Murder.

http://www.film-trip.com/strangerstrain2.htm
We all know Hitchcock has a deep fixation on murder. One of the world’s first and most prominent filmmakers, Hitchcock didn’t choose an easy route. Comedy, romance, and melodrama all had mass appeal at the time, but for Hitchcock, there was no other choice than suspense. If he didn’t seem like enough of an innovator, this was a time when the concept of movie genres was still being explored. It is thanks to Hitchcock that we even have horror, thrillers, and a number of other sub-genres we cherish today. It’s easy to conclude an analyzation of this theme by pointing to Hitchcock’s childhood and unresolved psychological issues. Of course in order to be a filmmaker of this kind (and of his caliber), he must have had some kind of personal motivation behind it. Murder isn’t an easy subject to dedicate your life’s work. But it wasn’t just Hitchcock, was it? He had an audience, didn’t he? Don’t we still love his films today? Doesn’t his genre (no matter how perverted) still hold sway over us?
In order to make the films he did, Hitchcock knew one thing: we’re all sickos. From Shakespeare to Poe, entertainers have always had a knack for pinpointing that special place in our heads where we harbor our inner psychopaths. While we want to stand up and scream “don’t go in there, you idiot!” yet we also can’t help but relish the cringeworthy moment when the murderer finally carries out the act. And while we cling to the edge of our seats for the detective to catch the perp, we can’t help but wonder “would it be so bad if he/she got away with it this time?” We love to hate the villain. This is a time-tested trope to us, but to Hitchcock’s audience, it was something more than a guilty pleasure. The silver screen changed the way people consumed entertainment. Where someone could cling to a book from the comfort of their home, their feelings hidden from all, hiding your perverse emotions is a little more difficult in a crowded theater. For example, do we laugh when Herb and Joe discuss the perfect murder in their suburban home? Who are we supposed to empathize with? It was frightening.
In the case of murder this is especially interesting. Robbery or blackmail may not be easy to go back on, but it is possible. Murder is the most permanent act imaginable. Madness, passion, downright psychopathy – these things are so powerful that they can convince someone to end the life of another is so strong within the human psyche, and we just can’t help but love it. Hitchcock knew this completely. And, I like to think, he laughed.

http://dreager1.com/2013/12/09/norman-bates-vs-luffy/