A former adventurer who lost his nerve but not his greed. He sneaks into lairs, scribbles a map of the gold piles and exit routes, and then sells them to "braver" souls for 10% of the haul.
She never speaks (to avoid being heard by the dragon). She communicates solely through her incredibly detailed, charcoal-smudged maps that include notes like "Watch out for the loose gold coin—it squeaks." Sees what the dragon hoards, draws the maps NPC...
The NPC is actually a transformed dragon or a mimic who lures greedy adventurers into the lair to provide the "hoard" with fresh gear (and the dragon with a snack). A former adventurer who lost his nerve but not his greed