Where in the blue blazes did Elizabeth come from? Dracula's niece? Huh!? : x
This is another theory of mine that I was going to write into its own separate article, but I supposed here is as good a place as any.
Elizabeth Bartley - the "niece" of Count Dracula who was introduced in Castlevania Bloodlines, and based on Erzsébet Báthory from Hungarian history. In the games, she is a vampire who associates with Dracula as her uncle, and was executed in the early 1600's for vampirism, and later resurrected by the witch Drolta Tzuentes in the early 1900's. How does she fit into the scheme of things?
It is said Mathias "became" Dracula at some point before Dracula's Curse in 1476 (which is the historical year the real Vlad Tepes "died", so the timeframe is the same), and Vlad Tepes had several brothers, at least two of whom reached adulthood. It could be said that either of these brothers of Vlad sired offspring, making them the nephews and nieces of Vlad himself. Therefore, Elizabeth could very well be a niece of the human Vlad Tepes, several generations removed. Mathias taking over Vlad's life/stealing Vlad's lifeforce would make Elizabeth's claim still hold some validity, especially since the historical Bathory's uncle was a Voivode (governor) of Transylvania - which Vlad III had been at one point as were his brothers after him.
Elizabeth Bathory was historically a countess who married the son of a Baron and managed his estates while he was away. He ended up supposedly dying while at war with the Ottomans and she inherited everything. Now, according to the Castlevania timeline, this timeframe would be between the games Castlevania: The Adventure and Belmont's Revenge. Bathory/Bartley would have been a very influential person in the same area that Dracula would be in - having fled the battle with Christopher Belmont and biding his time until his power grew back. Dracula would need minions and power, and here was Bathory/Bartley - having the land, power and influence he could use. It would be nothing for Dracula to present himself to Elizabeth, claim familial relations to her in order to coerce her aid, and turn her into a vampire. She supplies him with servants and shelter for him to recover his power, and he turns her into a immortal bloodsucker. Win/Win for them both.
This would also coincide with Bathory's reign of terror in Hungary beginning just after Dracula's defeat in Belmont's Revenge. A few years after Dracula's death at the hands of Christopher in 1591, rumor begin persisting around Hungary of horrific torture and blood-draining Bathory was committing against the daughters of lesser nobility who had placed them in her care in order to teach them, as well as the murder of several maids and other female servants in her castle of Čachtice. She convicted of the murders and died in early 1600's. Historically, Bathory died after years of house arrest in a set of walled-up rooms. The Castlevania history lists Bartley of dying around the same time, but of being burned at the stake after being discovered as a vampire. Either way, after her death, somewhere between 100 and 200 corpses were found in the Čachtice castle - earning her the nickname "The Blood Countess".
Due to her starting out as a human member of nobility, then becoming a bloodthirsty vampire, in the Castlevania universe it wouldn't be hard to assume the "Bathory" name and "Bartley" name could have been separated (by Hungarian officials or covered up by the Vatican) in order to avoid the public from mass hysteria if they found out vampires existed.
THAT is my theory, anyway.