As stated on the main page, the various stories of the Holders begin with going to any mental institution or halfway house. However, when a Seeker goes into said institution and asks for a Holder, they are taken to a place that seems to involve Alien Geometries. It's quite possible that in the world of the Holders, the institutions are somehow connected through gateways to a massive institution that is housed in an alternate dimension, reconfigurating itself so that the Seeker can find the Holder they are looking for.