Vampire anime incorporates many things from the traditional vampire lore, but the interpretations – just like in vampire fiction – vary from one anime to another. There are the irresistibly beautiful vampires who mean no harm to humans – a select few individuals aside, who eventually lose their minds and end up dead one way or another – and the outright villainous ones who indulge in blood drinking and view humans as nothing more but food. Two examples of such differing interpretations would be the very popular anime Vampire Knight and its follow-up Vampire Knight Guilty versus Shiki. The former portrays a high school setting with a Day Class which is meant for humans and a Night Class which is meant for vampires. Both coexist peacefully and all of the humans seem to be falling in love with the vampires.
The vampires in Vampire Knight don't drink blood from living humans, instead using an artificially generated substitute. Shiki, on the other hand, depicts vampires as careful and cruel plotters who will stop at nothing to feed. In fact, they cannot live without drinking from humans regularly. If they attempt to do it, they risk losing their mind because of a horrible thirst that will eventually drive them insane.
There is, of course, also the golden middle – two radically different vampire groups fighting each other. Usually, the goal of one is to enslave the humans, while the other group – most of the time the aristocratic old vampires – fight to protect the humankind from their severely inferior and blood-crazed brethren. The good tends to triumph in all of the cases.
Anime primarily not based on the theme of vampirism can have vampire cameos as well, and even there the interpretations of vampires can be radically different. An excellent example is the anime D.Gray-man which is focused on a group of elite soldiers battling demonized monstrous versions of human souls has a vampire whose special ability is to either extract the demonic virus from those monsters or contaminate them with his blood – the monster's death is the usual outcome.
Another example would be CLAMP's Tsubasa Reservoir Chronicle where a vampire can only feed from one single person for the rest of his or her life. What happens when the human in question dies is not specified, but we can guess at the possible scenarios. A very common complication of the plot in many a vampire anime is when a vampire who has sworn himself off human blood has to accept it to survive – or save the human in question.
More often than not, it also serves as a build-up for a very complex relationship. Rarely does it end with the human being turned into a vampire. One notorious example of deconstructing this plot was in the anime Hellsing where the main vampiric hero of the same name turned a dying human girl into a vampire without showing the slightest romantic inclination toward her.
All in all, classifying vampire anime isn't the easiest task because of such diverse interpretations. But it is indeed an interesting thing to watch - especially if you're a fan of the whole vampire genre. And I encourage you to check it out as soon as you can.
" Mom. I have something to tell you. I’m undead. Now, I know you may have some preconceived notions about the undead. I know you may not be comfortable with the idea of me being undead. But I’m here to tell you that undead are just like you and me … well, okay. Possibly more like me than you." -- Simon, City of Ashes