At this point in my campaign the players are about to witness the launch of a retaliation fleet formed by the Mechanicus, more specifically the Divine Light of Sollex Cult under the leadership of a new Archmagos, against a group within the Expanse. It is not uncommon for such a force to be accompanied by Space Marines to provide extra support.

Which Chapter within the immediate vicinity would be most likely to respond? More importantly perhaps, which Chapter would also be an interesting group for RP when the Explorers arrive at Port Wander where the fleet is massing and interact with them.

My first guess were Storm Wardens and Iron Hands as they are both close by, yet I know little of the Storm Wardens beyond what Deathwatch has taught me and from that they seem too secretive to provide a force to such a large and very public endeavor. Meanwhile with the Iron Hands I see the problem of having the Space Marines act too much like their Mechanicus allies, I feel like I would just be playing the same vibe as the Magi of the Sollex Cult just in power armour.

Next on the list would be Imperial Fists, but do you guys have any suggestions for me that I may have overlooked?

An Imperial Fist marine is a side character in a Rogue Trader module (Soul Reaver), so you could always use them if you plan on running it as well. That way, you can tie them together. Otherwise, your preference is as good as mine.

Ah yes, I completely forgot about him... hmmm, and one of my players does have a backstory that involves a run-in with the Dark Eldar during the Periphery War. Thanks for reminding me man, this just opened up a few more options for me.

Storm Wardens are based nearby.

I created a chapter from scratch for this purpose. That was 2 campaigns ago. I've never used them but they await on standby should I ever need a dramatic moment.

While the idea sounds enticing I feel like a scratch-built Chapter will not have the impact I really want out of a meeting with Astartes, my players are all pretty well-versed in 40k lore so they may well feel cheated if I involve a Chapter with no background in the setting.

However Errant, I would enjoy any advice you have on running a social encounter with even a small group of Astartes. I know a lot depends on the Chapter, though as of right now I am pretty much set on Imperial Fists. Regardless I will gladly take further input.

I suppose it might partly depend on what sort of altercation is about to happen, and what caused it (the fight between the AdMech, and whomever), but one advantage of the Astartes is their small number. Where I'm going with this is that many of the Chapters are widespread, so Blood Angels, Ultramarines, or White Scars could all just as easily show up, if you don't need too many individuals, and even the AdMech can find it hard to request too many Space Marines; Techmarines can keep their gear working fine, if the AdMech tries to leverage that against them. For my bit, I'm rather a fan of the Salamanders. My take on them, at least, is that they are a little more human than their other brothers, where the AdMech can be very mechanical, but they are also very well-versed in craft, which could keep them in good with the Tech-Priests. Also, and I hope this doesn't come off as inappropriate, Salamanders, at least in art I've seen, look a bit less "human", with the shape of their facial features, being more like the big Maoi heads, on Easter Island, than just big African American, or even African Space Marines, and the glowing, red eyes, and DARK brown, all the way to coal black skin further differentiate them from the more utilitarian Ultrasmurfs, or the extra pretty-boy Blood Angels. A nice combination, at least to me, of more than human, and still able to relate to, and care about them. They can be slow, planning, and methodical, possibly keeping the AdMech from more ruthlessly hurting bystanders, if it gets them toward their goal. Of course, some of this might as much just be my fanboy take on the Salamanders, but there you are.

Regardless, if there is a Chapter you like, you can probably come up with a reason they could be the ones involved. The Deathwatch isn't the only way Space Marines cover staggering distances, and receive weird assignments, throughout the galaxy. Maybe the Salamanders heard one of their Primarch's lost relics could be in that area, or the Dark Angels are ALSO responding to Fallen Angel activity. Maybe the Thousand Sons have been known to be in the area, sometime, and some Space Wolves thought they'd come along, just in case they got a chance to clash with the empty suits, or their Sorcerer leaders. Whomever you pick, I hope it turns out well; just remember not to use up the awesome that is getting to see the Astartes, or they'll lose the allure. You said your players are well-versed in 40k, so maybe that's not an issue, but I thought I'd mention it, anyway. Mt. Rushmore is a very impressive, for instance, and draws in many tourists, every year, due to its historic significance, but it loses a little something when you happen to live in that state, and see it all the time.

Thanks for that Venkelos, and I can tell you I enjoy the Salamanders a lot myself. Hell I play one in a DW game

However I have decided on the Fists for this one with an added subplot about the Dark Eldar.

You are very correct about not overusing the Astartes, and I have planned for their appearance to be a major occasion for the party.

Honestly it would be odd for any one Chapter to be operating in the Koronus Expanse because it's one of the most remote regions in our Galaxy that has yet to be claimed by the Imperium, and until recently it was completely impassable so there shouldn't even be any Chapter Relics in there. At least all of that should be the official history...

The fact that it's a Mechanicus fleet means you could have the Iron Hands or one of their Successor Chapters there for support, as those two have reasonably close ties. They're still allies but not bonded at the hip, so they might not be granting full co-operation. The Ciaphas Cain novels mention the Reclaimers who also love exploring for old Archeotech, although they're also presumably based in the Eastern Galaxy.

The Space Marines operating out of my Expanse are the Black Consuls, who are trying to seek a lost Strike Cruiser and, much more importantly to them, the gene-seed of their fallen brothers that might still be intact on board. Given that there are so few of them remaining, finding this craft could be the difference between their Chapter coming back from the brink or being lost to the ages. If the MYSTERY GROUP your players are crusading against are rumoured to have the gene-seed (perhaps a rumour planted by the Mechanicus which your players could discover) then that might compel their co-operation.

Edit: I mixed up Black and White Consuls again. I suggest Black Consuls, though you could run this with any diminished Space Marine chapter.

Oh no do not think that the Chapter in its entirety will be present for the campaign. Currently I am looking at a force of three squads from the Imperial Fists' 3rd and 6th Companies with a Veteran Sergeant seconded from the First Company acting as overall commander.

I must say I have not heard of the Black Consuls, though then again my knowledge of Space Marines beyond what appears in the Imperial Armor books and the Codexes is limited hence why I posted for advice on the thread.

The Black Consuls are an original Ultramarines Successor chapter, and one of the Adeptus Praetes - an Astartes Chapter assigned to watch over the Eye of Terror. In 455.M41 the majority of their Chapter was destroyed in a trap laid for them by the Iron Warriors and the Word Bearers when the Iron Warriors detonated a Hive and levelled a continent, wiping out all the Black Consuls present.

Though some Marines were elsewhere and survived, there were few enough survivors and almost no gene-seed recovered that the Chapter was declared Destroyed, but not Extinct. Those that weren't dead were allowed to either join another Imperial institution (such as the Deathwatch), merge with an existing Chapter, or try to seek a way to restore their Chapter. I feel they're appropriate (and in small enough numbers) that they could be reasonably encountered in a far-flung place like the Expanse.

On second thought, I did use Astartes a couple times in campaigns. I used some Dark Angels looking for Fallen to brutalize the PCs and turn their sympathies against all Astartes in general. That part worked. The DA were a ruse to send the PCs off on a red herring hunt. That part didn't work, which is unusual...my red herrings have a good success rate. Obviously I didn't prod the greed factor hard enough.

I also had a DW Salamander Apothecary demand passage on the RT vessel. That was another red herring, but in our present campaign, so I reserve the right to pull him out of obscurity for a future dramatic moment. You might get the idea that I only use Astartes for dramatic moments and red herrings. This is true. PCs are the major players in my games. Introducing Space Marines without making them dominant personalities wouldn't seem true to the genre, while bringing them in as major players would eclipse the glory of my PCs. I don't like either option.

If I were going to use an Imperial Fist, I'd like the idea of my PCs stumbling on some ancient hidden good/evil (take your pick) secret that a team of Fists had been tasked with guarding. Unfortunately for them, the ship that left them at their post didn't make it home, and no record exists of their mission. Only 1 remains, the rest having died of old age or what have you.

But I doubt I'd ever use Astartes in a supporting role. They don't play that part well. Even the Salamander passenger was requested by the PCs to man their ship's guns. I knew right away I had to ditch that NPC.

**** that's harsh Errant. Well the story for their being at Port Wander is a simple one, they are providing military advice and support to the retaliation fleet.

The plot is currently that the Explorators of Illusk have turned traitor and the Sollex Cult capitalised on this to finally launch a strike against the upstarts. The Fists will play a minor role for now though what the fate of the fleet will end up being is something that the direction the plot takes will decide.

As for Astartes being poor in support roles, I would say its about keeping their deeds from interfering with the PCs story. Marines are great as a force of nature, changing up the environment and forcing the players to react accordingly. At least that is how I am running it for the time being.

That was what I took the Marines' role to be. A Space Marine is even less vulnerable than a human to the kind of ridiculous lies your average Rogue Trader will come up with. You can spin them a story about how they've found a relic of their Primarch that you want them to succeed. If you manage to pull that off, then they'll thank you and then go do it themselves insisting that an outsider should not come along. And then when they find out you lied they'll come back and kill you.

Good times.

Consensus seems to be:

Occasional Death-Watch

Storm Warden Scouts

Star Dragons

others from the Angevin Crusade may lurk

Other People's Opinions:

LINKA

LINKB

LINKC

LINKD

LINKE

Well ****, I wasn't around to post back then but woah. Didn't know this topic had been covered this extensively. Thanks for the links though, much obliged.

Technically, there's a Grey Knights Strike Cruiser tooling around in Koronus/Calixis for some reason, too, but unless there's significant daemonic involvement, or someone/something they're actively looking for is somehow involved/connected, the Grey Knights are unlikely to have any sort of interaction with events, unless they have a prophecy. Plus, of course, even if they did, you'd have to deal with their habit of mind-wiping and/or killing witnesses to their operations (admittedly, that's at least partly due to the fact that they normally deal with daemonic incursions, and that's just a standard countermeasure when dealing with such things).

However, I would strongly advise against utilizing the Grey Knights - they'd likely be just too disruptive. I could maybe see them reaching out to a Rogue Trader in pursuit of information or relic hunting expertise, albeit likely through an Inquisitor/Inquisition Agent as an intermediary, but such a situation would be extremely atypical at best.

That was what I took the Marines' role to be. A Space Marine is even less vulnerable than a human to the kind of ridiculous lies your average Rogue Trader will come up with. You can spin them a story about how they've found a relic of their Primarch that you want them to succeed. If you manage to pull that off, then they'll thank you and then go do it themselves insisting that an outsider should not come along. And then when they find out you lied they'll come back and kill you.

Good times.

Yes and no, I think. Depending on the Chapter, and the individual Astartes's experience with regular humans, they may or may not be as gullible as a regular human, or at least, they may or may not be as good at spotting spoken lies. The Chapters that are least connected to normal human humans, with the least amount of interactions with normal humans are likely to be less good at spotting the lies, because battle-brothers in a Chapter would almost never lie to one another - if there's something they can't talk about or something you're not supposed to know, they're likely to just say that they can't talk about it rather than lie about things. This is hugely variable, though.

Of course, I absolutely agree that if/when the Astartes finds out you lied to him in order to get something out of him/his Chapter, the consequences will be most severe. An example will be made out of you ... or what's left of you. Either way, deliberately lying to an Astartes in order to get something from him/his Chapter is generally a terrible idea. It's probably worth lying to an Astartes if you'd rather not tell him about the contraband/illicit/illegal materials/technology you've got, or at least, skip the details.