Faolyn
(she/her)
Slender Man is imaginary. These girls thought an imaginary being wanted them to do something. That imaginary being had an actual impact on their real life.OK?
What does this have to do with point that imaginary things don't actually cause real events? According to the Wikipedia entry you linked to, the cause of their actions was mental illness ("Weier and Geyser were both found not guilty by mental disease or defect and committed to mental health institutions"). I assume that you're not meaning to say that the fictional "Slender Man" caused those girls to do what they did?
And I also assume that you're not suggesting that RPGers have the sort of delusional relationship to imaginings that these girls did.
Just recently, I had a conversation with someone online who was terrified that Smile Dog was actually real. This person was an adult with children of her own. I had to spend quite a bit of time reassuring her that no, Smile Dog was just something that someone made by photoshopping a picture of a dog and that no, I never had to pass the picture around chain-letter style to avoid having it come and attack me.
Countless children modify their behavior to get presents from Santa. Countless children agonize over what body parts they can leave uncovered to avoid having the monster under the bed eat them (according to my mother, she thought it was OK to leave her feet uncovered; I, on the other hand, thought that feet had to be covered but my face could be uncovered).
People's beliefs cause them to act in certain ways, even if the thing they believe in doesn't actually exist.