Pietro nods, listening to her analysis with interest. 

It doesn't have much effect given how tiny a joule's worth of matter is. Did the Grimm twitch, maybe? Hard to tell, given how it's been trying tirelessly but fruitlessly to wrestle free of its bonds since it got here. 

The anti-Grimm is still present inside it, though; it did not annihilate on contact. It rapidly migrates to the creature's skin and emerges, so small as to be invisible to the naked eye, but still detectable by Riley's analytical magic. It shoots out away from the Grimm as if repelled. 

A sample vial floats from her bag and she summons the mote into it before returning it. "Well, it seems that I can conjure inverted grimmstuff. It repels grimmstuff instead of annihilating it like I would have expected. I guess that's an avenue for future research. I wonder how a full creature made out of that would behave. That means I could also conjure raw grimmstuff and see how it behaves but that probably needs more thorough containment facilities." Just to test, she conjures a joule's worth inside the grimm to see if it reacts in an interesting way.

The guards pale and Pietro turns a wide-eyed look at Riley. "C-c-conjure raw Grimm?" 

The Boarbatusk has no opinions on this. The conjured Grimm is simply absorbed. 

"Grimmstuff is a form of exotic matter. It's not something I'll do lightly but being able to conjure it makes it easier to study in a controlled environment. I could conjure dust too if I wanted to." She carefully doesn't mention or comment on her small test. After that, she'll try emulating aura inside the grimm.

The creature doesn't seem to react to the aura at all. In fact, it doesn't even seem to disrupt the creature's internals. 

One of the Atlas guards is typing on her scroll and trying unsuccessfully to look nonchalant about it. 

Caroline's voice speaks in Riley's head. Please don't antagonize them. The Grimm are their equivalent to the plagues and they don't have a solution.

I'm not trying to antagonize them, I'll try to be more sensitive though.

"Unfocused emulated Aura doesn't seem to interact with the Grimm." For her next tests, she'll start trying to manifest a few joules of each type of dust energy she's observed. She'll start with the hard light she has an example of at hand. Maybe it'll be more effective than pure physical force.

Hard light is slightly more effective than physical force at jostling Grimm internals, but nothing too exciting. It is also very energy-intensive. Some other Dust types are varying degrees of explosive, though a few joules doesn't do much. A few types - earth and ice, primarily - create small slivers of their respective element inside the Grimm. 

"Hard light seems effective at slicing up it's internals, that's probably too expensive to be worthwhile though. Other types of dust aren't doing anything interesting when I emulate their effects." She tries conjuring dust next, maybe that'll have more interesting results.

Conjured Dust doesn't immediately explode. If conjured inside the Grimm, it sticks, embedding in the substance of its body. If Riley's measures are acute enough, they may detect a tiny increase in power from the Grimm. 

"Is it documented that Grimm can incorporate Dust into their bodies?"

"I've never heard of a Boarbatusk doing that, but I think some of the more obscure varieties have been known to..." Pietro hums and checks his scroll for a minute. "...yes, I remembered right. Are you saying this one was able to as well? That is concerning." 

"I only added microscopic amounts of dust so the changes are accordingly subtle I can't tell if it's somehow taken on a more elemental nature or just absorbed it as a power source."

"Concerning, but overall consistent with what we know of Grimm..."

"Is there anything your people have wanted to test or know but been unable to?"

"Plenty. You said no obvious detectable weaknesses, so that's one question out. Can they be repelled from an area? They don't seem to avoid positive emotions, more's the pity.

"Are there specific negative emotions they respond more strongly to? Our efforts there have been inconclusive. It's hard to tell from a Grimm's gross physical actions whether they're more attracted to someone who's mad or someone afraid. 

"What are they made of, and why does it act biological when it clearly isn't? Why do they disintegrate when they die? Why do their bone plates sometimes remain behind? Why is the armor on a live Grimm stronger than bone, when all our analysis has suggested it is, in fact, normal bone?

"Why do they eat people when they don't seem to derive or require sustenance thereby? Why are they so horribly destructive? 

"And of course the biggest question of all - where do they come from? How do they reproduce? People have been killing Grimm for millenia, but other than the occasional possibly-apocryphal story of a giant Grimm creating lesser Grimm, we have no idea how their population is replenished. No one has ever seen Grimm mating, breeding, or even undergoing mitosis. Why?" Pietro becomes rather animated during this last. 

Meanwhile: 

Starlight magic can make Grimm. There is only one other being on Remnant that can do that. Starlight magic can also make Dust, and as far as Ironwood knows there is no one on Remnant who can do that. The fact that this capability is not, objectively, the most dangerous one Starlight has shown does not improve matters. At this point Starlight seems to have graduated from "national security nightmare" to "planetful of new gods" and Ironwood simply is not equipped to handle that. The one person who might be equipped to handle that is on another continent, a fact which is prohibitive for Ironwood but merely an inconvenience for Starlight and their damn teleportation. Ironwood hates trying to be sufficiently cryptic over even secured CCT channels, but he needs to talk to Ozpin. He makes the call. 

"It's possible anti-grimm stuff in large quantities could be used to repel them. And with more study we could try to replicate that effect it's hard to know if it would be efficient though.

I can request someone willing to have their emotional state edited be sent to help test the Grimm's responses. I'm not sure how long that would take though and I'm not authorized to change anyone's emotions so I can't accept a volunteer.

As I mentioned, they're mostly composed of a form of exotic matter I haven't encountered before. As for why it acts biological that's a very good question. Either the biological emulation is imposed on raw Grimm stuff externally or it somehow self-organizes that way. I'm leaning towards some sort of external process though. It doesn't really have the marks of a more biological process of growth.

The Grimm bone is produced by having Grimm Stuff infused into the normal bone. I assume it then dissipates like the rest of the Grimm stuff does when it's killed. Given that I'm guessing that at least part of why they eat people is to get the bone. There isn't any indication of another way they could produce it.

As to the questions about origin and reproduction this Grimm doesn't seem to have a reproductive system so I'm guessing that the answer lies elsewhere." 

"You can edit em- of course you can, you make robotic people. 

"Grimm definitely grow, and they can even be scarred sometimes...still, this is all more than we've gathered so far. Thank you. 

"What else did you want to study?"

"At this point, I think it makes sense to move onto durability tests. I expect your people already have extensive documentation on how well kinetic weapons work but I don't think you've tested radiation weapons with the same thoroughness. If it survives that the next thing to test would be kinetic forces applied internally. Systems to do that at scale are harder to design but if they're more efficient it would be worthwhile."

"By all means. I'm sure my superiors will be delighted to learn of more efficient ways to kill Grimm." 

"Alright, I have equipment for this." A dodecahedron a bit smaller than her head floats out of her bag and positions itself in front of the Grimm. "Hmm, standard testing sequence 1000 nm down to 100 pm starting at 100 watts and scaling to let's limit it to ten kilowatts for now," she pauses for an objection then sends a message to the remote teams to start just as she says "Starting now."

A deeper voice than Riley's issues from the device "First test 1000 nanometers 100 watts left forelimb focused to 1-millimeter diameter. Firing for one second. Test complete. Second test 950 nanometers 100 watts adjacent target. Test complete...." Riley will stop it if she notices interesting results but otherwise it will continue down in steadily shrinking increments until it reaches 100 picometers then increase the power and start from 1000 nanometers again.

The Grimm twitches its leg, but the flickering array of colors doesn't seem to be doing any visible damage. As the wattage increases - to actually a bit less than it would take to give a human second-degree burns - the Grimm's skin starts to boil away with each one-second burst. The surrounding "skin", behaving more like putty than cellular tissue, gradually sloughs in to fill the tiny gap. 

Further testing reveals that the Grimm doesn't seem to care much about the wavelength of the light, only the total energy input. There appears to be a definite ratio of energy-to-volume-destroyed, but at the same time the creature's apparent mass doesn't seem to be decreasing as quickly as it should. 

Each successive power increase burns a little deeper. Around two kilowatts, the one-second burst pierces completely through the Grimm's leg. It's not easy to tell if the creature feels any pain, since it struggles and thrashes tirelessly throughout. The first wounds are completely closed by this point.