A program used to monitor and detect the operation of the virtual world—that was Nolan's true identity.
Hao Ren found a vast amount of information about the construction of the virtual world on the equipment in the cavern, including a section that happened to mention Nolan. If a sudden flash of inspiration hadn't prompted him to investigate these things, no one would probably ever have known that Nolan's true form was like this.
The Zhuom people and the Eldest Son had worked together to build a massive virtual system that could simulate the real world almost perfectly. The system consisted of two parts: the Eldest Son's biological will and the AI within the mechanical equipment. The Eldest Son's biological will was the main body of the virtual world. In truth, the entire system had been built within this ancient creature's dream, and the Eldest Son's immense mental power could accommodate billions of humans living in the same dream. The mechanical AI, meanwhile, was more like an attachment used to maintain the system. It existed within the countless machines connected to the Eldest Son, including the alloy cylinders Hao Ren had seen before and the many array servers deeper inside the shelter. They constantly monitored the operation of the virtual world, serving as the sentries and babysitters the Zhuom people had left behind in the real world after they fell asleep.
As the mechanical AI of the monitoring system, it was extremely complex. Nolan was merely one of the interfaces through which those monitoring programs manifested.
However, she knew nothing about her own identity, because her self-perception had been altered in the earliest configuration. She simply lived in this virtual world, experiencing everything within it as a human would. All her perceptions were converted from simulated signals into a human perspective.