The Pacific Rim coalition is one of the New Earth Governments of the Cosmic Era
Gartheia - the flower-pot Island
To the first or casual observer, this island sitting out in the ocean seems normal, if not heavily covered with lush trees and foliage. To those who have extensive nautical experience know something is amiss, especially since the island is never in the same place twice.
At this time an old man, one who told the Prince wondrous tales during his childhood, walked upon the bridge and witnessed the prince commit suicide, saw him fall into the water. “This is the Bridge of Fates. I foresee great sorrow and happiness. This bridge shall never remain neutral, shall know tears of joy and the blood of innocents”.
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.