Nero was meticulous, and would not make a silly mistake such as leaving Unity's Network out and about in his room for others to find. In fact, he made sure to purify his room regularly, removing even the smell of the ingredients he used in his card crafting, though the ingredients themselves remained in the room. Still, that was not nearly enough to give any hint of what he was working on.
Thus, there was nothing in the room that could, in any way, incriminate him of anything. Yet when he opened the door and found his mother sitting on the far end of the room, looking over the ingredient he had stashed, he felt like he had done something incredibly wrong.
There was no way to explain this - it was just a gut feeling. Her perfectly normal smile looked incredibly menacing to him, and that pleased expression she wore was to him a forbidding omen.
