This theory is concerning the conditions for a soul to be chosen by the Wheel as a Hero of the Horn, the conditions for a person to be a HotH.

The most explicit information about that in the books is the scene in Falme, when Artur Hawkwings said to Hurin:

"'It takes more than bravery to bind a man to the Horn.' Artur Hawkwing's voice was deep and carrying, a voice used to giving commands.

.....

Artur Hawkwing clapped the sniffer on the shoulder. 'Sometimes the Wheel adds to our number, friend. Perhaps you will find yourself among us, one day.' Hurin sat up as if he had been offered a crown." (Great Hunt, Ch. 47)

As I know, it's never said, what exactly is that "more" then bravery required. The only positive thing to say is, that this "more" must be the quality, needed by the Wheel for to use the Hero's soul for It's self-correction purposes. But something about the requirements for becoming a Hero could be given even here. For, when it is said "more then X is needed", most often it means: "it's needed X and also Y".

Possible meaning of the expression "more than bravery is needed" could also be something like "you may think that to be Hero is to do acts of bravery, but it is something different and it is something more valuable then "bravery". In an interview RJ said, that a Hero is not allway somebody galooping to rescue, sometimes a Hero is needed for something quite different from adventurous battle-scenes. But the fact that these bound to the Horn souls are known exactly as "Heroes", that by the call of the Horn all they (except the ones who are incarnated in the moment) come in the form of mounted warriors and when they come they're expected to fight, all that makes me to believe, that the common-sense idea of the heroic is essential characteristic of every Hero of the Horn. HotH may not allways act as what most people will understand under "Hero", sometimes it would be not the purpose for a Hero to be spun out in the world, but all the Heroes, at least in some aspects of their existence, have something to do with what is commonly understood under "Hero" and that in the most stereotype form of it of a galooping armed person who can do impressive rescuing deeds.

Maybe this archetypic "heroic" image is only one of the forms that the HotH can have by circumstances, and by other circumstances they will express their special quality in another form. Maybe the real HotH quality is something only similar to commonly understood heroism, but something more subtle and developed. Maybe the "hero" archetype is only a manner of formal appearance of what the real HotH is. Or maybe the galooping Hero archetype is something of minor importance about the HotH and something completely different is the primary. Too many options are open. But in all cases "bravery" is part of what HotH actually is, and it's the only explicitely known to us part, and it's the only thing we have to start with when theorizing about HotH.

Now few questions can be risen: Why the Wheel needs exactly "heroes" as corrective mechanisms (including non-channelers in that channeling world)? Why they are known to the wide public as exactly the ideal image of an adventurer Hero? Why "bravery" is in the picture, the "bravery" that can be connected more with the potential to disbalance things even if the deed is grandious rescue (why not rather leaders, negotiators, tradition-keepers, guardians or other form of more connected with preservation of a balance figures?)? What kind of "bravery" is needed for a HotH? So what can the "bravery" in sense of what is commonly understood under the deeds of a "heroic" adventurous character, what in that quality can be usefull for a so large-scaled and complex entity like the Wheel?

One of the first answers coming to mind would that the Pattern will need rescue-heroes to solve difficult situation for exactly the same reason an ordinary story will need such a hero. IMO this is not a good explanation. It's true that brave persons would be useful for specific task, but the glory and the seen to everybody intiative (the "bravery") is completely unneeded for the Pattern. The unvisible background agents would do Pattern's work much more effectively. A political manipulator or a low profiled leader of the sort Aleis or Lini would do much more for correcting actions of the scale useful for the Wheel then any singular imressive rescue-deeds. These silent agents would do better work for the Wheel, because they will make deeper changes, changes in the minds and habits of many people, they will correct the reasons and not only certain surface effects of the disbalancing processes that the Wheel wants to change. But there are no silent world-changers among the Heroes coming to Falme, all of them are notorious foreground-deeds makers. There must be another reason for this kind of persons to be used by the Wheel. What then? A couple of aspects of the bravery-hero idea can give an answer:

1. One thing in the vulgar Hero-concept that can be connected with the most serious and metaphysically deep reasons of the Wheel, is the fact that the "Hero" is somebody most deeply impressing large masses of people, a figure that inspires the imagination of the world's population. A Hero figure from the gleeman's tales is a figure thousands of young (and some not so young) ones dream to be. Wiser people, who want not the risks and misfortune, an ideal-hero manner of actions will cause one to suffer, and so will equate "hero" to "fool", even these people would feel sympathy to heroic characters and will estimate it as a sort of an ideal - maybe practical unreachable, but an ideal. So the gleeman-tale-Heroes control the form of what people usually dream about, what they admire. Actually we see that gleemen change the actual deeds of the Heroes, so that e.g. Birgitte cannot recognize herself in the stories about herself. This means, the people have some expectations what to admire, and they edit the historical Hero deeds according to these ideals. I.e. people's dreams are prerequisites to the real Hero's life, the real Hero only fits into the archetype already present. So why the real living Hero is needed? The reason is that without the detailed Hero examples, the dreams of people are too vague, too undefined. The example Hero is needed to give to the dream a realistic form and all the details required for a complete image. Also a vivid image of a hero will make the archetype realistic-looking, people will easier think that such heroism CAN find it's place in the reality, including maybe their own reality... And it is common for archetypes and dreams, that even secondary details assotiated to them, modify their meaning a while or add something to this meaning. The vague archetype can have many options to realize itself, but when the archetype is assotiated with a detailed figure, this options are precised and reduced. There are still different options to interprete such figure, but compared to the vague archetype they are significantly less, and they are significantly shifted also. Assotiating an archetype with a definite form changes the functoining of the archetype in the human minds, who adopt this assotiation. The exact form a person assotiates with divine creatures, ideals of beauty, ideals of rulers and ideals of adventurous deeds determinate a lot of aspects of the person's reaction to broad range of social situations and ideal concepts and it reflects in many ways one's very personality. So a living Hero can give a form to an archetype, and the Pattern will definitely have lot of use of such deep and large-scaled influence. Historical living Heroes are not necessary needed for that purpose, a good fiction book can create as good example of a Hero's archetype as a living hero. But if the Pattern wants to set the form it wants, it would be easier for it to spun out a living hero, then to control a gleeman or other storyteller. Because storytelles are inspired about the details from other stories already existing, while the living Heroes are the ones whos actions inspire story-telling.

Weird Harold has a theory, that the sole human dreams and admiration are what actually creates a Hero's bond to the Wheel, that it's the reason for the Heroes to reside in TAR, and that the appearance of Heroes in TAR has nothing to do with the real appearance of living heroes but is the construct of a mass of storytellers and listeners in their dreams. It's too radical a theory, it cannot explain the binding of a particular soul as a hero and it cannot explain the precise details in Hero's TAR-appearance, but it has something true in it. The HotH have too much of the form of human imagination in them, they have too much of the form of an ideal. And HotH has too much connection to glory. I don't believe that this post-mortal glory is what makes the HotH, but I believe that it is one of the things required for a HotH to become such. It is not the mass of human dreams that binds the Hero to the wheel, but the Wheel calculated the mass of dreams it would need and choses the proper soul to play the role of the Hero and to give flesh to the reqiured archetype. The glory of the Hero through the dreams of humans strenghtens back the bond of the HotH to the Wheel.

This could have implication on why the HotH have the precepts to not interfere into the life of the living ones: if a TAR HotH does so, he/she declines a little bit from the figure strenghtened by the people's dreams. Birgitte does so, her bond to the Wheel temporary weakened, and that gave Moghedien the opportunity to rip her out...

2. Another thing about bravery could be a particular philosophical aspect of the virtue to be brave. To have this virtue is to be able to do what must be done (in case you know what it is, of course) when the circumstances press you to make an "wise" compromise. The lack of this virtue - the vice of cowardness, is when one knows what must be done and agrees that it is the right, but some circumstances makes the coward to act otherwise, to act not the way he/she believes it's right, but the way he/she's forced to do. A brave one would do what must be done, whatever happens. The usefullness of this virtue for Pattern's self-correcting mechanism is this independence of the Hero's actions from the pressure of circumstances: the Hero is one, who is reliable against circumstances pressure and would act energically and resolutely according to predeterminated principle. The Wheel uses Heroes when the trend of the world's historical process goes in a wrong direction: i.e. when the mass of the circumstances push all the singular threads into the wrong direction. For to do something against this case the Wheel has to use a thread especially resistent to the violence of the circumstances, a thread who will remain on balanced stands when all persons are influenced to change their stands.

Here is an advantage of "Heroes" before diplomates and other flexible world-changers. Wise and sensitive approach to the problems is connected to the tendency to make comromises, to follow the general trend of events: laissez faire, laissez passer. The Wheel have problems exactly when the dominating mass of events pushes in a wrong direction, so the wise diplomate would act in the same direction and would reflect in the actions and reactions the wrong principle of history. The Hero would be straithforward and unceremonious and so would be more independent of the wrong trends.

There are lot of stubborn people, who would be independent of the circumstances just because they are unsensitive. They will do what they know, but will not react in any manner to the real nature of the circumstances, and so their reactions would be inadequate and ineffective. Such inadequate actions would cause inpredictable consequences form the situations, but they would be predictable and manipulable by another people and so such people would rather increase the chaos and the wrong trends and so would be not usefull for the Wheel. The ideal solution would be a brave person, who adequately understands the situation and can effectively counteract, but would nevertheless not bend before the pressure of the circumstances. A combination of high sensitivity and high straightforwardness is needed. I guess persons with such virtue would be rare and the Wheel will need to carefully seek for them and stores them for use on demand. The Wheel would chose for it's purposes a soul that developes such attitude. Such virtue would also be expressed as heroic virtue, because the doing what must be done while understanding the complete degree of the danger requires greater degree of courage, and having the compormiseless attitude against such situations will make the hero more succeptible to stuck in dangerous deeds. They would appear a degree more brave then common bravery. Maybe that could mean "more than bravery".

Another trait of Hero's virtue would be faithfullness to some principles that are somehow connected to ballance preserving. Such virtue would be a sense of justice for example.

More about virtues: they are usually more difficult to live with then with vices, especially the virtues assotiated to Heroes. We know that the Wheel keeps a ballance between good and evil. For regarding virtues there would be rather a disbalance against evil, maybe the Wheel would arificially interfere to import more virtues of some more difficult categories in the Heroes spun out. That could be additional purpose of using gleeman-tale-like heroes.

3. Another thing about bravery would be the effect of an extraordinary heroic deed on the structure of Pattern. A heroical deed must be 1. rare, extraordinary (else nobody will consider it to be a heroic), but 2. not extraordinary due to excentricity, but extraordinary fitting into the situation, extraordinary in, so to say it, a healthy manner; 3. it has to be very effective, it has to solve a heap of processes with a single strike; 4. it has to restore some balance; 5. it has also to be a very intensive and energic action requiring immense efforts (easy success is not qualified as heroic, aven if very impressive) and endurance. How would these deed specifics look like in the threads of the Pattern? The Pattern is the way the threads of particualr lives and events are interwoven between each other in the common world's situation. Decisive in the pattern would be the mass of threads and the mass of events, and it usually makes the people's lives to follow the usual routine, the Pattern usually doesn't allow people to decline too much from the average set of human actions. So (1) an extraordinary deed would look unusual in the mass of the Pattern, it is something to attract the attention. The Pattern allows lot of various forms of behavior: different cultures, different social rank, different occasions. So the Pattern is tolerate to deviations from "normality, it just stores them into manners of behavior. It maintains variety of life-forms without a clearly distinguishable norm for what is "normal" and "healthy". The Wheel maintains rather a cultural relativism. While it is characteristical for the deeds known as heroical, that looking at them persons with different presupposition have common respect about them and become more definite criteria about right and wrong, Hero's deed becomes some kind of temporary norm, an evidence... So, (2) that it an exceptional form for the Pattern, and going against the common rule, it (4) maintains a ballance, i.e. an explicite task for the Wheel. Also, (3) more efforts looks like living for few hours more then years of easy life. Maybe (5) for a thread it would look also more intensive, more outrageous, equating in importance a greater volume of pattern material. Briefly a heroical deed would be something very specific in the metaphysical nature of the thread, that would have more "weight" than much greater mass of other thread-material. That would attract the "attention" of the Wheel much more easier than other deeds and threads.

So even if people living more silent life have the appropriate qualities for to fulfil the Wheel's special tasks, the Wheel would rather choose ones, who did heroic deeds, for they would be easier to pick up then the others. It must be not an accidental deed, for to be useful a candidate for HotH must be able to act correspondingly whenever he stucks in a situation. But among the persons with such an ability Hero will become the one who by some other reason (maybe accident) becomes into situation and does a heroic deed. So maybe there are many good men like Hurin in Borderlands, but exactly Hurin is there at Falme and after them exacly he has to bring the news to Shienar, and that makes him into the center of the events and he has chance to express his ability to react like a HotH would, and so he has the chance to become a new HotH.

...

Summarizing, the Wheel needs for the HotH class of autocorrections the following prerequisites: 1. Accepting of the correction by the minds of the population and guaranteeing of support to the correction by people: This is fulfilled when the HotH fits into an archetype. 2. Reliability as a tool of the Pattern and ability to have the influence whatever happens (for to fight the unhealthy historical trends, that would shift the norms and principles of the balance and therefore need independent principle to restore the balance): This is fulfilled by finding a soul with heroic type of virtues. 3. Wheel as a non-sentient mechanism, rather a computer-like entity, has to find the needed soul and to start the process of binding the Hero to the Wheel based on it's inner mechanisms. So the Wheel needs it's own naturaly privileged components for to identify and trigger the Hero-binding process. These starting points are the heroic deeds, that make the souls to HotH.