The vampire stays indiscriminately bloodthirsty and ruthless until Anne Rice's Interview With a Vampire. The one vampire (Tom Cruise's character) is mostly legit: he has no problem killing but craves a "friend," or "bro" in today's parlance. So he turns a down-on-his-luck man (Brad Pitt) into a vampire. Unfortunately, he proves to be one with a conscience and is reluctant to attack humans for food.
But you gotta do what you gotta do, right? And if that means seductively sucking blood from a beautiful woman's neck, so be it!