...he takes a deep breath and tries to put his thoughts in order.

The short answer is that he has a responsibility.

The long answer...

At home, he lives in a world-spanning empire called Eianvar. His grandfather used to rule it. When Korovai was a small child, Emperor Torvari looked at the empire's history - civil wars, wars of conquest, succession disputes, disastrous emperors - and decided that something needed to be done about it. Torvari spent a few years carefully thinking over how to restructure his government into something with more long-term stability and less reliance on the competence and moral character of a single individual, and just as he was about to put his plans in place, his son, Korovai's father, had him assassinated and took control of the empire. Korovai was six at the time.

Emperor Siurek is everything Torvari realized was wrong with the world-emperor concept. The civil war he began with Torvari's death was long and bloody, and the campaign to reconquer the outlying territories after that was shorter but bloodier, and now that he's firmly in power, all he wants to do is live a life of unparalleled luxury and torture people a lot. The only reason the empire isn't already well on its way to falling apart is Lady Reihar Nirue, who is competent, organized, and has the foresight to realize that she can't keep living a life of unparalleled luxury and torturing people a lot if the empire ceases to function.

And the only thing Korovai can do about all this is wait until some unforeseen accident claims his father's life, and hope that when that day comes he'll have some way of dealing with Nirue so he can fix the empire without her interference, and in the meantime make slow careful inroads into those parts of imperial administration which both Nirue and Siurek find boring, so he can at least make sure that some things are run by someone who is neither incompetent nor evil.

So now he is here. If he doesn't get the magic, he'll definitely die, and that will be the end of his ability to fix his world. If he does get the magic, he probably still won't be able to get home, not from a starting point of having no idea where to start - but it's possible in principle, so he will not allow himself to give up. He is not capable of giving up. He will do everything he can to get back to his world and make it a better place to the best of his ability, because as the only available Fareine who cares, he is his world's best shot at recovering from his father's disastrous reign without yet more civil wars. And while it's possible that something will happen to his father while he's away, by far the likeliest thing is that Siurek and Nirue will keep right on doing what they're doing until he comes back, however long it takes.

With that in mind, he will do his best to get the magic, and then do his best to go home, even if going home takes him a very, very, very long time. Because any less than that would be abandoning his people.

For a few seconds, there is no response.

Then the monument indicates that it finds this answer acceptable. It can resume teaching him about taieli now.

Okay.

Each atailora (taieli mage) begins with the ability to do magic at touch range. With practice, they can expand this to do magic to things farther and farther away, until the only constraint is their ability to specify a target object or location and know enough about it to successfully do magic to it.

There are six range levels, conventionally described as "touch", "arm's length", "stone's throw", "line of sight", "familiar", and "unlimited". These descriptions are approximate rather than strict, and especially as an atailora progresses between levels, they may find themselves slightly exceeding or slightly falling short of the level they are nominally at; but the levels are also discrete, so there's a noticeable jump between 'a little more than arm's length' and 'a little less than a stone's throw'. The levels are also cumulative: someone with line-of-sight range can work magic on an object they can touch but not see, and someone with familiarity range can work magic on an object they can see even if it is not personally familiar to them.

In addition to the basic ability to use the nine ainelin, each atailora also has a unique sensory/informational power that is suited to that person specifically. It is impossible to predict in advance what someone will get, but it always turns out to be something they appreciate and find useful and intuitive, even if they might have preferred something else. The power is called a fera, but a reasonable translation into Eivarne might be 'Sense'.

At which point he realizes that he speaks an entire new language.

This is bizarre.

He has learned languages before. Satni, Avashin, both dialects of Hialene, and a few from the outlying territories. It's hard work and it takes years to achieve reasonable fluency; it's been - not more than nine days, anyway, being educated by the monument interferes with his sense of the passage of time - and now he speaks Aiha, the language of the monument's creators, every bit as fluently as his native Eivarne.

It's a good thing the monument seems to be more or less benign because that's honestly kind of terrifying.

What happened to these people, anyway? Does the monument know? He can't help being curious.

The monument knows how it was built, and it remembers every evaluation it has ever made, and it remembers when its surroundings were sunlit and inhabited, and it remembers the end of both habitation and sunlight, and subsequently the end of evaluations.

As for the reasons... most things have finite lifespans. The monument very emphatically does not, but it was the work of a civilization-spanning effort that took years of coordination on an unprecedented scale. Here is a more detailed explanation of astrophysics, with reference to the law of entropy; see how all the stars eventually burn out, and the birth rate of new stars slows and slows and finally stops? It's possible to extend a star's lifespan or create alternatives with taieli, but the scope of the project required to sustain a civilization that way would have been on a level with the creation of the monument, and they weren't able to muster that kind of effort again.

...so he's on a deadline after all. A deadline of - billions of years, most likely, but he does not in fact have literally forever to get home, if his world works anything like this one, and it sounds like except for the magic it more or less does. Good to know.

Is it possible to create another monument? How difficult would it be? Can the monument teach him how?

Creating another monument: possible. Difficult. Much less difficult than creating this monument in the first place. This is the original, the template, the first and last; there have been others built in its image, but none were indestructible and so all, eventually, were destroyed. The monument system is intended to allow for arbitrary numbers of secondary monuments; it would have been highly inefficient for all the prospective atailoran on dozens of planets to have to come here and be evaluated one at a time over the course of nine days each.

The monument can teach him how to create more of it; would he like to learn?

Yes. Definitely.

(If he's going to prevent his world from dying one day he is going to need more than one atailora, and it might be prohibitively difficult to bring people back here. He has to know how to bring this magic elsewhere.)

In that case—

The monument draws him into a vision so complex that it completely displaces his ordinary senses. One atailora can build a monument, although it is difficult and time-consuming and requires care and precision. Here are the specifications. The geometry of the central platform must be exact, but it is possible to vary the other architectural details; the exterior of the monument matters not at all, he can carve it out of a mountainside surrounded by solid stone and it will still qualify; the ninefold symmetry of the structure is necessary, and here's the trick with rilte that allows you to reflect the structure to the necessary degree of precision...

And that's just the building. The magic that becomes a part of it draws on all nine ainelin. Beshenn to make it durable and guard it against tampering, ileyi to give it the ability to create things like air and the letters made of light that he saw earlier, poai so it can sustain the life of a prospective atailora while evaluating them, kiina so it can learn and understand - but not too much, because it would be a problem if a taieli monument became a person - and rilte in its memory and its adaptability, and tsaer in its discernment, and epru so it can keep its interior neat and tidy, and naharr to make its evaluations unpredictable and prevent people from trying to game the system, and soryo to bring it all together and coordinate the disparate pieces into a unified whole - and more and more layers of each aineli under that, serving more and more complex roles, coming together into a dizzyingly intricate artifact.

The monument system was created in order to unify the various methods of acquiring taieli into a single sensible reliable whole, when the ancient Aihanin discovered that inventing a new method for passing on the magic made previous methods less effective. The capacity to use taieli was once strictly heritable, and then thousands of people invented their own individual ways to give the magic to someone who wasn't born with it, and by the time they noticed something was wrong, the heritability factor no longer worked at all. So they brought everyone together and created this system: eternal, inviolate, impossible to supplant with a new method. And they made very sure that it would function for their purposes, and keep working forever, and they built in as much flexibility as they reasonably could, and they gave it criteria with which to make sure that new atailoran were not the sort of people who would wreck planets with naharr or turn cities into frozen dioramas with beshenn.

Normally the monument would not give away the secrets of its own construction to someone it was still evaluating, but it has known that it was going to give him the magic since before he asked. He is extremely qualified.

He absorbs all the information, pays careful attention - he needs to have this down, he needs to be able to do it without making any mistakes that would disqualify his attempted monuments and render them nonfunctional, this is important - and he's so caught up in memorizing the details that he almost misses that last remark completely.

It... makes sense, once he stops and thinks about it. He knows the monument's criteria now. An atailora must be the sort of person who will use magic responsibly and carefully and not maliciously. Most of the entire point of Korovai is being responsible and careful and not malicious. He's a very good fit.

Yes.

His nine days are up; the vision of how to create a monument took most of the rest of it.

He wonders what Sense he's going to get—and then he knows.

It's a Sense of self. His own mind and body, his own magic, the fading traces of the ongoing effect that the monument was using to suspend his biological needs while it evaluated him - and things he's touching, his clothes, the floor of the monument under his hand. It's strange and slightly unsettling, but he can see the use of it immediately. He is his own best tool, and with this Sense he can make sure he stays in good condition. He can improve himself - make himself immortal, probably, do away with his need for food and water and sleep, although he thinks he'll leave himself still able to eat and drink and nap in case those things turn out to be psychologically important.

It's going to be a tricky project and he has to get it done before he dies of thirst in here. He'd better get started.

His first priority is making sure he doesn't die while he's busy sorting everything else out.

He lays both hands flat on the floor of the monument and closes his eyes and explores its magic with his Sense. There's the part for sustaining his life - can he pull out a copy with rilte—? No, not quite, but he can spend a few hours studying its structure and then very carefully build himself a temporary version. Okay, there's his survival taken care of for the next few months at least. Now what?

Now he designs himself the perfect kind of immortality, that's what. The ability to die is a luxury he can no longer afford.

He needs to be not only immortal but also invincible, or at least proof against anything Reihar Nirue might try to do to him. But he also needs to avoid closing off potential avenues for improvement. He should be able to modify himself, but he should be the only thing that can - except that if he takes that principle too literally, he'll end up with all his external senses cut off because outside information would cause changes in his mind, or something similarly stupid. Careful, careful, careful.

A few hours' practice with rilte and ileyi gets him to the point where he can reliably supply himself with pen and paper. He starts making notes. The monument didn't do it, but someone else could - he needs to be immune to magical mind control, and he should probably also make his mind impenetrable to outside inspection - but for cases like communicating with the monument, he should probably be able to share his thoughts deliberately...

And on and on, through hundreds of different ideas for what should and should not be allowed to happen to him. Not only should he not be able to die, he should also not be able to become trapped. That's a hard problem, though, and probably relates to interworld transportation; he'll save it for after he has his basic immortality worked out. He should be able to eat and drink and sleep and breathe and so on, but not require any of those things in order to remain comfortable and functional. He should not be susceptible to aging, or to illness or injury or miscellaneous deterioration.

It may be tempting to explore potential improvements - make himself think faster, that sort of thing - but he should focus on the necessities of basic immortality first, and experiment with more daring self-modifications afterward, slowly. He has time; he does not have a spare Korovai if something happens to the first one.

...he could create a spare Korovai.

But that would be a significant undertaking, and could itself potentially go wrong in damaging ways, and he still needs to get his basic immortality out of the way before he starts in on other improvements.

It comes as a considerable surprise to him when he looks up from his notes and realizes that he is hungry. He's been distantly aware of the passage of time, but clearly not paying it enough attention if three months could go by while he was distracted.

Does he have everything he needs?

Not quite. He spends a few minutes reapplying the temporary fix, and then, no longer distracted by hunger, dives back into his notes. Three months later when the ward wears off again, he has his basic immortality designed and ready to implement.

Kiina to strongly reinforce his tendency to be himself. Beshenn and soryo for endurance and stability. Ileyi for inexhaustible energy. Poai to handle the biological side. Rilte for small improvements to how it all works. Kiina and beshenn again, and a touch of tsaer, to emphatically ensure that he is the only person who will ever be able to alter any of this.

There. Done.

Now to work on getting home.

Getting home... is going to be a problem.

The best idea he comes up with, after a week of writing on yet more paper, is to create any kind of transportation device at all and then keep iterating on it with rilte until he has something that works. He's not going to use naharr for this. Caution over speed, always. But if he does it that way, it seems unlikely that he will be able to aim. In which case he could be wandering for a while. In which case he had better find a way to consolidate all these notes into a form he can carry around conveniently.

Giving himself a perfect memory is slightly tempting, but on the principle of conservatism in self-modification, he instead gives himself a less deeply integrated ability to take, store, organize, and review private mental notes in arbitrary quantities. And then he rereads all his paper notes and puts them away in mental storage and clears away the physical notes with epru.

Magical transportation of any kind... ileyi can affect motion, let's start there...

Time goes on without him. It doesn't matter. The only thing he can do is keep working. He carefully crafts a flying boat, and then refines it into a teleporting boat, and then refines it further and splits off several variants and works on all of them until he has something that he's pretty sure can travel between worlds.

There's only one feasible way to test that, of course.

He tests easier things first. Reviews his immortality, implements a few small improvements, gets in his teleporting boat and voyages across this empty universe. There isn't even another planet available, but he can go assorted distances away from the monument and then return. It works perfectly every time insofar as he can tell. He tests its refusal to intersect with solid objects: it does indeed very much refuse to do that.

He takes the time to give himself a streamlined version of the monument's conceptual communication ability, because unless he gets home on the first try he's not going to speak the local language. He double-checks that he is definitely proof against anything Nirue could feasibly do to him, even if she had a god in her pocket.

And then he leaves.