Bearing a Warrant of Trade is a great priviledge, and it might gain them armies, the aide of the Navy, or even the right to be a legitimate pirate. So, I have read some places that a small few Rogue Traders have made beneficial "alliances" with various Space Marine Chapters. I believe some even have a small designation on the Warrant that testifies as much. What might one have to do to gain such a boon from such rare, powerful individuals (from the RT's perspective) as this? I can see getting the Peer and Good Rep (specific Chapter) Talents, or maybe even Oath Bonded to the Angels of Death Talent, if they are incredibly lucky, and it carries over to RT, but I'm not really sure what "regular people", even ones as high and mighty as Rogue Traders, are likely to have done to earn the comaraderie, of a sort, of such men.
Once one gets past that, what benefits might they bring? Space Marines are great, but I don't expect to carry a unit of them on my ship, just in case, and they'd kind of make my other buddies useless. Their gear is mighty, but most is SM only, meaning they don't get the RT any closer to the good stuff, and that's never the problem for Rogue Traders, anyway.
All of this is mostly because, in my fiction, and possibly for players who might inherit aspects of it they don't change (the Warrant has lived a lot longer than them), there is a small bit of stuff at the bottom that says that the Raven Guard will come to the Dynasty's aide, if possible. However, I'm not sure what the players, or some NPC 1,000 years prior, might've done to earn the Raven Guard's trust, or what the Space Marines would do to honor it. As Chapters go, the RG aren't the most powerful, numerous, or anything, really. Ideas would aide in my story. Thanks much.