WARNING: This appendix contains sensitive material that may not be appropriate for younger readers.
The Triforce Wars
In writing a story like Triforce Wars, which involves time travel, paradoxes, and a whole lot of headcanon history, you have to work out a lot of information. What happens between known canon points? How do we get from stuff in the story to stuff in the games? What happens after the story?
If you may indulge me, this is some of the supplementary material I worked out in writing and planning this story.
The races of Hyrule
The Hylian people fare probably the best of the races of Hyrule. Between Triforce Wars and Ocarina of Time, very little changes for them, and the end result of the Hyrulean Civil War bolsters national pride in a rather big way - not only is their royal family now the leaders of all the races, but they don't have to compromise on their land or privilege. Throughout the years, however, the Hylian population slowly begins to dwindle - while there's always a strong Hylian population (including the Royal Family), their numbers are slowly replaced with Humans. As Hylians and Humans intermarry, it becomes increasingly rare to find pureblooded Hylians. By the time of Adventure of Link, the Hylian population is a minority, albeit a minority that still rules the country.
To contrast with the Hylians, the Sheikah fare rather badly. With the Royal Family in full knowledge of what Kula did to Zelda, it's unsurprising that some members of the family begin to harbour resentment towards the Sheikah, resulting in abuse and the population being taken advantage of. When the Great Betrayal takes place, at least half the population leaves Hyrule, no longer considering themselves Hyrulean. While others remain, they stay as an objectified people, with Shadow Guardians like Sheik frequently taken advantage of - being forced into wars, servitude, and other indignities.
By Ocarina, most of the Hyrulean Sheikah have either been slaughtered or have fled. During the reign of the Sheikah-friendly Zelda of Ocarina, some begin to return (it's from these Sheikah that Impaz is descended from). Once this population passes on, however, this leaves only the long-departed non-Hyrulean Sheikah, no longer bound to the Royal Family in any way.
After death, Sheikah have, for the most part, three alternatives. Some, like Sheik, become Shadow Guardians - instead of their souls able to move on, they are trapped in the River of the Dead. Their bodies are cremated - any remains of their old body would force their soul to return to that, even if it's a decaying husk. This is... understandably traumatic. The majority of Sheikah are able to move on, their bodies also cremated. A smaller population have their souls move on, but their bodies are not cremated - these become the ReDead, guardians of the Shadow Temple and of Kakariko Graveyard.
Some Sheikah have profoundly different fates. For those like Kula, sacrificed to protect the village, they continue to act protectively - Kula would become a ferryman on the River of the Dead, able to watch over his brother and the other Shadow Guardians between their lives.
The Shadow Guardian ritual that Sheik would have undergone on the battlefield would have involved Eldir slicing his and Sheik's hands open, and Eldir allowing his blood to drip into Sheik's wound. This permanently binds him to the Royal Family through his very blood, and the words Eldir would prompt Sheik to say would preserve his soul enough that it could be returned at any time. To bring back a Shadow Guardian, it requires the blood of the Royal Family to be spilled in the Shadow Temple - this ensures that the Sheikah won't be able to bring back their departed loved ones for their own purposes. The Royal Family member in question then has command over the Sheikah, although as Zelda demonstrates in Triforce Wars, this can be waived. They do, however, always maintain a bond to the Royal Family member who made them like that (so long as they are still alive).
Everyday life, training, being sworn in, and relationships
Everyday life for young Sheikah involves, predominantly, huge amounts of training. A typical day would involve a young Sheikah rising before dawn to bathe and dress, including face coverings - only immediate family is permitted to see a Sheikah's face (as well as those the Sheikah will later be sworn to, and lovers - this, however, isn't relevant to children). The young Sheikah then engages in chores before their parents or guardians rise, and they eat breakfast. After that, schooling takes place in the morning, and after a midday lunch, training in many different areas occurs. It isn't unusual for a young Sheikah to train in hand-to-hand combat, combat with weapons, the arts (particularly music), and many different types of magic. (As most Sheikah age, they begin to specialise in areas of their choice, although some, like Sheik, continue studying many things.) At sunset, a dinner is eaten with the family, and then the evening may be used for entertainment (particularly music).
For those who have come of age, the daily routine is only a little different - they would rise at sunrise, after the children have bathed, dressed, and performed chores, and eat a family breakfast together. Instead of schooling and training, adult Sheikah would undertake whatever work they have been trained in - many Sheikah, for instance, are craftsmen or make herbal remedies for both their own population and for others. At sunset, they rejoin their family for dinner.
The week before a Sheikah's thirteenth birthday, they undergo an intense series of tests - physicality, combat, magic, the arts, and many other areas. On their thirteenth birthday, their new post is announced - Sheik is one of the few to gain a prestigious position as a personal guardian to the prince. Other Sheikah, like Kula, go into artistic areas (although skilled in magic, he was selected as a dancer), while others take more menial positions if they score low enough. There is also a quota every year of Sheikah permitted to remain in the village, usually those who wish to start families or otherwise learn a trade to support their people. A Sheikah becomes an adult at thirteen, and may begin courtship then.
Those destined to take up positions with the Royal Family spend the next year under intense, rigorous training to help them achieve their full potential. On their fourteenth birthdays (the day a Hylian is considered an adult), they are sent to their new positions, and are expected to remain there until they are released (or they die).
In some cases, Sheikah who fall in love and who wish to do so may be released for fourteen years in order to raise a child, although once their child turns thirteen, they are expected to return to their duties. This doesn't mean that all lovers get fourteen years off - it's only heterosexual Sheikah couples who intend to start a family that get this.
The Sheikah view relationships very openly - there is little disapproval of homosexuality, polyamory, or even relationships with Hylians. Even incest is viewed as something to be mildly tolerated - the only truly taboo relationships amongst Sheikah are those involving children under thirteen, heterosexual incestuous relationships, heterosexual relationships with Hylians (as both can result in offspring), and intergenerational incestuous relationships (such as a Sheikah youth with their aunt or uncle). Large age differences between unrelated Sheikah are frowned on, but aren't disallowed.
Despite this openness amongst relationships, a Sheikah is still expected to have children with another Sheikah. Sheik's relationship with Link (a male Hylian) is nothing out of the ordinary, but he would later be expected to have children with a Sheikah girl. Sheikah-Hylian hybrids are strongly frowned upon, and any offspring from that union may find themselves outcast (along with their parents) - until events change much later on, Sheikah heavily believe in racial purity. It should be said, however, that some Sheikah outside of Hyrule's borders view Sheikah-Hylian or Sheikah-Human hybrids (or the rare Sheikah-Gerudo hybrid) with a little more tolerance.
Unbeknownst to Link, he is a major influence in how the Kokiri change and develop. Several millennia ago, a group of settlers descended to the land that'd become Hyrule, headed to the forest, and perished. Thus, they were unable to undergo the transformation the goddesses granted their brothers in the mountains and on the rivers. It takes several hundred years for life begin to take root again in the forest - with the sprouting of the Great Deku Tree, those little glimmers of lost souls are used as templates for a new type of life. Based on the abundant plants and using those base emotions of curiosity, fear, hunger, selfishness, the Great Deku tree creates a race of plant-based children.
When Link arrives a thousand years later, however, things begin to change. The Kokiri are humanoid, yes. But they don't resemble Hylian children - and the Great Deku Tree, as a guardian spirit, is able to learn from Link that one day he will be raised amongst them. Subtly, things begin to change - their leaf clothing begins to detach, their skin is less green-tinged. Slowly, they begin to look more human.
And once this is all over and they're no longer under the Great Deku Tree's influence, things, once again, begin to change. In the adult timeline, the Deku Tree Sprout begins to make them smaller, lighter, able to drift on the winds so that they could escape the incoming sea, and as he grows, they, too, begin to change into the Koroks. The child timeline, however has a different fate - with the Great Deku Tree already gone and with no replacement forthcoming, the Kokiri begin to devolve back to their plant-like state, eventually spreading wild throughout the hidden areas of the forests that would one day become Ordon and Faron. Eventually, they will disappear entirely, becoming slightly intelligent plants or bodiless plant spirits - some even become the fairies that once guarded them.
While the Hylians linger for a long time, the Gorons end up the most widespread. Able to survive anywhere that has rock, both before and after the events of Triforce Wars, they spread far and wide - in the adult timeline, they make it all the way to areas as far-flung as New Hyrule, as well as regions like Labrynna, Holodrom, and Termina. They remain a robust and proud race, and aid chosen heroes over a great many generations.
The Zora also spread far, although, restricted to clean water of a suitable temperature, they remain less robust and ubiquitous than the Gorons. Ultimately, it's time that erases the Zora - a lack of suitable waters, warfare, and simply being more delicate than other races erase them away. Other Zora survive by taking to the seas, the harsher conditions resulting in more aggressive and warlike societies - even their name changes to reflect this difference.
Ah, the Gerudo - the only race to fare worse than the Sheikah. The Gerudo have a blink-and-you-miss-it history in Hyrule proper - the society is originally founded by criminals and undesirables cast out to the deserts beyond Hyrule's borders. In such harsh environments, theft becomes a necessity to survive, and is later incorporated into their growing society. By the time of Triforce Wars, they are foreigners, and it's only around the time of the Hyrulean Civil War that their hands are integrated into Hyrule (under the leadership of Ganondorf, who has heard of the Triforce but is favouring a slower, more measured method to get it than all-out war - this is also motivated by the fact that he really does want what's best for his people, and what's best just happens to includes the invasion of Hyrule).
Their fates are quite different in the two timelines. In the child timeline, with Ganondorf executed/locked in the Twilight Realm, Zelda's xenophobic father begins a program of systematic execution for theft (regretfully common), banishment into the Twilight Realm (along with the Dark Interlopers from ten years earlier - while the Twili affiliation with the shadows comes from the Sheikah, their red hair comes from the Gerudo), and exile. Their fate in the adult timeline, by contrast, is actually happier - they take to the waters and become pirates instead of thieves, like their sisters in Termina.
While Humans (as a distinct race from 'humans', the general term given to Hylians, Sheikah, Gerudo, and Humans) don't appear in either Triforce Wars or in Ocarina, the later history of Hyrule features them prominantly. Originating from surrounding lands, like Ordona to Hyrule's southern and southeastern borders, a slow migration of Humans ends up trickling into Hyrule proper in the years after Ocarina.
Physically close to Hylians, save their rounded ears and decreased aptitude for magic, intermarriage is inevitable - while the two races are distinct by the time of Twilight Princess, by the time Zelda awakens, the two have mingled so much that 'Hylian' and 'Human' are distinct minorities. Most families would have mixed blood - including, to an extent, the Royal Family, although not so much that the Royal Family loses any physical traits of their Hylian ancestry. The Link and Zelda of the NES games (excluding, of course, the Zelda of Triforce Wars) are distinct because they are mostly pure-ish Hylians, something that is quite rare in the scheme of things.
The Hylians and the Sheikah
Relations between a guardian and their charge
The relationship between a member of the Royal Family and their charge is a strong one. The member the Sheikah is sworn to is one of the few they are permitted to bare their face to, and it is expected that they will serve for the entirety of their natural life (and, sometimes, afterwards as well).
A young prince or princess does not start with someone like Sheik or Naziya, however. A child of the Royal Family has something between a protector and a nanny - this is always a female Sheikah who uses the title 'Impa' (the Sheikah word for 'aunt'). This title continues to refer to a guardian of a prince or princess for centuries, even once the position is no longer held by Sheikah.
A Sheikah sworn to a member of the Royal Family must obey absolutely - the word of one they're bound to is tantamount to a magical contract. When Eldir ordered Sheik not to speak of his plans, Sheik would find himself physically unable to communicate it - if he tried to speak it, the words simply wouldn't come, and if he tried to write it, then he wouldn't be able to physically form the words. This is usually released by death, although some (like Eldir) think ahead and ensure the order holds beyond death, as well.
Relations in the castle and public
Sheikah are viewed as servants, no matter what position they hold. While many do hold menial positions (like the maid that Link encountered when he first woke in the castle), even those with high-up positions (guarding important nobles, or even guarding Kings and Queens) are considered to be answerable to Hylians. They're not, of course - the only true barriers are those of rank (a Hylian castle guard outranks a Sheikah stableboy, but a Sheikah castle guard will outrank a Hylian stableboy), and those between a master and their servant.
But the Hylians do hold this perception that the Sheikah are merely servants, and will attempt to order them about despite rank. The Sheikah is then able to retaliate (much to the chagrin of those doing the ordering) if their rank allows for it - most, however, will simply ignore the attempted order and go about their day.
This changes once Kula attacks Zelda - following this, any castle Sheikah becomes answerable to any castle Hylian, and it becomes extended so that any Sheikah becomes answerable to any Hylian following the Great Betrayal. This isn't reversed until the time of Zelda of Ocarina of Time.
By the time of the Hyrulean Civil War, the Sheikah are viewed as mistrustful shadow-dwellers with unspecified abilities, simultaneously to be feared and taken advantage of. This is largely why no one who learns of the Kakariko massacre protests greatly against it.
North Castle and Zelda's fate
North Castle, and the Hyrule it lies in, bears little resemblance to the Hyrule of Ocarina of Time. In this, it is explained as that Hyrule simply being a little-known external territory (until some calamity forces the population northwards in to this new land). While North Castle gains use once again, the tower that Zelda rests in remains protected.
This protection is particularly important for the adult portion of the timeline. When Hyrule is flooded, Zelda's chamber remains sealed against the water as well as the progress of time, allowing her to survive the calamity. The king's order for Hyrule to be flooded does not include her chamber, which is protected by other methods - it simply remains sealed at the bottom of the sea until either the sea is drained or someone gains the power to explore the sea floor.
Once Zelda awakens in the child timeline, she finds herself in a totally different land. It's also the cause for change amongst the Royal Family - the Zelda of LoZ is the last of the royal family line to hold the name 'Zelda'. Her own daughter gets a unique name, and her granddaughters do as well. With Zelda I no longer sleeping, the tradition of naming every royal daughter 'Zelda' is no longer relevant.
A 'brief' timeline
Dates measured as BG - before Ganondorf claims the Triforce - and AG - after Ganondorf claims the Triforce. Child portion of Ocarina of Time is year 0.
A note about the timeline: Yes, this is entirely headcanon! The dates for the actual events of Triforce Wars and Ocarina are locked in (for this particular timeline), but the rest are more malleable. I am using the assumption that Hyrule has twelve months (of different names, though), and that their new year falls at the end of December - the end of the month closest to winter solstice. This timeline does not include the majority of the handheld games - the Oracle games, Minish Cap, and the Four Swords games.
~2000 BG: The first settlers descend from the world of Skyloft. Finding the land that will one day become Hyrule uninhabitable, they retreat - some to the mountains, some to the lakes and rivers, where they travel on woven rafts and canoes. Another group travels into the forests and becomes lost. These settlers are adapted by the goddesses to their new environments - the mountain-dwellers become of stone, the river-dwellers become aquatic and able to survive beneath the surface, too.
~1600 BG: The next group of settlers descends. They find the land shadowy and dangerous as well, but this group decides to take to the shadows and shape them into their home.
~1500 BG: The adventures of Link I, the Hero of the Sky. The Skyward Sword is shaped into the Master Sword and becomes a symbol of the people. With the land below now cleared, more and more residents of Skyloft descend - the field-dwellers take the name of 'the Hylia people', while a group of outlaws and trouble-makers are forced out of the new land to the desert. Throughout this time, the Gorons and Zora begin to spread outwards, and those lost in the forest begin to gain glimmers of sentience. The shadow dwellers - the Sheikah - continue to roam the land, a nomadic population based on trade.
~800 BG: Now fully-fledged civilisations, the first official Hylian Royal Family is founded from a family that has been involved with the Hylia people from the start. Formal borders are drawn up - it excludes the desert but does include the mountains and rivers, although the Gorons and Zora have their own governments set up.
~600 BG: The nomadic Sheikah population begin to settle into Kakariko village. On good diplomatic relations with the Hylian Royal Family, it becomes a tradition for Sheikah boys to try out as protectors and guards of the Royal Family.
~550 BG: Eventually, Sheikah girls are permitted to try out as well. The system is finalised for how young Sheikah are selected.
454 BG: Prince Eldir is born.
453 BG: Twin boys are born in Kakariko village - Sahil and Kula.
452 BG: Princess Zelda is born.
451 BG: Naziya is born to a travelling family, who then settle into Kakariko Village.
439 BG: Sahil (now called Sheik) is sworn in as Eldir's protector on his fourteenth birthday.
Early October 434 BG: Link awakens in the past. Shortly after, Sheik is injured in a raid.
Early November 434 BG: Sheik invites Link to a Celebration in Kakariko Village.
Mid December 434 BG: Two groups go to the forest and the desert. Sheik is killed. Three days later, he is revived, and two days after that, he and Link return to the castle to find Zelda cursed. Kula is killed. They track Eldir to the desert and 'rescue' him the next day.
Late January 433 BG: The final battle. Sheik dies again, and Zelda is interred in North Castle. Link returns back to his own time.
~275 BG: A king of Hyrule, knowing of his ancestor's sister's fate and hating the Sheikah, starts a systematic pattern of abuse. This includes using them as disposable troops in a fierce set of battles, particularly the Shadow Guardians. Many Shadow Guardians are revived again and again to serve as front-line troops. Eventually, a leader of the Sheikah incites his people into rebellion - however, the leader is executed and the Sheikah given the choice to remain loyal to the Royal Family or to go into exile. The Sheikah population is split in half by the choice. Sheik chooses to stay loyal to the Royal Family to ensure that he will see Link again. The tear is added to the Sheikah Eye.
12 BG: The Hyrulean Civil War begins. A group of magic users are given the name of the 'Dark Interlopers' and begin to hatch a scheme to take the Triforce. Many Sheikah, tired of the abuse and of being taken advantage of, join up.
10 BG: To ensure that no more Sheikah are permitted to join the enemy, the entire Kakariko-dwelling population - men, women, children, and the elderly - are slaughtered by the Hylian Royal Army, on the orders of the king's adviser. The remaining Sheikah scatter to the borders. The only Sheikah left in Hyrule is Impa, the loyal guardian of the Queen and her infant daughter Zelda. The Hyrulean Civil war ends with the banishment of the Interlopers to the Twilight Realm. A wounded woman escapes into the forest with her newborn son and dies shortly thereafter. Hyrule is unified under the Hylian Royal Family, and the King of the Hylia People becomes the King of Hyrule. The desert is brought under jurisdiction of Hyrule for the first time, with their king, Ganondorf Dragmire, swearing fealty to the Hyrulean king. Impa, the last survivor of Kakariko, opens the village up to Hylian refugees from the war.
6 BG: The toddler Princess Zelda begins to have peculiar dreams - the start of her precognitive ability.
1 BG: Zelda's dreams become clearer and more intense, including recurring dreams of a darkness taking over Hyrule and a figure in green from the forest clearing it away.
Early summer 0 BG: The events of the child portion of Ocarina of Time take place. Zelda's soul is prompted into a deep sleep as Sheik is recalled from the River of the Dead to protect her. It remains Zelda's body, but it has now been shifted to resemble Sheik's, including his death wound. He remains ignorant of everything save his duties.
~3 AG: Zelda begins to stir in her and Sheik's shared mind. When she tells Sheik about the Hero of Time, he's assaulted of memories of his entire first life, including Link.
Early summer 7 AG: Link awakens, and the adult portion of Ocarina of Time takes place. Once Ganondorf has been sealed away, Zelda sends Link back in time.
~100 AG: Ganondorf begins to break his seal. Without a Hero, Hyrule is flooded.
~250 AG: The Hero of Winds defeats Ganondorf again.
~350 AG: The Hero of the Rails defeats Malladus.
Early summer 0 BG: Ganondorf is executed by the Ancient Sages (the original forms of the Sages of Ocarina of Time in their unawakened form) before he can claim the Triforce. However, as he's already claimed it in the future (paradoxes are involved), he still possesses it and strikes down one of the sages. He is sealed in the Twilight Realm instead.
Mid-summer 0 BG: Link departs Hyrule to travel to who-knows-where.
1 AG: After travelling, training, and regaining Epona, Link returns to the Lost Woods, only to find himself in the land of Termina. After defeating Majora, he stays in Termina for several years.
4 AG: Link returns to Hyrule, then leaves again to continue travelling.
8 AG: Link receives a summons from Zelda and returns to Hyrule. Zelda sends him back in time 442 years in order for time to remain consistent. A few hours (to her) and several months (to him) later, he returns. He and Zelda return to the Shadow Temple to say their goodbyes to Sheik properly, and Link departs Hyrule again.
~35 AG: Link dies in battle after defending a foreign city to the end, taking his enemy with him. Unable to rest, however, his soul wanders, taking the form of a skeletal warrior.
~250 AG: Link assists the Hero of Twilight in his training, allowing for him to defeat Ganondorf again.
~255 AG: Impaz, the last of the Hyrulean Sheikah, dies, breaking the lock on the River of the Dead. The Shadow Guardians there are released, and are able to go on. After saying goodbye to Kula, Sheik finds Link again. However, they don't move on to the next stage - instead, they are free to wander the ghostly realm.
~450 AG: The events of A Link to the Past take place, and the Master Sword is laid to rest.
~451 AG: The events of Link's Awakening take place (the Hero of Light awakens in Hyrule, the Goddesses intervening to keep their Hero alive).
~570 AG: The events of The Legend of Zelda take place.
~571 AG: The events of The Adventure of Link take place, and Zelda awakens in North Castle.
~660 AG: Zelda finally dies of old age, with Link and Sheik returning to escort her soul to the next stage.
And that's that! I hope you enjoyed this, well, giant info dump, and the story itself! Thank you for reading!