I read an interesting article on Patheos the other day that was talking about the rise of the PostModern mindset. Basically, religions (the big ones, anyhow) have had years to counter and explain the major scientific discoveries of the last century (evolution, size of the universe, Big Bang, etc.), but relativley little time to address the PostModern mindset, the new wave of "Why are we here?/What is our place in this world?" philosophies. For the longest time, it didn't matter if you asked these questions, because if you did, either you wrote it down and other intellectuals/philosophers would discuss it, and that was the sum total of your impact (in your current time, typically) or whatever religion you belonged to just "explained" it away. But now those quesitons have filtered down to the common person, and for the most part, we're not letting religions say, "Just becuase" anymore.
Because humans (generally speaking) seek meaning in their lives, we need to know if there's a point to our existance, and the wave of popular media relating to "other-worldly"-type creatures, re: vampires, wizards, werewolves, etc., I think is a direct reflection of this need. We can use this mythological/metaphysical creature/person to hold up a mirror to our own questions, while at the same time showing us a being who, in some cases, is fully aware of their purpose (a goal we all seek). By their very nature (or un-nature? I dunno), they are not quite human, and that allows us to distance ourselves from them mentally. That distance is very important because we then identify with the human traits we find in them, because we're looking harder for them. If these beings were Joe Schmoe down the street, or some serial killer on the news, we would shrug it off because we've seen it all before. But who has seen a vampire from Twilight? Who has seen the wizards from HP? Because of that, the fiction of it all, we are able to look closer into the looking glass...
Prime examples include the Cullen family (not including sparklemotion boy), who are fully aware of what they are, where they exist in the world, and what they should do. Despite the upheval wrought by Empty-Shell-of-a-Human-Girl, they are aware of what external forces influence their lives and are able to address them. There is also the Volturi (yes, I've read all the books and seen all the movies...I had to watch lots of violent movies to get my man-card back) are a very good example of certainty in a changing world. We see them in the books and movies as sort of a looming threat, but if you take it a step deeper, they are simply doing the most basic of human behaviors. They secure a safe place for themselves, and they seek to keep it. They probably go overboard, what with the, "let loose the psycho in Seattle so we can get some more powerful people with us" plan, but that's also part of it (more on that in a sec).
In the HP universe, we have characters like Dumbledore and Voldemort, two opposing forces, that while mortal (or mostly), fully acknowledge that they have power over their world, and exercise it as they see fit. The genius of Rowling's stories is that we can then, vicariously thru Harry, see that we, too, have the power to influence our world, and find our own place in it.
I think it curious that the ones who are typically so sure of themselves, their place, their desires, and their goals are often the villains of the story. The hero in these tales, who we are obviously supposed to identify with, is always uncertain, questioning, and searching for something like the surety displayed by their nemeses. So is the result of the tale that we, like the hero (even upon defeat of their enemy and all their certainty), are doomed to still question if we did the right thing, if we were right to declare, "This is what I will do, and to hell with the questions.", even if we still have them? Or is it that by gaining a surety in our lives, by knowing what we want, who we are, or even our place in the world, we in some level become a villain?
/ rant
Sorry, Wolfie, I think I out-ranted you. That ran on a little long.
Edit: It would help if I finished all my sentences. :P