Does anyone know the origins of the Slenderman Mansion?
I'm currently putting together a mini docu-series covering the history of Slenderman and the impact it's had online. At some point in 2013 (Maybe 2012?) people began coming up with the idea of a Slenderman Mansion where all the creepypastas began living together. I can find tons of fanfics discussing this between 2014 - present. But I can't locate where the original idea came from.
That honestly seems like something maybe one fanfic brought up as a small thing, and then the community just sort of snowballed it from there into a variety of projects. I'm not sure you'd be able to find the original author unless you specifically combed through every Mansion page or website and checked the dates to see which is the oldest.
I'd maybe look up when creepypasta OCs started becoming a thing. I estimate its anywhere between the inception of Marble Hornets/TribeTwelve and Jeff the Killer, most likely after the fact, when there was a large enough collective to be considered available for this mashup mansion thing.