"You're... not frightened of my new appearance?
Nia *is* actually a bit freaked out by Gegren's appearance, but is trying to keep a lid on it as she remembers a former comrade (Grillo) who was disfigured by acid who did not get Nia's full support. She has vowed to do better this time. So long as Gegren is acting as he has been, she can be good with his new, hellish appearance.
"It was like something underground burst free, leaving a cave or something."
Torin's statement gets Nia's attention. A cave below the mysterious light? She's in. Nia will size up Torin. If she gets the sense that he will freak out at the sight of trouble, she will leave the half-elf here. If he seems particularly capable, she will ask if he wants to be a guide to the cave - but she will make clear that she will likely be entering said cave.