The Once-ler glanced up when Lingormr entered, and gave the other man a slight nod before continuing to draw, half-listening to the conversation. From the sound of it, Lingormr believed Soma meant to stay in her room for the night, and that the young woman had no intention to otherwise enlighten him. Which was probably for the best, he reasoned. The former businessman had brought up both the idea of visiting Rapunzel and that the stuck book would only be accessible at night, and Soma would have likely stayed in had he not mentioned either.

As for why he himself was here? Copying her map was a valid explanation. If Soma didn't plan on telling Lingormr what she actually meant to do, the Once-ler would not let on that he was involved in anything besides getting himself a map of the institute.