I’ve been running some adventures in the Five Peaks in my current campaign, ever since a PC decided to play Ruinil Alam, the disinherited nephew of Carilon Alam, Duke of Alamie. He and the other PC’s journeyed to the Gorge to meet with the Eyeless One after befriending Sir Edmund, the Knight of the Red Tower, at a tourney in Tuornen (the EO’s knight errant lieutenant in the civilized realms, though few realize the connection).
I had the Eyeless One being a half-fiend sorcerer/thaumaturge of great power (I adapted the thaumaturge for arcane casters using planar binding instead of planar ally). He was called the Eyeless One because he never revealed his face, not because he’s actually eyeless [though another idea I had was that he was naturally blind/eyeless, either from birth or as the result of becoming awnshegh; in this case I would have given him Blindsense as a racial trait].
The Eyeless One is THE source regent of the Five Peaks IMC; there are no landed regents, except for the occasional blooded tribal leader who tries to “unite the tribes.” This rarely lasts more than a few months or years before the would-be leader is toppled and happy chaos reigns again (which is generally how the tribes like it, as they value their freedom above all else).
The Eyeless One is feared, hated, and sometimes sought out (at the seeker’s own peril) by the FP’s residents. His knight is known there as his direct representative, and thus is given a degree of respect and safe passage by most of the tribes.
IMC, the PC’s bargained with the Eyeless One. They gave him lots of money (50 GB) and 1 permanent point of bloodline each (via a small ritual); in return, he would use his influence to have Sir Edmund lead an army of humanoid mercenaries, supplemented by potent summoned units (the EO was at least a 12th level caster at this point). These armies would march south to ravage Alamie, even while Alamie was marching with its main force to attack Tuornen.
The EO kept his word, and did as he promised. Sir Edmund warned the PC’s that these were humanoids, and they expected to raid and loot in addition to their pay. Ruinil accepted this as a necessary evil. He’s been eating that ever since.
Tuornen and Alamie met in battle, and it was fierce, with over 20 companies in each army. Alamie won a Pyhrric victory - they took the field, but at high cost. And that same night, while the Alamiens were nursing their wounds, the Five Peaks army struck, the goblin wolfriders overrunning the Alamien sentries, throwing torches on the tents, and generally sowing chaos and confusion before the main force of trolls, giants, goblin infantry and archers, and gnolls stormed into the camp and proceeded to slaughter every last Alamien they could get their hands on.
As it turned out, Ruinil himself had been captured in the battle, and he was freed by the goblins and escorted to safety by Sir Edmund (who does have a shred of honor despite being a rather wicked fellow at heart). And then was able to ride down and duel a fleeing Carilon Alam, and in that duel finally have his vengeance (Ruinil’s father was Carilon’s older brother, who was murdered along with his wife when Ruinil was still young to remove any potential rivals for the duchey; Ruinil was hustled off to Tuornen by their loyal servant, and raised there in Laela’s court).
So in the end, Ruinil got his duchey, but it was in a sad state. The humanoids spent a good season raiding an pillaging most of Alamie. All but the 2 southernmost provinces were pillaged (dropped 1 level), as were all the law, temple, and guild holdings (these were wiped out entirely). Even the capital castle, only weakly garrisoned, was stormed and sacked.
So in the end, the humanoids got away with a LOT of loot, Alamie was badly damaged but a nice clean slate for reconstruction by a new regent, and the Eyeless One proceeded to rule up the sources of northern Alamie 
. And he dropped a stern warning to Ruinil that he should leave the northern provinces in their rural conditions, or Alamie would suffer for it. Nice guy, the Eyeless One!
So Ruinil basically hates his guts, would love to remove him, but fears him - which is as it should be, IMO. He owes the gaining of his duchey to the humanoids, but hates the price that was paid by all of Alamie, and the guilt still weighs on him. Perhaps unsurpisingly, he also nurtures an intense hatred for the Five Peaks tribes, and would love to see them wiped out too. But he can’t deal with them until he deals with the Eyeless One, and seems none too anxious to try that out anytime soon. 
So there’s one story of the Five Peaks and the Eyeless One. More recently the group went to visit the dragon Lifesbane, whom I made a female for certain story purposes, but that’s a whole other story for another time. Until then.
Osprey