To Eviscerate: Slaughter and the Cannibal Movie Slasher / Butcher / Ripper genre

Other animals give us clues to our own animal behavior, both that behavior in normal times, and in unusual times. 

During stressed times, animals kill their own kind, and will eat them. Recently, the Asiatic Lions of India, with a population of about 250, killed each other. 125 were slaughtered or half the population.

In normal times, the rare Asiatic and African lion eats meat just as needed. They appear so calm if plenty of meat has been available. They laze around sleeping for days in the shade away from the heat.  During those times, they fight less, and mame and kill both less other animals and their own (males upon younger males, females ganging up on rampant cruel males).

But, it is their nature, as meat eaters to eat meat. That takes killing with stalking, attack skills and methods of causing quick deaths (chomp to neck, follow the blood scent and trail to the partially ex-sanguinated (the deer bleeds out), deer a few hundred feet to their death spot).  Eviscerate. Eat. 

There is among particularly animal groups:

1. revenge killing

2. pecking order killing

3. unneeded killing of others from their societal stresses, of their kind or other species
   

4. mass killing of other species monumentally beyond any food or hunger need (wolves killing hundreds of buffalo at a time in a frenzy)
   

5. gang killing of another gang: wolves do this in Yellowstone Park

6. Males killing females, females killing males, both killing babies

7. Shark feeding frenzy, where all including their own may be eaten. The same applies to species of fish, including piranhas.  

8. wanton killing, random or planned of  "lessers", who are lessers for one reason or another. Cat's play with mice caught, Jack the Ripper kills prostitutes. The Cartels kill each other, sometimes just as Messages of prowess / warnings. 

Wow, of killers, that's a lot of reasons to kill, and lots of victims killed.

What the Dark Disordered share with these animals is, really, ALL of those traits.

This is what that ex-sanguinating and eviscerating does this:

synonyms for devitalize

• deaden
• debilitate
• desiccate
• destroy
• disembowel
• emasculate
• enervate
• eviscerate
• exenterate
• weaken

What does it mean to eviscerate someone?

1a : to take out the entrails of : disembowel. b : to deprive of vital content or force. 2 : to remove an organ from (a patient) or the contents of (an organ) intransitive verb.  

(from Merriam-Webster, online).

Eviscerate

e·vis·cer·ate
/əˈvisəˌrāt/
Learn to pronounce
verbformal
past tense: eviscerated; past participle: eviscerated

    disembowel (a person or animal).
    "the goat had been skinned and neatly eviscerated"
    h
    Similar:
    disembowel

gut
remove the innards from
draw
dress
embowel
disbowel
exenterate
gralloch
paunch

    deprive (something) of its essential cont
    "myriad little concessions that would eviscerate the project"

(from Google Oxford, online)

These are the traits also of the movie genre presented here: Butchers / rippers.