Prismatic Baron said:
Even so, vampires being demons or not is kind of universe specific. Like dragons, every universe sets its own rule on the matter.
Edit: For that matter, what a demon is changes based on universe. I'm not sure why so many people complain about Twilight vampires not being vampire-y enough, like we have something in real life to compare it to. Heaven forbid someone has a creative take on a make-believe creature for their fictitious story!
True, what they are changes based on universe, but there are some characteristics of fantasy creatures that have to stay the same or else they become a different creature entirely. For instance, what if Bioware decided to say that the Asari (Mass Effect) were vampires and didn't actually elaborate on that until halfway through the game, and even then expected you to already know it? You'd scratch your head, with a very puzzled "what the fuck?" going through your head.
Fictional creatures that are in many different stories must have some traditional characteristics; vampires must drink people's blood and turn others into vampires, they must have a weakened state or suffer outright death in the sun, they must be able to take far more damage than humans, etc. Twilight vampires are not "vampire-y" enough because, from what my (thankfully) unlearned mind can tell, they don't seem all that threatening. The very idea of a blood sucking, night stalking creature who looks human is terror-inducing; Meyer has turned it into a cheesy, sappy love story with all the character of a knockoff soap opera.
To answer the OP's question, I have a strong suspicion that Twilight was a huge knockoff of this [http://en.wikipedia.org/wiki/Underworld_(2003_film)]. And, in fact, if you want to watch a better version of it, you don't even need to make it. Just watch that. It's not perfect, but vampires do come across as something to be feared, not boyfriends to be had; though boyfriends are had in that story, there's a bigger overarching story involved.