In fact, Miss Teresa didn't know what the "Child of the Invisible" was either. When the group was resting, the ground suddenly shook as if something had emerged from the underground. Subsequently, they were attacked by invisible enemies. Since there were too many enemies surrounding the camp at the time, Miss Violet led them to temporarily retreat.
But Miss Violet, after all, was a Thirteenth Rank Witch. After temporarily escaping the enemy's encirclement, she quickly detected the "nest" of these creatures. Therefore, she went with her personal maid to deal with the source of the "Child of the Invisible," while Miss Teresa and the other five maids blocked the pursuing enemies here to avoid direct contact with the truth of this attack.
"Over there."
Though she had only interacted with Shard for about an hour in total, the bespectacled witch still immediately discerned Shard's current thoughts: