Jack
Alternate reality, where Angels, Demons other monsters are very very real. We all got trapped here by one of the seal's on Lucifer's prison.
Even the TARDIS can't get out.
But, well, the seal takes us from our realities, from all sorts of different points in our timelines. What was the last thing you remember from home, anyway?
Oh, and then, it will send us right back to where we left, with no memory of being here. THen, sometimes it will bring us back again. Soemtimes with no memory of here, and other times the memories will come rushing back.
It's all rather quite fascinating. If it wasn't for the fact that there's been about three different versions of me, and I remember none of it.