No, not really scary guys who fix cars for Dracula but the "hows" and "whys" of the horror world. And I also don't mean that persnickety shit where know-it-alls ruin everyone's fun by complaining about something being physically impossible in a supernatural story, like a vampire not reflecting in a mirror, which is, yes, impossible because the reason you can see the vampire is because lights reflects off of him and if your eyes can see that reflected light so can a mirror. But, you know, it's a vampire and the mirror reflects the soul and we all get that when watching Dracula.
I'm talking about the actual mechanics of how something works within the logic of the story itself. Let's take a look at three horror staples and ask a question of each in the hopes of understanding their inner workings a little better.
For starters, how does a vampire suck out the blood? Seriously. Usually, when we see the results of a vampire attack, it is as pictured above. A couple of bite marks and some drops of blood. But does that mean the vampire is sucking it out through his teeth? Because, if not, the neck should be a lot messier. If the vampire is biting into the neck, to get the blood flowing, and then sticking his mouth over the gushing to lap it down, there should be blood smears all over the neck or, at the very least, a big-ass hickey where the sucking took place. Personally, I think vampires have fangs that act as straws. Much like a snake has ducts that spew venom, the vampire has ducts, either within the teeth themselves or just above them, that suck the blood out neatly and cleanly. It would seem the wisest evolutionary move for an animal reliant upon such feeding to waste as little blood as possible.
Now let's consider the werewolf. The werewolf is a person who, with the full moon, suffers a full DNA reworking and becomes a hybrid wolf/human. The werewolf then goes out and starts attacking. Why? Animals attack for two reasons: hunger and fear. Take a lion. It attacks prey when it is hungry and intends to eat it. It attacks a human wandering into its territory when it feels threatened. It never attacks because it's bored and feels like attacking before taking a nap. So a werewolf is attacking for one of those two reasons. Now, when a person knows they are a werewolf, they will often go to great lengths to keep themselves from being set loose so as to stop their murdering rampage. They will lock themselves up or ask someone else to in order to prevent the unthinkable. But might not a better plan be to stuff yourself silly before the transformation?
Let's say you know you're going to transform at midnight. Okay, buy a large roast, cook it up with some potatoes, eat the whole thing and maybe have an entire pie for dessert. Eat until you can, literally, put not one more morsel in your mouth. When you transform you will be sated and, perhaps, even a little sleepy. Hey, that's another idea! The night before the full moon, don't go to sleep. Stay up all night and then, the next evening, after you've been awake for 36 hours, eat that enormous feast of food and guess what? When the transformation happens you'll do what any other wild animal does in the same circumstances (or, for that matter, my cat): You'll roll on your back, pass out and snore like a gas-powered chainsaw running on a ten-gallon tank. You're not hungry and you're not afraid. Threat diffused.
Okay, now over to zombies. I assume they can smell a living human just a predator can smell its prey. This is why I don't think the scene in Shaun of the Dead would work, again, within the logic of the genre itself, where Shaun and the rest pretend to be zombies to get past the real zombies. I mean, if that works then it means zombies are literally just going by visual cues in which case, surely they would go after each other by mistake every now and then.
But maybe that's wrong. In 28 Days Later, the zombies don't detect Jim (Cillian Murphy) in the church until he speaks. If it all went by smell it seems like they would have detected him earlier. But those zombies are more about rage anyway, not so much eating. And zombies have been approached by so many different angles now, without a real primary source to sort out the rules. We've got plenty of old zombie movies as well as the one that gave us the modern zombie, Night of the Living Dead, but there is no original source novel, written in the late nineteenth century, that serves as a guide for the development of all future zombie tales. It really is an open-source kind of sub-genre, which probably accounts for the haphazard inundation of zombie material these last several years.
There are many other horror staples that may have multiple "hows" and "whys" attached to each and it's an interesting way to think about each sub-genre more deeply, looking for answers that help us understand the nature of the beast just a little bit more. And now, if you'll excuse me, I have to go eat a massive meal and pass out in front of a movie. What's that? Werewolf? Nope, just a slob.