Let me tell you about my character. In James Jacobs's "Sands of the Scorpion God" campaign, I play a catfolk ranger/rogue who dual-wields sickles. His name is Pr'ral. He helped his fellow adventurers infiltrate a subterranean city run by evil cultists of Rovagug, but we got captured when a badass umbral dragon left us all blind and weakened and pretty much helpless. We were placed in a gladiatorial arena and forced to fight giant-riding morlocks and other terrible foes. In the final round of the arena fight, we were pitted against a powerful glabrezu demon named Bezilak. And he mopped the floor with us.
With my allies unconscious and bleeding out or fleeing, Pr'ral was the only one who could save them. So I made a deal with the demon. Communicating telepathically, we came to an agreement, and in so doing, I saved my companions from certain death before a cheering crowd. But the cost was high.
My alignment shifted from chaotic neutral to chaotic evil, and Bezilak and I now have a much more intimate relationship. The specific details of the arrangement haven't been revealed to anyone but James and I, so I won't go into them here, but needless to say, Pr'ral is a very different character now that he saved his friends. He now cares only for himself, and will (and has) abandoned his fellows in their times of need if it serves him. He's also started taking levels in assassin. And when he needs things that he can't find (like a ring of invisibility that would have otherwise been unavailable in Sothis at the time) Bezilak has come to his aid.
While Pr'ral isn't quite intelligent enough to recognize the error of his ways, I do not lack such insight into the machinations of demonkind, and every session has been stressful, as I await Bezilak's next appearance and the inevitable calling in of what Pr'ral owes him. So imagine my surprise and—I'll be honest—horror, when I was editing Pathfinder Campaign Setting: Demons Revisited, and I came across a familiar character as the sample glabrezu. Yeah, it was Bezilak. I was then forced to read (in the process of editing) the deep, dark truth of how vile a creature and sinister a manipulator he truly was. I think it was James's own demonic means of torturing me. He certainly got a good laugh out of it when he found out that I was doing an editing pass on the book.
Game Masters looking to add that same sort of terror to their demon-filled games will find plenty of additional inspiration in Demons Revisited, including a number of influential members of each demonic race that NPCs can summon or who can be archvillains themselves in myriad campaigns. Further, each of the 10 demons presented in the book also features a variant of the half-demon template specifically designed to reflect the abilities and flavor of the specific demonic races. Demons are unpredictable, wholly evil, and unfathomably twisted creatures, and Pathfinder Camapaign Setting: Demons Revisited captures the raw madness like no book before it.