One of numerous articles that appeared in the popular press following the stabbing by two girls of a third in Wisconsin, related to the fictional character Slenderman.
This article relates a bit of history about how the character was invented and popularized on the website creepypasta. It seems the two girls who committed the stabbing of a friend may have actually believed that Slenderman was real and that they were going to be able to live with him, once they killed the third girl, who was a friend or acquaintance of theirs.
At least one of the two girls is now deemed unable to stand trial due to her mental state. What this might mean is that she is delusional or psychotic in a clinical sense.
The article quotes Joanne Cantor, PhD, a national expert on children and the horror genre in media. As Dr. Cantor aptly points out, even non psychotic kids can believe fictional representations on the media, and so parents need to work to clarify to kids what’s real and what’s fictional.
The problem here is that kids now live as much on the media as in the world of waking reality. So it should not surprise us that kids can get confused. Whereas only about 1% of Americans suffer from schizophrenia, which is the most common illness implicated in delusions and psychosis, many, many suffer from anxiety conditions, that is less severe emotional problems during which the child or adolescent knows that fiction is not real but often feel it is.
Further, since kids up to age 8 and even beyond lack the cognitive capacities to firmly discern what is real and what fictional, the problems can be profound and highly troubling.