Is everyone either a vampire or not a vampire?
I really appreciate this question, since it allows me to distinguish one of the few differences between "actual" vampire slaying and "practical" vampire slaying that I'm aware of.
In both actual and practical vampire mythology there is often a "transition time" for vampires (i.e. when a vampire is feeding on a victim but the victim has not yet crossed over to vampire-hood themselves -- they are a bit of both) which can sometimes, I think, put us in a postition to wonder just what in the heck we're dealing with (and should, by the way, cause us to consider very carefully who we're extending our invitations to). So there's that aspect of your question to consider.
But I get the feeling that your question is really more about whether some individuals among us are objectively vampires, and others are objectively...om...not. And I'd have to say that my answer to that question is that, for practical purposes (which are our purposes) there are no "objective" vampires -- there are only those vampires that feed on us personally.
Are there horror-shows of human beings out there, born without conscience or soul? There could be...I'm not a psychologist or theologist and not here to argue the point (although I think there are) -- my interest as a practical vampire slayer is in the vampires I do have some say over in my life -- how I can make clear decisions about them, and how I can take effective actions to either evict them or make peace with them.
Your vampire may not be my vampire. I mean, I can't stand the sound of someone eating a banana in my vicinity -- it can just about ruin my day, you know? That may not be a vampire to you, but it sure is to me. Maybe your vampire shows up every time you're driving and the person ahead of you is driving"too slowly" and you can't pass them, or when your spouse walks through the door at night and fails to notice that you've made a gorgeous dinner...I mean, you've got yours, I've got mine. Nothing objective about them.
Then of course there is the aspect of the vampire within us all -- the one who is always hungering for more and more and more of what we refuse to acknowledge we've already been given (see Monday's post), or the one who tells us we're not rich enough, smart enough, handsome enough, or whatever enough to make it (ya loser!); or the one who criticizes, punishes, or minimizes the people we love (and who love us). These vampires fall into the "practical" camp, too.
Which makes them practically slayable, incidentally.
Does that answer your question?