Would Nostramo really have been that difficult a world to pay visit to?
While there probably wouldn't be much difficulty in going to Nostramo I don't think that would equate to the culture of the Legion. The Night Lord's aren't based on Nostramin culture, they're based on Nostramin criminal culture and while there is overlap those aren't the same. I think getting an outside observer into the criminal underworld of Nostramo would be more difficult that accessing the culture of many worlds. Though you do bring up a good point about the secrecy of the Dark Angels.
Also, though not intentionally isolated Nostramo does seem to lack a certain level of Imperial oversight, considering the speed of its backwards slide. That suggests to me that Imperial personnel wouldn't be very common or super welcome, again raising the difficulty of infiltrating the Legion.
Taking that one level further, the Imperium had a whole ORDER dedicated to doing pretty much that with the Legions themselves. They were actually recording any name, interaction, custom, etc., they could for posterity. That would have been a gold mine for the Alpha Legion, even if only as a starting point.
Good point on the Remembrancer Order, can't believe that slipped my mind. Of course the use of the Remembrancers was largely voluntary and many Legions seem to have not had many, and many more of those that did carefully restricted access and heavily monitored them. Given that Night Lord ships sometimes lack the ability to illuminate the interior and they are notoriously unfriendly I doubt that there were many Remembrancers attached to the 8th.
Originally Posted by MontytheMighty
I just had a thought. What if that traitor Raven Guard is actually an AL posing as a turncoat Raven Guard? Traitor RG is his cover. I mean, it might be easier to get in that way than to impersonate a NL. At least this way, he won't have to worry that much about conforming to NL customs and all.
DUN DUN DUN
Interesting, but I'd call it unlikely. Firstly, the Raven is full blown missing his tongue, something that would cut down on the usefulness of an operative. Secondly, that's a really, really risky way to infiltrate any Legion, especially the Night Lords. Notorious cruelty and paranoia do not make for a group welcoming to outsiders, let alone to defecting enemies. A situation like the Raven's ends up in the skinning pits nine times out of ten if you ask me and I don't think the Alpha Legion would be willing to waste nine marines just to get one mute guy inside. Surely infiltrating the Legion conventionally would have lower risks, even in a difficult Legion to infiltrate.