>>226296
>Isn't legally speaking an Inquisitor still beholden to the Ordo Lord and overall Lord Inquisitor of his sector?
No. Lord Inquisitors are #1 not appointed on a sector-by-sector basis, some of them do happen to claim a specific sector as their stomping grounds but this is totally unrelated to their rank and you don't have to be a Lord Inquisitor to do that (most people who do this are several ranks higher than Inquisitor Lords, being Inquisitorial Grandmasters, which implies that either there are lots of sectors with no sector-level coordination at all, that the inquisitorial org chart is absurdly top-heavy, or else that inquisitors have space marines outnumbered by at least an order of magnitude, not counting interrogators and acolytes), and #2 the rank confers no authority whatsoever, but rather serves as a formalization of authority they've already gained just through cultivating enough respect in their fellow inquisitors that they can rely on their suggestions being followed.
>Also, handing out daemon-infested Exitus rifles is certainly more than enough reason for any non-Xanthide who finds out about it to declare our theoretical Inquisitor Extremis Diabolus.
That is what I just said, yes. And the accused inquisitor can go ahead and declare the accusing inquisitor Extremis Diabolus right back, because both of them have the exact same legal authority over the other and do not have to justify their actions to anyone. And given that Xanthites exist at all it is obviously true that blatantly heretical inquisitors not only exist, but exist in sufficient numbers to form their own sect. The Inquisition can be used to justify basically any plot development the GM wants.
>>226626
>No, it's highly dependent on the sector.
Not really, no. While specific inquisitors might bind themselves to a hierarchy, and those specific inquisitors might be concentrated in a specific sector, if a new inquisitor enters the sector he is not under any obligation to join up with the existing inquisitorial hierarchy, nor to even notify the others of their existence. If one of the inquisitors who is nominally part of a sector-level hierarchy decides to leave the hierarchy, there's nothing they can really do about it.
>>226668
That would be the prologue to the All Guardsmen Dark Heresy campaign. Also: Do not ever introduce people to the 40k universe this way. This is the kind of campaign you serve up to people who know what to expect. It's not the kind of thing you smack someone across the face with when they don't know what they're getting into.