Maris is a thief. A common, low down, swarmy thief. It’s not her fault she’s that way, though. She’s nice, has a sweet personality, and is most likely to talk a person into giving ‘the poor, suffering little me’ their money, due to her limited skills as a pickpoket.
What she is skilled at, however, is very, very strange for a theif. She likes reading, and has collected many old manuscripts, and is sometimes saught out for just knowledge.
The local band of 'nasties' (goblins / orcs / whatever) lives in relative peace with the local population.
Along come the PCs and go through their usual heroic monster bashing routine, wiping out the nasties and pinching all their stuff, then continue on their way.
Problem is, they don't kill ALL he nasties. The survivors want revenge and, after spending a few months recovering, start to take it in their own inimitable style (which is not unlike that of the PCs come to think of it).
Next time the PCs are in the area they find themselves VERY unpopular with the townsfolk.