So I'm contemplating using a Genestealer cult as an antagonist one of my upcoming sessions, but I'd like to use a twist on it by having the 'nids infect a different species. I've done a little reading to see if this seemed possible, and what there is seems to indicate that it could happen. I just can't find any instances in the fluff where it's actually happened. Anyone else know of any?

Genestealers have infected the Tau Empire on occassion. Some examples were in the old Inquisitor line from Specialist Games, with the Tau named character biography. The other is in a Ciaphas Cain novel.

The aforementioned Orks-Genestealer picture is a bit dated, when the Orks reproduced pseudo-sexually with birthing pouches, like kangoroos. Since that aspect of them has since been changed in a way that would make Ork-Stealers impossible, I'd consider ignoring that bit unless you are playing more towards older Warhammer, or coming up with a new explaination (infected spores?).

In theory, any species that reproduces sexually will be liable to be infected by the Genestealers. This includes from the canon species Eldar, Dark Eldar, Humans (including abhuman strains ratlings and Ogryns), Tau, Taurellian Dog-Soldiers, Hrud, Kroot, Demiurg, etc.

Vespid i'm on a 50/50. Iirc, they have a queen that produces all the eggs for their colony. I'm sure the queen could be infested to continously produce 1st generation offspring, but would it carry on to full generation? Not sure there. Maybe after the next queen is born?

For some reason, Magellan's picture isn't coming up on my end. I take it from context that it's Ork-stealers, so that's interesting and good support for the concept in general.

I was actually leaning towards the Hrud for my purposes. Kind of 'there's a Hrud migration, oh no!' on the surface, with a more dangerous threat lurking within.

Warp tunneling genestealer hybrids...that actually scares me more then a green Symbiarch!

Great, Hrudstealers? Can we nuke this thread so my GM doesn't see?

Gimme some Rak'Golstealers.

Even in the old lore Ork genestealers were one of the least desirable species. Essentially because so few Orks actually survived to breed and even when they did it only happened at the very end of the parent's life so there was no real way for the offspring to be concealed and cared for.

In the new spore lore they're probably still not particularly viable. An infected Ork is likely to shed infected spores for a considerable time period and over much large area leading to a lot more births of 1st generation genestealers but most spores end up being squigs and runts and a snotling genestealer hybrid just isn't that scary. Additionally without the parental support and in a violent society that instintinctively recognizes when something isn't proppa the offspring are unlikely to survive for a long time.

Now if there was just one infected Ork dumped on a planet alone so that the infected spore could create a hybrid orkology well that could be a different story.

I found some reasonable information about non-human genestealers here: http://wh40k.lexicanum.com/wiki/Genestealer_Hybrid
http://wh40k.lexicanum.com/wiki/Genestealer_Cult

Yeah, a number of races don't seem particularly suited for Genestealer-breeding, in my opinion. I won't hearken back to my "everything is written to only fight Humans" BS, again, but let's see:

Orks: covered pretty well. While the end result would be terrifying, the middle bits are like an underpants gnome's plans for money. If the Hive Mind could Zerg for a bit, and take adult specimens of Orks, encase them, and infuse them with Genestealer DNA, making a Kerrigan-esque abomination, that would be nightmare fuel, and they have used Orky DNA, if it is to be believed, as Biovores and their ilk are supposed to be based off of Ork strains.

Tau: I'd see this as practically impossible, personally. First, I see many Tau settlements as smallish (no source I'm siting, just how I see them), and in a smaller community, it can be harder to hide. Also, the Ethereals might feel something wonky, as their influence over the infected might shift. Humans are so vulnerable, in my experience, because there are so many, and so many of those are forgotten and uncared about. A group can go missiong, or just wander off, and no one cares. Many who later see them will just ignore them, and go about their own hurried, gun-to-the-head chores. tau are much closer, more community-oriented, and getting your group away, to covertly breed, would be tricky, especially if the Ethereal notes you are starting to go nuts. Lastly, the Tau are seemingly smart enough that I'd think they could figure it all out, and deal with the problem, for the Greater Good.

Eldar: I won't argue it's impossible, but I will claim that it would likely not happen. Eldar have much stronger wills, and I'd expect one to do the classic Elf in fiction thing, and just will themselves to die. Also, depending on how you rule Eldar breeding, even if the Eldar around didn't notice something amiss, and that's a lot of psykers to fool, even if you don't Shadow in the Warp, your numbers would grow slow. In my variant of fiction, Eldar breed something like fantasy gnomes; once in their lifetime, around the middle, and always twins. Those that don't get to the 400 year mark, or so, don't add to numbers, and lost children are a huge loss. Maybe not that stringent, but if Eldar didn't have some more convoluted breeding than Humans, I'd think they could shore up their numbers SOME more than they do. Again, that's just me. Their DNA might be part of Zoanthropes, but it might also be too wonky for Genestealers to tinker in; they were built to a template by the Old Ones, and altering that template might just result in broken, useless flesh-wrecks, rather than hyper-fleet, Legolas the four-armed flesh-blender. Also, they, too, seem to live more close-knit than an aspiring Cult might like. Of the races who know what Nids are, and are terrified of them, Humans seem uniquely jaded and internally uncaring enough, along with spread out enough, to allow a Cult to grow, without too many neighbors to notice your freak kids.

Dark Eldar: I'd think if it could be done, a Haemonculus would have already done it themselves. In fact, maybe that's something of what they already do do to their minions. I now choose not to keep thinking about it.

Unmodeled Races: I'm not going to even try with Stryxis, Rak'Gol, or the other races in 40k. I seriously don't know enough about many of them. Tinkering Stryxis might more easily notice, and I don't think Rak'Gol really have society, rather than roving bands of kill-crazies.

So it seems, at least to me, that Genestealers are likely to just stick with Humans. Like real-life parasites, we give them everything they need to survive, thrive, and kill us from the inside out.

I won't hearken back to my "everything is written to only fight Humans" BS, again

It's hardly BS, just **** and poor writing by GW & co. Why you feel the need to come with excuses to make it even worse is completely beyond me, however.

Tau: I'd see this as practically impossible, personally.

Except, it's canon already! =D Particularly, in the novel, 'For the Emperor', Part 4.

Edit: I listed the wrong article, it was POR’LA VIOR’LA KAIS’UAM, the Tau character sample.

Apparently there's a short story called Elucidium which at least mentions Hrudstealers and deals with other species being infected, so it sounds like I need to get the book that contains it as my next step.

I think one of my big questions, and it may have to be answered by me for my campaign, is how socially adaptable the Genestealers are. A patriarchal cult is easy to disguise as extremist Emperor worship, but would stand out far more in other societies. If they were to infiltrate a Tau sept, would they instead disguise their activities as 'for the Greater Good'? If they managed to infiltrate a Craftworld, could they disguise themselves by taking over an Aspect Shrine, for example?

And then, the question becomes what form that would take in Hrud society specifically.

One little thing, and I don't want this to sound like "who cares?", but sort of what is the point? The Imperium is not friendly with aliens, on the most part, and for every Rogue Trader willing to buy stuff from the Stryxis, employ Freebooters or Kroot mercs, or sleep with the hot Eldar Corsair they met recently, there are literally millions of xenos-hating, God-Emperor-fearing people who know next to nothing about aliens. How would most any Human encounter "Hrudstealers", and even have reason to know that they are acting strange? It's interesting to see how some folks feel about it, but I guess what I'm getting at is how might you use it? Alien crew might notice more, but if you are Humans, and only deal with the "average" Rogue Trader alien traffic, you probably won't know, and the Imperium would quietly giggle if Genestealers began eating Orks, at least sort of.

Now, please don't take this as me being a jerk, but yeah, just a bit of "how might you find this useful. It's one thing to say "I want Orks Nobs with four arms, slavering jaws, fleet of claw, acid guns, and a Hive Mind", and another entirely to say "my crew is going to go all DH, and somehow stumble on a Genestealer Cult hidden among an alien culture we were just happening to be walking around in. It could all get very interesting, if the Genestealer part doesn't just TPK the group. Good thing RT is accomodating with gear.

If I'm to be 100% honest, part of it is just obsessive worldbuilding. So while I could just slap genestealer bits onto some Hrud and call it a day because why not, it would feel... I dunno, empty to me personally as the GM. I don't like going 'there are monsters because monsters, and that's it, now kill them and hush.'

That aside, there are a couple of reasons why this is useful to my particular game. First, one of the party has made it a point to specialize in Forbidden Lore (Xenos), so it creates a fun situation where they might know how Hrud usually act, and be worried when these aren't acting normal.

Second, one of my players knows 40k lore very well. She's great, she doesn't metagame, but I know she's a little sad that she doesn't get the same twists and surprises the others do from not knowing what's up at the first sign of things. So I'd like to be able to spring a surprise on her and give her some of that fun.

Perhaps most importantly, my group isn't really a 'slaughter the xenos and call it a day' party. If they hear there's a Hrud migration happening, they'll be interested in investigating in more depth to find out if they can profit from it in some way. I guess they really are the 'deal with Stryxis, hire the Kroot, romance the Corsairs' types. In fact, one of my players has admitted he really likes the Stryxis, even though I've done my level best to make them utterly creepy.

Anyways, that's probably tl;dr, but you asked why/how it would be useful to me so there you go.

The short story Elucidium deals with Eldar/stealer hybrids. Apparently Eldar biology is noted being less crude compared to Humans with the Genestealer taint taking many generations before producing a primacii mutation. By the time this is discovered, the vigilant Eldar manage to eliminate the hybrid community which is quickly discovered and destroyed.

Seems like any civilization with reasonable psychic presence like the Eldar or even the Orks would make for a difficult infiltration.

A colony of abhumans like Ogrins on the other hand would probably make a fine civilization to infiltrate.

If I'm to be 100% honest, part of it is just obsessive worldbuilding. So while I could just slap genestealer bits onto some Hrud and call it a day because why not, it would feel... I dunno, empty to me personally as the GM. I don't like going 'there are monsters because monsters, and that's it, now kill them and hush.'

That aside, there are a couple of reasons why this is useful to my particular game. First, one of the party has made it a point to specialize in Forbidden Lore (Xenos), so it creates a fun situation where they might know how Hrud usually act, and be worried when these aren't acting normal.

Second, one of my players knows 40k lore very well. She's great, she doesn't metagame, but I know she's a little sad that she doesn't get the same twists and surprises the others do from not knowing what's up at the first sign of things. So I'd like to be able to spring a surprise on her and give her some of that fun.

Perhaps most importantly, my group isn't really a 'slaughter the xenos and call it a day' party. If they hear there's a Hrud migration happening, they'll be interested in investigating in more depth to find out if they can profit from it in some way. I guess they really are the 'deal with Stryxis, hire the Kroot, romance the Corsairs' types. In fact, one of my players has admitted he really likes the Stryxis, even though I've done my level best to make them utterly creepy.

Anyways, that's probably tl;dr, but you asked why/how it would be useful to me so there you go.

Yep, this is what I wanted. Thank you I can appreciate chunks of it, too, because while the Imperium is all burn the xenos/mutant/witch, I personally DO see the value in diplomacy, cooperation, and what have you; the Imperium really could do with some allies, for a change. While I don't know how radical/heretical your group is, in regards to alien interaction, it is nice to see something more in depth than "does it have pointy ears? Kill it!!!"

For more information on why the Imperium likes to burn xenos, look up "the prisoner's dilemma".

any ideas on how a Shardikoa/Genestealer hybrid would do?

any ideas on how a Shardikoa/Genestealer hybrid would do?

Hurt anything it managed to get into close combat with?

any ideas on how a Shardikoa/Genestealer hybrid would do?

It seems like it would basically never happen. Shardikoa travel in small groups so they make terrible hosts as the 'infection' would be difficult to spread.

Shardikoa breed very slowly so the 'infection' would be difficult to spread.

Shardikoa have inbuilt nanite technology so the 'infection' may not actually take.

All in all I think genestealers would just kill any Shardikoa they encounter as it seems like they're not worth the effort of implanting.