Pumpkin_Eater said:
I think it's the duality of a monster that appears and acts human. The subtlety that a good writer can put into a blood sucking monster that plays classical music and reads poetry is almost limitless. The rules for how the curse works are increasingly poorly defined as different series add and remove things, so you it's a flexible archetype that you can manipulate to fit what you want to do as an author. If you compare Saya from Blood+, a traditional vampire like you'd find in an Anne Rice novel, Karin, and a twilight character they have very little in common in terms of strengths, weaknesses, and traits stemming from their vampirism. There's probably more to it, but that's all that really comes to mind for me ATM.
Yes, something like that.
Humans are appalled yet fascinated by the monster that seems to lurk just under the surface of their fellow men. Vampires were terrifying because they were the living (or undead) embodiment of the monster in control of the man. Blood was also pretty sacred in terms of things like religion and society, so the fact that Vampires drained your blood was also pretty chilling - it was akin to having your soul sucked out of your body and devoured by evil.
The recent sexual allure of vampires came about in how they actually feed and interact with humans. These Victorian European vampires are not terrifying, but seductive and tricky. They also embody immortality, which was slowly becoming an obsession in people.
Nowadays, it's the lure of the tragedy of newly formed vampires. These are usually people with the most to lose, and a lot of emotion. They get separated from the rest of humanity by their vampirism, so they feel excluded and solitary. Since that's a growing trend in today's society (that many of our youth are feeling isolated), the vampire is appealing because the benefits outweight the tragic loss of human contact. It makes them feel SPECIAL.
That and sex was ramped up to the nth degree in most modern vampire stories and games that most people enjoy reading, watching or playing vampires. That underlying feeling of isolation is still pretty prevalent, though.