I always liked the insane Warhammer 40k setting. Sure, it’s dystopic and inhuman and the good guys are barely better than the bad guys (by our present standards), but at least there are bad and good guys that are easily identifiable.
It’s an universe of extremes, and compared to everyday reality, even a world of such extremes can be a satisfying escape. It might be grim and unrelenting, but at least it’s all clear-cut. At least that’s the case for most Warhammer fiction. Eisenhorn is a bit different in that respect.
In our reality, reasoning and understanding are excellent tools to better tackle the world around us, in the W40k setting they often are a path to death and damnation, but without them there’s no way that mankind could survive. And so, every Inquisitor lives on the edge, trying to learn enough to fight the enemies of the human empire, but also trying not to learn anything that could corrupt them and make them into the things they fight all along.
And Inquisitor Gregor Eisenhorn is walking on that edge. Abnett shows with great care the slow character change of Eisenhorn from a dogmatic into an open-minded Inquisitor, who always has to ask himself, what ends justify what means, what price is he willing to pay?