First, I should note that this is a series that is right up the alley of people like Dergonu... it were a VN. This series, Under Jurisdiction by Susan R Matthews, mostly follows Andrej Koscuisko, a Drakonij Prince and would-be (though not by his own will) Inquisitor.
The Under Jurisdiction series is based in a sci-fi future where humanity, at some point, diversified so greatly that sub-specification has occurred (though most aren't quite separate species entirely. In this future, humanity (such as it is) is ruled by the judiciary, in the form of the Bench. All humans are subject to the law as proclaimed by the judicial forces, and punishments are mostly corporal... horribly so in some cases.
In this setting, torture is not only allowed, it is actually carried out by licensed medical professionals trained to inflict the maximum amount of pain to gain confessions of crimes (regardless of how heavy the evidence is), and, where it is justified, to torture them to death in the most horrible of fashions. This legal use of torture as a deterrent to criminals has led to a gradual decay in the morale of the planets ruled by the Judges on the Bench, and rebellions have begun to occur on a regular basis by the time the protagonist, Andrej, takes his first steps into the world of the Fleet.
Andrej is an extremely complex man... a man raised in a noble family of oligarchs who believe intensely and with absolute conviction in the duties of noblesse oblige and the duties to those under a lord's protection. He is also a young medical professional, a genius surgeon and chemist with a the kind of skill in actual surgical procedures that is seen so rarely as to be unheard of. He understands the human body (all races) to a degree that is often terrifying, and this is part of what becomes his plague... for when he begins his training, he discovers that, to his horror, the process of Inquisition brings out an intense, sick hunger to inflict pain upon and dominate the subjects that come under his hands. Coupled with his natural understanding of the body and human psychology, he comes out of his training as the most horrifyingly skilled Inquisitor in Bench history, an artist of pain eternally on the verge of madness due to the conflicting imperatives within him. He is only held back from the edge of the cliff by the efforts of his Bond Involuntaries, former criminals implanted with behavioral governors that force them to absolute obedience, so they can serve as his aides, and they are thus under his protection. Their care for him, for his sanity, for his health, and for his honor, is all that keeps the sadistic madness at bay as it fights with his honor and inherent compassion...
The story follows Andrej from his training as an Inquisitor and first encounter with a Bond Involuntary, to his first duty as a Fleet Inquisitor and beyond... His fight with madness as he tries to glean mercy and justice from the horrors he is forced to perform on others, his fight to keep his honor, to protect his Bond Involuntaries from others who would use them poorly, and his fight with his own, culturally-ingrained sense of filial duty are intense to read. For all the foreignness of his culture, Andrej's journeys through life leave behind an impact far out of proportion for the actual deeds he performs.
Unfortunately, if you have a weak stomach, I can't recommend this story at all. The galaxy Under Jurisdiction is one of the most horrifying dystopian sci-fi systems I've ever seen... all the worse when you realize that it all began out of a desire for justice and fair play in a universe where human racism has, if anything, gotten worse thousands of years after leaving Earth.