Bram Stoker, author of the novel "Dracula," never makes the origin of Dracula explicit. Van Helsing implies that he made a deal with the Devil and used necromancy to make himself immortal. In the book, Dracula is introduced as an old man, but he grows younger as he consumes blood.
Stoker's inspiration for the character Dracula was the medieval Transylvanian ruler Vlad Tepes, nicknamed Vlad Dracul, which means "devil" or "dragon." Tepes was not a vampire in Transylvanian legend, but vampires were a prominent part of the cultural lore. It is likely that Stoker wanted to juxtapose Tepes with the vampire myth but did not like the typical Transylvanian origins: red hair, cats jumping over the dead body, suicides and witchcraft, for instance. Instead, his Dracula took charge of his eternity and worked with dark forces to attain immortality.