Kafkonia
First Post
I'd be wary of being too specific about the details of the demiplane, because then somebody might get the bright idea of going there, and how do you run an adventure in the place where people go when they can't make it to the adventure?
I recall some discussion of similar situations in the World's Largest Dungeon thread (one DM had a wandering box-thing that would periodically show up and eat/disgorge a PC.) If you want something that will make sense in-character for them to keep around, you could always have it occasionally (very occasionally) invest the PC with some of the "potential energy" he didn't use while he was missing -- ie, an extra spell slot, an extra rage, extra turning, temporary hit points, etc.

I recall some discussion of similar situations in the World's Largest Dungeon thread (one DM had a wandering box-thing that would periodically show up and eat/disgorge a PC.) If you want something that will make sense in-character for them to keep around, you could always have it occasionally (very occasionally) invest the PC with some of the "potential energy" he didn't use while he was missing -- ie, an extra spell slot, an extra rage, extra turning, temporary hit points, etc.