Nikka, you say

Killing (in real life) in itself is not erotic at all.
I don't agree. While I never have killed anyone or anything for or with pleasure, There are those who do derive significant pleasure form the act. Read the book "Hunting Humans" for a look inside the sociopathic mind of a serial killer. For some of our predatory fellow beings, the pleasure is not just in the hunt ... There is also an escalation in behaviour exemplifed by these "rogue" beings.

The animal kingdom has many examples of an animal killing for pleasure, especially a domestic animal. My dog has killed birds, for example. There is no way he did it for food; it was an instinctive reaction on his part (although wild kingdom in your living room is a little much to behold)

Erotic is in the mind of the beholder, and there is nothing more frightening than the human mind ...