So I was thinking about letting a Grey Knight into a Deathwatch campaign. I've read in Daemonhunter that Grey Knights don't worry about requisition costs and only need to meet the renown requirement, but I swear I've seen somewhere that said Grey Knights will only get half the requisition that the other Space Marines get. Is that real or have I subconsciously made that up?

Theres nothing in the Deathwatch books about it, the thing is though that Daemonhunter (using DH rules) is likely a bit of a difference to DW rulings. You can go with that if you want but I can't quite see why they would only get half the requisition of anyone else. Additionally I don't see why just because they would be renowned enough they can take anything they like. Both rules are equally flawed if you ask me.

The suggested guidelines for integrating a Grey Knight into the Deathwatch system of requisition is found on page 131 of the Daemon Hunter rulebook.

While it says requisition isn't important, that is for a Grey Knight operating from Titan. If he were away from his normal supply lines (i.e. Titan) then he would need to get his gear from other sources (i.e. watch stations) which would require requisition.

I would buy it. Grey Knights start with pretty high-end gear, such as the wrist-mounted storm bolter, possibly better quality armor with Hexagramminc wards, a Power + Force weapon, and such; seriously, what more do they need to requisition? I suppose that they might want a teleport pack, or one of their psycannons/incinerators, but the DW might not be THAT well equipped. I think they'd have half req so that, starting with awesome, they don't let someone else use up their "left-over" Requisition points (I seem to remember that they are communal points).

I kind of wonder, can the Watch Commander really boss around a Grey Knight, like he might other Space Marines? Depending on the source, GKs are like a step above "average" Astartes, and the only ones who can directly battle Chaos, when the CSMs bring their Daemon buddies. Would that be led around by some goofus off-Chapter Watch Commander? I know he's the Watch-Commander, and NOT a goofus, but he's some BS Chapter, if my memory serves, like a Son of Medusa, or something, though thank god, not a Blood Angel, which is what I had expected when I first got the book. Would an independent Grey Knight, who now doesn't even truly answer to the Ordo Malleus, have to take orders from the DW, or just choose to be there, on retainer?

I kind of wonder, can the Watch Commander really boss around a Grey Knight, like he might other Space Marines? Depending on the source, GKs are like a step above "average" Astartes, and the only ones who can directly battle Chaos, when the CSMs bring their Daemon buddies. Would that be led around by some goofus off-Chapter Watch Commander? I know he's the Watch-Commander, and NOT a goofus, but he's some BS Chapter, if my memory serves, like a Son of Medusa, or something, though thank god, not a Blood Angel, which is what I had expected when I first got the book. Would an independent Grey Knight, who now doesn't even truly answer to the Ordo Malleus, have to take orders from the DW, or just choose to be there, on retainer?

Really venomously hate the silver cheese knights.

The GK is a military arm of the Inquisitionary Ordo Malleus. The Deathwatch are the military arm of Inquisitionary body Ordo Xenos. GK and DW are technically higher in the pecking order than the average Adeptus Astartes because they are tied to the Inquisition but their respective rank and status is identical to each other and therefore neither has any power over the other in the same way that inquisitors from each branch don't have effective power over the other. If however a commander of a watch fortress tells a marine to do something then ordos be damned they will be required to follow it. It's their station and their rules! Disagree or commit insubordination and they have every right to throw you into the brig/nearest airlock assuming they don't kill you first.

However I disagree that the GK are the only ones which can battle a daemon. The GK are perhaps the best people for the job due to training and sanctioning but that's about it and would never say they are the only person for the job. Any marine can take on a daemon but the GK are better at it just like anyone can kill an alien but the DW are better at it due to superior training.

Also, you say that with their warding, force weapons and gear they don't need anything else. I would like to see the oh so mighty psychic warriors of the GK take on a squad of Necron Pariah or tackle a Dark Eldar which deploys a crucible of malediction. Is that the sound of your GK's head exploding because he can't use his psychic abilities? I can't say I agree that they start with the perfect gear really and the DW arsenal contains a wide variety of more useful gear such as exotic weapons, sniper and las weapons to destroy their enemy from afar, potent explosive charges etc.

If a GK were assigned to a DW station for long term assignment (aka multiple missions) then they should use the same requisition as everyone else. DW doesn't have extra stun grenades to hand out like candy just because a GK is there.

Also, A GK would likely keep his identity a secret. Very few know of the GK existence and they're not going to go around blabbing it to the staff of another ordos. Likely the GK would come in with the black shield.

If however a commander of a watch fortress tells a marine to do something then ordos be damned they will be required to follow it. It's their station and their rules! Disagree or commit insubordination and they have every right to throw you into the brig/nearest airlock assuming they don't kill you first.

However I disagree that the GK are the only ones which can battle a daemon. The GK are perhaps the best people for the job due to training and sanctioning but that's about it and would never say they are the only person for the job. Any marine can take on a daemon but the GK are better at it just like anyone can kill an alien but the DW are better at it due to superior training.

Also, you say that with their warding, force weapons and gear they don't need anything else. I would like to see the oh so mighty psychic warriors of the GK take on a squad of Necron Pariah or tackle a Dark Eldar which deploys a crucible of malediction. Is that the sound of your GK's head exploding because he can't use his psychic abilities? I can't say I agree that they start with the perfect gear really and the DW arsenal contains a wide variety of more useful gear such as exotic weapons, sniper and las weapons to destroy their enemy from afar, potent explosive charges etc.

Grey Knights, like most other Astartes, are hyper-trained/indoctrinated to follow orders, so yeah, I suppose if a GK was seconded to the DW, he would understand that his orders come from the Watch-Commander. Recent stuff, however, seems to have distanced them from their OM "masters", making them more autonomous, sort of like the Deathwatch is now represented, receiving aide from the Inquisition, rather than taking orders from them. Less "Militant Arm", and maybe more "if they feel like helping us" asset.

I'm not saying that Grey Knights are the only ones who can, sorry. They are the ones EXPECTED to. Other Astartes have the skill, the weapons, and such, but they are rarely sent to do so, with that in mind. Way too many Astartes have fallen to Chaos, over the millennia, so they are the best typical option, but still risky. Grey Knights go in knowing they'll be fighting Daemons, and none has even fallen, so they can face down the worst Chaos can throw up, and stand against it, either killing it, banishing it, or, kind of more likely, dying fighting it. And i will say, based on playing 40k TT, Daemons were often the ONLY thing Grey Knights pwned against, as Chaos Space Marines, especially those Noise Marine bastards with their cheesy weapons, and heightened Initiative, ALWAYS seemed to win.

While the codex will piddle, because the folks at GW don't want you to hold on to your money, I think it is a fair thing to say USUALLY Grey Knights won't fight Necrons; that's not their specialty. Grey Knights are few in number, and dispatched to a place Daemons are already a problem, or guarding a site where they could pop up (Fall of Shadowbrink, for instance). While it makes them sound a bit less fun, they don't often fight other stuff. Their gear does seem good for fighting Daemons, and they let others fight other stuff, when possible. Of course, only my opinion.

If a GK were assigned to a DW station for long term assignment (aka multiple missions) then they should use the same requisition as everyone else. DW doesn't have extra stun grenades to hand out like candy just because a GK is there.

Also, A GK would likely keep his identity a secret. Very few know of the GK existence and they're not going to go around blabbing it to the staff of another ordos. Likely the GK would come in with the black shield.

Someday, I'll get over this silly aspect of the Grey Knights, and their big SECRET!!! that every enemy already knows about. It isn't today, of course, but maybe someday...

Meh. Every Table Top player knows about them. Honestly I didn't even know about the Grey Knights until recently. Let me summarize my views on how others see the Space Marines, and the distinctions between various chapters.

Orks: Deyz da humies wot fight hard, and gotz good kunnin, right? WAAAAGGGGHHH!!!

Tyranids: Crunchy food. Unless they came in Rhinos (or other vehicles), in which case, Canned Food.

Necrons: YAWN. Did someone wake me? Who are these guys, and where did they come from?

Eldar: I know this is going to make me sound racist, but the lesser races all look alike to me. How are you supposed to tell them apart again?

Dark Eldar: Hrm? They sometimes have different paint schemes on their armor? That's fascinating, I suppose, but I've been working on cataloging the differences in the way they scream when tortured. I'm writing a novel on it.

Tau: I liked working with the Blue ones, hopefully we shall have the opportunity to work together again. Most of the others seem extremely unfriendly, and extremely dangerous.

90% of the Imperium: I've heard rumors of these Angels of Death, but I've never actually seen one. I wonder what they're like?

IG / 9.99% of the Imperium: Yeah, I've seen them, and "Angels of Death" is accurate. They say jump, and you don't ask how high, you just jump! Let me tell you about my encounter with them, I'll remember it for the rest of my life....

So basically, the way I see it, for most of the creatures in the universe, they simply wouldn't care about the organizational structure of the Space Marines. For the rest, even if it was not a secret, they wouldn't have the consistent exposure needed to have discerned it on their own, and there's no way a Space Marine would tell them *anything* about themselves, with Hypno Indoctrination meaning they wouldn't divulge any information, regardless of its relevance, even during torture.

I challenge you to provide to me an example of the experiences or interactions that would result in any of the aforementioned groups having knowledge of anything more than "Man, compared to those guys with the U, these guys with hands on their shoulders are jerks". And that's even without any active efforts to deny anyone information, so I think the whole secret thing is ridiculous, but from the other side of it- it's completely unnecessary.

Is it possible that someone within the Imperium, with an unusual combination of intelligence, access to knowledge, and freedom could find out about them (such as a Rogue Trader, Planetary Governor, etc)? Sure. But not only would those individuls be exceedingly rare, they have no reason to divulge that information to others. Not just because it's "forbidden lore", but also because anyone who went to the great pains to learn abut that would be giving up the fruits of that effort and the perceived advantage that knowledge is supposed to (somehow) bring them, so they wouldn't do so without significant compensation, requiring a similar individual to be able to know the right questions to ask, and have the resources to compensate.

Ironically, the only ones who would have a chance of knowing about them, possessing the right combination of interest and repeated exposure, would be the forces of Chaos. They have knowledge of the organizational structures of Space Marines, they care almost exclusively about the Imperium of Mankind, they face the Grey Knights with 10x greater frequency than anyone else does, and they have the greatest ability to infiltrate the Imperium, to generate resources, and to trade those for the kind of knowledge that they would perceive to give them an advantage over their foes.

tl;dr: In terms of the "secret that every enemy already knows about", sure, the enemy they face day in and day out has the motive, means, and opportunity to already know about them. Practically everyone else in the universe does not know, and very likely, does not care.