"...No one really knows why Uaine's Ratio doesn't seem to accept any numbers divisible by ten in such a violent manner. Though countless scholars have attempted to proof the subject; often at the expense of body parts. What we do know is that Dust really likes pairs, sets of four, pairs of pairs, and not much besides."

Ruby's lecture came to a close with that, and she motioned for Cinder to step forward. The other woman's part of the lesson was was almost entirely theory, calculation and a demonstration; which meant Ruby could have probably given it easier herself. Cinder was aware of this, of course, but it helped to be able to rest her voice for a bit. It also had the added benefit of ensuring Cinder was seen as an actual teacher by the students and not just the grumpy scarred woman who liked to glare at people from the corner.

Life was full of small sacrifices like that.

If she was being honest with herself, Ruby was enjoying having someone to offload actual work onto; and not just some poor, civilian graduate student in search of a letter of recommendation. Given just how volatile Dust could be, especially when intended to be volatile, it was a wonder why aura training wasn't a part of the curriculum for even basic pulviology. Really, she probably should have tried to encourage it far more than she had. Likely with the assistance of Blake, or Weiss if she was feeling spiteful.

Unfortunately, according to the various armchair experts in positions of academic power: 'Mrs. Rose-Schnee, just because you have the hammer of aura in your toolbox, does not make every safety problem a nail.' they would invariably say with some… variation. Then proceed to ask for her opinion on safety protocols during the next Dust-related explosion on their campuses.

Honestly, you'd think they had something against their students not blowing themselves up. But, she was getting distracted. As much as Ruby loved to gripe about various shortcomings in the world of academia; she also really wanted to see Cinder's presentation.

It was a relatively simple one, mix a few types of Dust, at the behest of a few select students, and try to test its viability.

Being the head of the entire Beacon weaponry department, Ruby could theoretically obtain any Dust imaginable as required. On top of a few unimaginable ones. The amounts of each were limited only by the time it took to create the batch sizes she ordered, and given her own vast facilities she could even create them herself; albeit in smaller batches with the use of an on-site spread of Dust types located directly beneath the classroom, and a small-scale mixer housed in a demonstration desk at the front of the room.

Being legally co-owner of the largest Dust distribution and research conglomerate on the planet didn't hurt when it came to state of the art teaching tools.

"Okay, let's start off with… Miss Lily, give me a base Dust." Cinder had reached the end of her explanation, and had begun searching for her volunteers.

Ruby's eldest, adorable golden shenaniganizer that she was, of course threw a curveball to start the experiment off with. "Growth, twelve Rings, forty-four percent purity." hmm, growth-base, wish I worked with it more, let's see how this plays out, Jei.

Cinder, with the help of as much training as Ruby could provide over the summer, near-expertly added the selected base to the mixing table's instruction set. The bionic arm working perfectly with the volumetric display. Maybe I should talk her into an eye, depth perception might come in handy.

"Next, Mister Ona-Dorned." Cinder snapped her attention to her next victim.

"Do I have to-?" the brown-furred boy began to question.

"No, you should not need to give a purity level. Miss Lily has previous education on the mixing of Dust, and growth Dust is a rather advanced base-mix. It requires a purity standard to ensure it will stop growing at some point. Stick to the Dust you are comfortable with, myself and Professor Rose can handle the measurements as needed."

"Okay, uh, Energy, with… four mili-"

"Mister Ona-Dorned. I've already lost one arm in my life, I don't intend to lose another to anything short of a second yet-unknown magical bloodline trait. Remember the lecture you were just supposed to be listening to: no divisibles of ten." Woo! Caught it in one, Cinder. Though you still have at least one more Dust type to bring you out. Ruby nodded her head once in silent approval for Cinder's benefit, and winced inwardly at the bloodline comment.

"T-twelve Rings then?" Fuz stuttered out, sounding entirely unsure.

"Good call, that's one pair down then. Next, how about Mister Carnation." Dick joke in three… Two… One…

"Binding Dust. Four Rings." awww. I mean, I can make a joke out of that, but c'mon!

"Hmm, alright. I've never seen these mixed together before, honestly. Professor?" Cinder seemed to think three was enough, and given the fact they set as a pair of pairs, Ruby found herself agreeing.

The mixing table was a wonder of technology, really. As Ruby approached to double check levels and predicted results, she always found the ease with which it created samples incredible; and reminded her of the early years of trying to do the process more by hand. Mixing Dust purely freehand was possible, of course, but the results varied widely. Even when she had moved away from trying to do it in-house, it could still take several hours to get a sample back from a spare SDC lab; turning the whole lesson into a multi-class event.

"While I've never mixed it in class, I know the effect of this particular blend very intimately. Let's lower the purity of the growth Dust down to, let's say sixteen percent, just to ensure we don't run into any von-Neumann issues. And other than that, I'll wait for the output to tell just what it is you've all made." As she made the necessary alterations to the inputs -binding Dust required special tools that it wouldn't, well, bind to it- Ruby brought up two things on the room's two side displays, leaving the center screen to show technical details of the ongoing mix.

"Now, I have two options while we wait. One is a video of just what happens when you don't respect Uaine's Ratio. Lots of explosions and screaming in that one; you're all trying to be Hunters, knowledge of disaster is part of that, even the traumatizing parts." A few students went from slightly interested to less than enthused, but at least one or two perked up at it.

Fifty-fifty chance between messed up kid, or desire to focus on disaster relief. Either way, I need to tell Coal. I wonder what being a student advisor for these kids is even like…

"The second option, is a montage of some past year's creations in action. Some are interesting, some are literally watching grass grow. That won't take up the entire waiting period most likely, but afterwards we can switch over to watching our current batch finish up. Vote now, kiddos!" As one, all the scrolls other than her own alerted those present there was a class poll to answer.

Strangely enough, the vast majority of the class had chosen to watch the grass growing. It really was weird seeing herself go from what looked to be far too young to teach a class, to her current appearance. Which, admittedly, she still felt she looked too young to be teaching a class.

Port had really set an unreasonable body standard in that regard.

Luckily, across the years only a few injuries had come from testing the Dust. Property damage, on the other hand… The closest to an actual explosion was no bigger than her own upon first meeting Weiss all those years ago. That had been the last year she tried to do the process on site before the addition of her desk too; it was probably for the best.

During the lull of just watching the new Dust settling and being agitated again, Cinder and Ruby had made sure no student was in need of additional help, but most seemed content to talk quietly or work on another project. This demonstration did technically take the place of the day's lab, but Ruby didn't feel the need to force her students to stare at a monochrome video feed of what essentially amounted to a robot sifting flour.

She wasn't evil.

"Right, Cinder, how was the date? Heard you two went to… oh, man, dangit, what is that place Emerald likes? They do that mask thing. I've been there, too! Gah. You'd think I would reme-"

"Foxtrot's."

"Thaat's it, Foxtrot's. How was it? I think they had really good Mac n Cheese. Or was that Bread Sandwich? No, they have that grilled cheese with peach slices…" Ruby knew far too many good places for food. It was actually becoming a problem, a cheesy, delicious problem. Cinder had a dark look cross her features at the question though. That's not a 'I had a ton of fun' look. That's a 'Yang is going to find out what revenge feels like' look.

Just as Cinder was opening her mouth to answer, a loud Ding rang out from the mixing table. The two of them quickly dropped the attempt at a conversation and moved towards the rude machine. As they reached it, a silver tube rose from below.

It was maybe as big around as a coffee mug, and about as tall as three stacked on top of each other. Along two opposite sides ran a clear glass indicator which currently glowed a deep green color. Ruby released the safety lock and inspected the finished product, even opening the top to look inside.

"Congratulations! You've all just created a batch of Bonding Dust. Known for its jade coloration and usage in all sorts of traditions. It's also got a few medical uses alongside. It is, by and large, completely useless in combat however. Can anyone tell me what any of its possible applications are though?" Ruby was slightly disappointed that so few students had apparently ever heard of the stuff. As she handed the unsealed container over to Cinder, she moved back behind the table and turned the displays to technical lists of Bonding Dust attributes.

"Really? No one here knows what Bonding Bust can be used for? Alright, not that surprising I guess, it's not exactly sold in your corner Dust shop." Even Cinder seemed slightly intrigued by the strange substance.

"Bonding Dust, as the name implies, is used to bond things. Unlike Binding Dust, however, it's a two-way street. Most uses of it, commercially, are in wedding bands; Both civilian metal rings, and Hunter Cloth accessories; like my belt, for instance. When charged with the aura of at least two people, it creates a kind of amalgam within whatever it's infused into, connecting the two and making something stronger than either one individually. Now, there are some weaknesses to the situation.-" Ruby saw a hand raise, but she couldn't be certain who was actually asking the question in the darned room however. "Go ahead."

"So, why not make like, a set of armor with it? Why keep it limited to just a small accessory?" Ruby was impressed, that was honestly a good question to ask, seeing as how most of the room had apparently just learned this new Dust could combine auras and make them stronger.

"It's not a good idea to use more than a small amount of Bonding Dust; a few complications can arise if too much is used at once. So while it is technically possible to infuse armor with Bonding Dust, it's a very bad idea. Bonding, unlike most Dust types, actually consumes aura when activated, and the more you have, the more it will take." From the shifting sounds, she could tell a few students at least got the picture.

"I'm sure most of you know legends about 'Aura Vampires' who would attack villages and drain people of their meagre auras, leaving them to wither away or sometimes be ignored by grimm, but otherwise pretty lifeless? Those are thought to be the work of Bonding Dust overexposure. No concrete tests of true scientific value have been run to double check, but some less-than-scientific cases have been discovered over the years. If you would like to know more on that subject, look up Arthur Watts in your free time. Be warned, that man had no respect for anything but his own ego." Cinder gave what looked like an unconscious motion of agreement at the dig. The class wasn't put in the same lighthearted mood however. At least I can end it on a high note.

"Outside of infusing objects with it, however, Bonding Dust has a slew of applications in the medical fields. Primarily in surgery and recovery. Because of its unique fusing abilities: it can be used to ensure any living transplant is accepted by the aura and "healed" to not be rejected by the recipient, ever. It can also be used to allow families otherwise unable to bear children to have genetic offspring. Using something from my life as an example once more: both of my kids are thanks to the use of Bonding Dust." That got some scribbles, whispers, and glances. Teenagers really were some of the potentially meanest beings on Remnant, after all.

"Unfortunately, that will have to conclude class for today, Bonding Dust is heavily regulated and we don't exactly have a way to demonstrate its use anyway, unless you'd like to hold a wedding and haven't told me. Because this is your first class of the week, I would like to remind you all that this coming Saturday will be the first time you can all sign up for the dance committee, as well as the opening of the class offices for nominations. Have a great day kids."

The students were gone before the lights even came back up to their normal intensity.

As Ruby was left alone with Cinder, a clear question on the tip of her tongue was interrupted. "When she was little we called her nickname was "Little Jay" but once she could spell she decided it was J-E-I to be more like her grandpa. Then she outgrew the "little" but "Jei" stuck around, Especially with Em." The explanation brought a flood of old memories back with it, nearly all of them warm. I need to visit dad soon, see how mom's doing too. Ruby was so caught up in her upcoming visit to patch she forgot to reset the mixing table before the next period began. It was a quick fix, but she had Cinder to worry about it now. Having a friend who knew what they were doing was the best sometimes.

Ruby considered her a friend at least, she hoped Cinder did as well.

At least Cinder had Aura in case she messed up.

A/N:

Exposition gotta exposit. But, at least I have a legit reason to explain things to the unlearned masses (of students) Ruby IS a teacher after all.

Sorry this one's a day late. I couldn't find a good ending I linked. Had to let it stew for a while.

So, Yeah, I forget if I left it all in this version, but Jei's full legal name is Jade Lily; after the color of the Bonding Dust.

As always I take your feedback and create a kind of amalgam and come back stronger!