Nightling appears in Telepath RPG Chapter 2.
If the Hero have enough personality and decides to talk to Nightling while Grotius is in the roster, Grotius will become Nightling's friend after some convincing, and Grotius will give the Hero his Blue Orb.
"It's a history book. It's about how the shadowlings and spriggats started fighting each other. It's pretty interesting."
"Um, right. How about you go away now."
The Hero may call Nightling "Gloomy McGloomyPants".