[quote=@SimplyJohn]
<Snipped quote by mattmanganon>
If she doesn't trust the captain, why did she just hand the note over to a random Space Marine on the steps of the cathedral without confirming his identity first? Her cover identity has now been compromised, rather than simply presenting herself as a Commissar until such time as she could gain a private audience to reveal herself properly.

The Inquisition holds no sway over the Adeptus Astartes, they they completely separate organisation who cooperate due to ancient pacts of support given at the time of the First Founding. A High Lord Inquisitor would have no additional authority to give orders to a Lamenter compared to a Lord Inquisitor.

The note is addressed to 'Commander at Hive City Acane', which would mean either the commander of the local PDF or the civilian governor, depending on the local hierarchy, but has no bearing on the Space Marines. She appears to be trying to use a specific order as a carte blanche to requisition any assistance she can, something which as a Lord Inquisitor she could do anyway.

Why would the Space Marines accept a note without any form of identification instead of a far more secure electro-tattoo? It's possible this piece of parchment is either a forgery or that it's been taken from the original owner. Verification of the document would be required before it could be of any use, and that would take time, communication with the office of High Lord Inquisitor Fyodor Karamazov and would increase tensions between Marian and the Marines which could've been avoided had she simply introduced herself as a Commissar.

If she'd just flashed her tattoo and said "Inquisition business" the Marine would've simply accepted her authority until such time as she proved a threat to the sanctity of the Chapter, with no further explanation of her actions required.
[/quote]

I really should have mentioned that the letter to the space marine on the steps didn't have any mention to the fact that she was an inquisitor. As far as that guy is concerned, she's just on a mission from the Officio Perfectus. So, if he blabs, then he's just telling the enemy lies, which is of no harm to her mission. I thought that was implied, being that, as you said "Why would she reveal it to only the captain and a grunt?"

Because if she flashed her tattoo here, then everyone would know. And as stated earlier, the less people that know that the Inquisition has interest in this . Instead, a letter with the unfakable seal of the Ordo Hereticus on it is good enough for now. I was thinking that she flashed it later, as he would, of course, want to question her in private. As for the guard, the same, only with the Officio Perfectus. That is a seal that cannot be faked. The only way to get it would have to get it straight from the head office on Holy Mother Terra, a place which Chaos cannot touch.

Also, Space Marines respect the chain of command, when a letter comes from Holy Mother Terra, they tend to not question it. If there is one thing you need to learn is that Humanity is kinda stupid... Just, as a rule in 40k. I mean, their whole system is based on the ideology that "To question your orders is to know doubt. To know doubt is heresy, which is punishable by instant execution."