Perhaps children with a reservoir of psychic power draw spirits and the like as an oasis of fresh water draws someone parched of thirst, for reasons beyond what we might understand. To increase their own power, to break beyond the bounds of what parapsychological limitations their classification might have placed upon them. (You know, geographical borders and whatnot.)

Perhaps they can use that power to barter in, I don't know, diabolical bazaars, far removed from this plane of reality. :)