What Causes Post-Dramatic Stress Disorder?

The entire harry potter series, which is the battle against evil, in case you didn't notice, i mean, that's v Voldemort, right? He's satan for all intents and purposes. In order for harry to finally defeat valdemore, he has to die and be reborn. That's how the book ends. And there is something to this idea of the dying and resurrecting hero. It makes great enough so that tens of millions of people spend billions of dol s on it.