So in theory and practice who is more powerful a Commissar or an Inquisitor? Also, would it be feasible to have a commissar work for us?
The more discipline we have with the military the better.
... You're joking, right? A Commissar's purview is simply with the Imperial Guard, maintaining morale throughout the regiment(s) and ensuring that the political objectives of the Imperium are fulfilled to the highest efficiency.
An Inquisitor is an entirely different breed. Not only do they have the authority to commandeer entire regiments of the Imperial Guard and shoot anyone who dares speak up about it, they have ABSOLUTE POWER at the planetary level -- you simply
do not make an Inquisitor angry, because he can literally execute the governor of an entire world if he deems him irrelevant or disadvantageous to the Imperium's goals in any way. They can cut through all the red tape with the brutal efficiency of a chainsword, and no one -- NO ONE -- outside an Inquisitor's own organization or the High Lords of Terra themselves have the power to rein him in. They even have a substantial amount of pull with the Space Marines, as evidenced by the fact that Inquisitor Gwydion Llane here, being of the Ordo Xenos, can call in the Deathwatch. These guys are the very best Space Marines the Imperium has, with an average of only one out of a hundred warriors from each Space Marine chapter in existence (except Grey Knights) considered good enough to join their ranks. When you want something dead, so dead that the word 'dead' makes it sound like they went to f***ing Disneyworld, you bring in the Deathwatch. Because they
get the job DONE.Lord Inquisitors are even scarier. Yeah, that Cornellius guy who got us into the big
I in the first place? He has
multi-system authority, meaning he can sentence entire swathes of worlds to Exterminatus. It's been done before. A jolly old chap by the name of Lord Inquisitor Kryptman unilaterally deathstarred dozens of Imperial worlds at one point in time.
How do you rein these guys in, you ask? Well, their own organization acts as judges for the evaluation of Inquisitorial agents. Should an Inquisitor's conduct be found lacking or more damaging to the Imperium than it's worth, they can be censured -- recalled to capital to face charges before the Inquisition's own council. This happened to Inquisitor Gregor Eisenhorn before, when he destroyed a particular pair of Xeno artifacts, but they voted to keep him around regardless. You don't get trials to prove your innocence, because there's no such thing. The only thing the Inquisition cares about is how useful you are. As long as you prove to be more of an asset than a liability, they keep you around.
Essentially, not much can touch an Inquisitor. They literally wield absolute power over all elements of government at the planetary level, and have access to ALL the troops and resources at the Imperium's disposal, including the
Astartes. And the only ones they really have as peers are their own Inquisitors and Space Marine Chapter Masters. Of course, this doesn't stop people from trying to kill us out of spite and contempt for sticking our nose into their business, so it's also important to strike a balance between throwing our weight around and keeping low-key.