"Well," Luna said, her expression thoughtful. "I have noticed the saturation of my sister's magics throughout Equestria since my return. She has woven power from the elements into the very fabrics of the ecosystems and societies. It is subtle work, but its effects are profound. Perhaps that is why you see little of the shadow. As for why it is here, perhaps it is fear from the past? We spent the better part of several millennia fighting the shadow. We… we lost much. It would be a part of her."