Usually supplies are built to keep a person standing upright, however today PD has actually determined he desires Mei Mara to remain on her knees. More than that, he wants the placement to be as uncomfortable as feasible. Maintaining her head shifted the way it is allows her see just enough of the area to know how much difficulty she remains in. That viewpoint is not any kind of advantage. It just shows her that she has excellent reasons to be very afraid.
