Your addition is actually completely antithetical to my message. It is literally the opposite of what I am conveying.
Stop telling people to encourage the cop inside their head.
How you treat fictional characters, given they are entirely objects of fiction, does NOT necessarily speak to your own character, and you do not need to be "careful".
It is not dangerous to imagine dark things happening to fictional characters. It does not mean you are secretly a bad person. It does not mean you unconsciously want to hurt people in real life. It is not a "slippery slope" to doing bad things to people in real life. You cannot damage your brain or turn yourself into a bad person by consuming "dark" fanfic.
I can write tentacle noncon of my favorite character all day long and be a fierce anti-sexual assault advocate in real life because what I do in my head is not the same thing as what I do in real life.