Really everything that is not tangible or a law is a theory. An assumption. Something we can never know if it is correct or false.
You see where I'm going with this.
Slenderman's exsistance is just a theory. If you're like me, sitting here, reading this on your laptop/desktop and thinking back to all those ARGs. They claim it's real, But us, the humble veiwers who have yet to see the man, have no way of knowing. It's very plausible if it is real or fake, essentially Schrodinger's cat. A lot of things can be compared to that experiment, that theory, even you, dear reader, or me. You have no way of knowing if I exsist. I have no way of knowing you exsist. You, and maybe everyone on this wiki, could be multiple personalities of mine. I could a personality of yours, also. EMH and MH and TT and DH and MLA and EVERY SINGLE ARG could be real or fake.
We have assume they're both real and fake simultaneously.
You see where I'm going with this again.
Slenderman must be assumed real and fake simultaneously. AND the fact he cannot be harmed by any conventional means. He can and can't. There is no way of knowing until you metaphorically open the box and look at the cat. So, the only way to know what harms him, what he does WHY he does it...
Is to confront him. Get the answers. No one, to your knowledge has ever done this. To your Knoweldge, he may not even be real. But we cannot be sure. It's maddening to me espeially since I've dedicated my life to doing this, being sure, finding answers.
So who knows? He might be cool to have a chat with. Assuming he can talk...