Watching this now
I'm only 15 minuets in but its very interesting. I've seen some people say, not on here but on articles, that the girls shouldn't have been reading stories like that at their age but don't we all?
I remember being their age, sitting at the back of the bus on the way home from a school trip ice skating and myself, a friend and some classmates were telling creepy stories to each other. I remember one was about hiding under the bed covers and hearing the sounds of a killer doll coming up the stairs. I've also, from around the same age, always been interested in urban legends.
I believe it's not just the content or age at which you read them but there has to be something seriously wrong mentally for you to do what they did and believe something like the slenderman is real.
It's immortality, my darlings