Technically speaking, it's a place outside of all known universes, but that's just splitting hairs. Time should be stopped where you come from.

[Barring exceptions like people who come from different points in time in the same universe, but as far as Skulduggery's aware, everyone gets returned to the point they were taken from. Metaphysicists might be able to explain why, but he sure can't.]

Everyone is somebody important. Xion's one of the other Foreigners here. I think she might come from your world.