"Sublayers?"

"In my universe the primary space-time 'layer', which is where we are now is adjacent to other usually empty space-times which we call sublayers. It took a really long time for us to figure this out since magic makes heavy use of a couple particular sublayers and something, which we think is also magic, makes it all but impossible to visit those sublayers. There are projects underway to work around that interference but we haven't succeeded yet."

"Cooool, and these sublayers are what? Different universes or something?"

"It's a little bit unclear to be honest. Sublayers, near as we can tell are totally empty except for matter moved into them from primary layers. Gravity also propagates between sublayers and the primary layer. That doesn't happen between universes connected by the threadwork so we don't call the sublayers separate universes. I'm not sure if you've heard of Dark Matter but some scientists think that at least some portion of it is in one of magic's sublayers." 

"Huh, I can't say I really get the science side of it. I wonder how much of your future knowledge would help us. Not only for technology, but maybe how to," she makes a vague wave gesture, "adapt to new kinds of magic. Back in my world the magic has just become known to the public a few months ago."

"I would not be remotely comfortable condemning another world to unsupervised singularity trials. Hopefully that's one of the things that only happens on the Earth I'm familiar with. As for how to adapt to magic, given how much the singularity trials changed things I'm not sure how much advice would be applicable given that we discovered magic after those had ended." Zahn sighs. "Still I'd be happy to offer whatever advice I can, finding new cultures and opening diplomatic relations is my job."

"Singularity trials?" She asks distracted again.

"So, around 2030, genetic engineering really took off in a big way, people figured out how to genetically engineer things with a lot more speed, precision, and ease than they ever had before. Unfortunately, the leading edge of this work allowed anyone with a grievance to engineer custom biological weapons and release them. Some places including my current employers suspected this might happen and so had filters good enough to keep their people safe but most people didn't. A lot of people died. Current estimates are that about half a billion people died from the plagues before governments and charities managed to distribute enough countermeasures to keep people safe. The only thing that stopped those numbers from being higher is that most of those plagues were targeted to some ethnicity, or genetic disease, or heck there was at least one plague that targeted people with blue eyes. I wish I could say that was the end, but really it was just the beginning. In the scramble to address the plagues nanotechnology advanced by leaps and bounds and not all of the discoveries there were friendly either. Some cities ended up being nuked to contain particularly dangerous nanotech. At the tail end of that mess, someone cracked human uploading, which resulted in a lot more panic but thankfully a lot less death. All told by the end of the Trials over a billion people had died either from direct effects or from disrupted ecosystems leading to starvation and other such lovely knock-on effects."

"Wow. And I guess your world's experience isn't going to help that much. All that we have to face is the sudden appearance of hate-monsters, magical girls and a woman that could be confused with the second coming of Christ."

"Tentatively that sounds a lot less dangerous, I don't really like the sound of hate-monsters though."

"They are more... monsters made of broken promises and sense of betrayal, but that isn't as catchy as hate-monsters. They are hard to deal with without magic and get stronger over time, nowadays, the population of Oathknights is large enough that they can be dealt with in the same day. I would even say that most of the problems are more social."

"Well that makes me feel better. I take it that that's what your sign is about? You want to become an Oathknight and the process includes binding yourself to a magical oath?"

Nod. "Yeah, 'binding' might be an oversimplification but there was no simple way of putting all the relevant details in the sign. ...Do you want the full explanation? It involves some historical facts."

"I'd love a historical explanation."

"Alright, so our magic works by making oaths. You make one and the magic sort of helps you fulfill it. Typically the effect of this are very small and breaking promises diminishes it. However an alien species discovered a trick. Making oaths and ask-slash-wish for the benefits to accumulate as a sort of reserve, with the option of transfering the benefits to other people as well. It still took generations, but they eventually managed to harness the power for interesting effects."

"However, there was a downside to it, the greater the power, the greater the backslash, creating curses, bad luck and monsters made of magic. The aliens tried to patch that up, but the magic was smart enough to pretend and attack later. Soon the entire species was essentially cursed."

"To avoid the complete doom of their civilization the aliens explored the universe until they found humans, then they used bio-manipulation to interbreed with humans, purifying the descendants and creating a new human subspecies that is nearly identical, except for a thin white line around their iris," Temperance points at her own eyes, albeit it's hard to notice without getting closer, "things were mostly fine for a while but the corrupt magic was playing possum again or maybe breaking promises got worse. They created the Oathknights, which was a group of magic users with the specific purpose to fight the effects of corrupted magic. They also tried to patch it with regular visits to Earth to get uncursed people, but the problem got bad enough that all they could do was basically evacuate to Earth and seal off the portals to keep the corrupt magic out."

"Some of that magic still escaped to Earth and would try to open the portals again, the Oathknights dedicated themselves to prevent this. Except that a few months ago the corruption came very close to succeed. But there was an Oathknight - who of course was also a princess - managed to prevent that. Oathknights get powers based on their oaths and hers included the line 'to be the light that stands against the darkness', so that manifested itself by sealing off the portals much more strongly at the cost that she is now in a coma. And also her magic is manifesting itself as the Lady of the Oaths, a figure that goes around saving people and offering them the chance to become Oathknights and fight the extra monsters that have showed up because some extra corruption magic that escaped."

zabna blinks slowly twice. "Well then, your magic sounds really unfriendly. Like magic in my world often does terrible things but I've never heard of it being malicious in its own right."

Temperance shrugs. "I can't say I like the downsides. One thing of note is that Oathknights have a specific Oath format, the first and fifth lines are predetermined and the three middle lines are picked by the specific knight. The Lady offers a new kind of Oath with a different final line, and the knights that go by that one don't appear to experience negative effects from corruption except by diminished powers. One of the things I am considering is which version to pick."

"So, you're saying that using your magic is also to some extent fueling the very thing you're fighting against. I guess it's too late to wonder whether this Pandora's box should have been opened but wow I don't like the implications that has for your world." He sighs. "What sort of powers do Oathknights have? How much of a difference do the two final lines make?"

She actually has those written down.

The original version is thus:

This is an oath to fight injustice. May I never break it.

While the new version is:

This is an oath to bring hope. May I do my best to be worth it.

"There is a sense where specific knights can influence their own interpretation of the Oath, but these specific words sort of... tie the first Oath in a sort of aggressive role and make it rather inflexible. The second Oath is more... forgiving? And generalized in a rather positive direction. On the other hand, it is known that Princess Felicity - the girl that sealed the portal - and her twin - of course she has a twin - made their Oaths interpreting 'to fight injustice' as meaning 'to work hard against bad things, because everyone deserves good things' and that apparently helped them to get more versatile powers."

"As of powers that Oathknights might get, it varies a lot: healing, elemental control, super-speed, flight, weather-control, ability to control technology and ability to understand and invent things are all possibles. All knights tend to have at least one power. I think most of the new ones tend for more constructive powers, but I don't know if that is the Lady selecting them or something else."

"Why do you keep saying 'of course' about throughly non-obvious features of reality?" He shakes his head, "More importantly, what do you hope to get out of being an Oathknight? Are you doing this mostly to get the magic or mostly out of a feeling of social obligation or duty of some kind?"

"The entire situation follows a lot of narrative tropes that are easy to recognize? A lot of it looks like from an anime with magical girls that transform into super-heroes. Ah, I completely failed to explain the basic attributes of an Oathknight, it includes an alternate form called 'Armor' which allows you full access to your powers and looks generally like you, but young adult and donning an impractically elaborate armor that still lets you move at easy. In armored form, knights can summon a magical weapon and a shield. Old knights can get the ability to create a slowly expanding castle, but the new ones might get a super-powered pet. And wanting magical powers is the main reason, but I also would like to help people. Magic that helps people is like the best thing ever."

"That's a fascinating coincidence, I have no idea what to make of it. Is a castle useful in 2015? I mean you specified that it was magic, and it doesn't sound like you're defending against conventional assaults so the reasons why castles aren't effective against guided munitions probably isn't too relevant but I'm still kinda unclear what use a castle would be. Also, if you only have access to your full powers in this alternate form is there some non-aesthetic reason why you would ever exit it?"

"Besides keeping a secret identity? The form that you're not in recovers faster. Just changing in and out is revigoranting. Otherwise, not really."

"Huh, that's an interesting advantage. Why do you need a secret identity? Is it just a work-life balance thing or are Oathknights disliked by the official power structure? Also you didn't give me an answer about the castle."

"Not everyone wants the public life, some might dislike or fear their governments. Oathknights is not technically a job. And I am sure some are doing it because it fits the tropes. The power structure has mostly been confused about the knights. Castles are magical, they... do a space distortion thing that means you can put them wherever without damaging surrounding buildings. They can be hidden and you can learn how to influence some of their properties in useful ways, like making a room where healing is faster. Multiple knights can join castles together for a bigger one."