Didn't you take notice of the storyline for Haukke Manor? Lady Amendine had virtually became a vampire after making a shady deal with the Void/Ascians (or at least, she was a thinly-veiled Madame Bathoy copy in that she was drinking blood from her maidservants in an attempt to regain her beauty) - although she looked more like a succubus, the connection was clear.

FFXI also has vampire enemies, although they were a special genus of undead who only appeared as a boss monster (which curiously was absent from that FF Wiki list), so it's like ARR will also feature a similar family of enemies to fight. All we need is a whip class in the game to compliment it.