The suspects believed that "Slender," as Weier called him, lived in a mansion in the Nicolet National Forest in Wisconsin. The plan was to kill the victim and walk to Slender's mansion and become one of his proxies, according to the criminal complaint.
The victim remains in serious but stable condition while the two girls accused of trying to kill her face charges of attempted first-degree intentional homicide.
Slenderman: The Internet-Age Boogeyman Folklorist Gail de Vos, in her book "What Happens Next? Contemporary Urban Legends and Popular Culture," explains Slenderman's origin: "Recognized as a fictional contemporary urban legend, created by Victor Surge on the Something Awful forums on June 8, 2009, Slender Man has gained prominence beyond the confines of the online forums. He is most often portrayed as a malevolent entity abducting and psychologically traumatizing people after stalking them for a long while."
The character is wildly popular among online fans, as researcher Sharon Hill of Doubtful News.com noted in an article in the February 2013 "Fortean Times" magazine: Slenderman "currently stars in an array of videos, YouTube series, alternate reality games, fan art, online horror stories and parodies.... Slenderman is an evolving meme." (Yes, there's even Slenderman porn, and no I'm not going to describe it.) It is a character in some ways similar to La Llorona, the wailing woman said to haunt ditches and rivers searching for children to abduct.