Talking to Blup gives quest to enter the caverns of chaos
Blup is one of the NPCs that gives you the quest to enter the caverns of chaos. However, he doesn't have any dialog relating to this, which makes this rather weird.
Yes, I noticed that too. And more generally, the elder and the druiid don't have related dialog until after you finish their quests.
Easily solved by giving all NPCs a little more dialog hinting that the monsters "...come from the west". Even Blup, who is too scared to go looking for his mommy alone.