unusual dagger.

Upon recovering, Aubrey learns that Ruthven has inherited an earldom and is engaged to his sister, and they are due to be married on the day that his oath will end.

In the following issue, dated May 1, 1819, Polidori wrote a letter to the editor explaining "that though the groundwork is certainly Lord Byron's, its development is mine".

Polidori transformed the vampire from a character in folklore into the form that is recognized today—an aristocratic fiend who preys among high society.

[3] Due to this influential aspect, Jan Čapek argued that "Ruthven’s excesses in Polidori’s tale reveal the landscape of modern, increasingly capitalistic class society to be laden with anxiety concerning the continuing power of the aristocracy, as though untouched by the social shifts in the wake of the industrial revolution.

Kept indoors by the "incessant rain" of that "wet, ungenial summer",[8] over three days in June the five turned to telling fantastical tales, and then writing their own.

Fueled by ghost stories such as the Fantasmagoriana, William Beckford's Vathek, and quantities of laudanum, Mary Shelley[9] produced what would become Frankenstein, or The Modern Prometheus.

"[12] That influence has extended into the current era as the text is seen as "canonical" and – together with Bram Stoker's Dracula and others – is "often even cited as almost folkloric sources on vampirism".

[16] Earlier adaptations of Polidori's story include the 1945 film The Vampire's Ghost starring John Abbott as the Lord Ruthven character "Webb Fallon", with the setting changed from England and Greece to Africa.

[17] Also, The Vampyr: A Soap Opera, based on the opera Der Vampyr by Heinrich Marschner and the Polidori story, was filmed and broadcast on BBC 2 on December 2, 1992, with the Lord Ruthven character's name changed to "Ripley", who is frozen in the late eighteenth century but revives in modern times and becomes a successful businessman.

[21] In 1988, American playwright Tim Kelly created a drawing room adaptation of The Vampyre for the stage, popular among community theatres and high school drama clubs.