AN-Hey! Welcome all to my very first Kingdom Hearts fanfiction ever! I'm pretty excited about this, mostly since its sort of going to be a nice break from my GF/SU mega crossover Universe Falls, and because well... I love KH! I'm sort of a new fan, having only gotten into the series a little over a year ago, but I fell hard and fast for it, and when KH3 came out a few weeks ago, I played it in two days and LOVED it! So, you might be wondering what exactly this fic here is then. Well right off the bat its sort of an... AU of sorts of Kingdom Hearts 3. Don't get me wrong, like I said I LOVED KH3, but I kinda wanted to do my own spin on the story, basing things off of an old idea I had before 3 even came out, and now that it has come out, using 3's general structure as sort of a jumping off point to go from. So as a result, this fic will kind of take some parts of KH3 and will kind of novelize them in a way, but make no mistake, there is an original story to be told here, and its one that I'm VERY excited to share with you all!

Now for some more specifics (sorry for making this author's note so long! I just wanna make sure all my bases are covered!) Keys to the Kingdom is supposed to be set in place of 3, which is why I said its a bit of an AU fic. As a result, it'll have some of the same worlds from 3, but not all of them (the worlds that aren't making the cut for this fic from 3 are pretty much only Pirates of the Carribean (mostly cause I wasn't the biggest fan of that world in the actual game) and Monsters Inc (which I DID really love in the game, but it really doesn't fit in my plotline tbh. So instead, I'm going to have a BUNCH of other worlds that weren't included in 3, some from past KH games, some not, just to spice things up and help the plot. So, just to make things easier, I'd recommend being at least somewhat familiar with all these Disney properties before diving into this fic: Hercules, Toy Story, Up, Moana, Big Hero 6, Atlantis: The Lost Empire, Tangled, Coco, Cinderella, Princess and the Frog, Ducktales 2017, Aladdin (specifically Aladdin and the King of Thieves), Gravity Falls, Lilo and Stitch, Frozen, and Winnie the Pooh. Not sayin much more about what's gonna happen involving each of those properties, but basically, that's a taste of what's to come to get you excited ;) (also let it be known that I'm a HUGE Disney fan just as much as I'm a KH fan, so this is basically a labor of love for both!)

Next, some other things you should know: this fic is rated T for a reason. Things are... gonna get kinda dark later on down the line (though don't worry, my aim is to try and include as much KH charm in here as possible!), and that'll involve stuff like some minor blood and violence and such, as well as some pretty psychologically heavy moments. This fic WILL be a bit of an angstfest, so if that's not your thing, well... the door's right over there. Also, the main ships in this fic are gonna be as follows: Sora/Kairi, Roxas/Xion, Aqua/Terra, Vanitas/Naminé (might sound a bit odd, but just hear me out on it, I got a plan to make it work), and of course the usual Disney ships from each respective property.

And... that's all I have to really say to cap off this stupidly long author's note! Again, I'm SUPER excited about this fic (I have a lot of it planned out already!) and while it is gonna be a bit on the long side (probably 70ish chapters, just sayin) I hope you all stick around and join me on this wild ride! And so... without any further ado... Here it is! Enjoy!

Keys to the Kingdom

Prologue: The Thirteen Keys

Long, long ago, all the worlds were still one. One day, this would be called the Age of Fairy Tales.

The massive clock tower rose high above the sprawl of homes and shops that made up Daybreak Town, casting shadows upon its mostly resting residents as the sun only barely began to peak over the distant hills. In these early hours of the morning, the city was quiet and calm, the only sound echoing through the cobblestone roads and alleyways being that of the ever-swinging pendulum of the monumental clock resting in the heart of the town itself. However, on this particular morning, the sounds of five sets of footsteps could also be heard approaching that very tower, their wondering whispers soon joining in as they congregated together before the imposing structure, confusion and curiosity hanging over all five of the young Keyblade wielders like a shroud.

"Wait… you mean the Master summoned all of you here too?"

"Yes, though… he didn't give a reason why other than that it was 'extremely important'."

"He said that to me too… I wonder what it could be?"

"Whatever it is, we should listen well to him. Its said that his eye can gaze far into the future after all."

"Well, if that's the case, then I guess they don't call him the Master of Masters for nothing, huh?"

"Speaking of which, there he is!"

The other wielders turned their gaze to where youngest among them was pointing, up towards the center of the clock tower before them. There, a lone figure stood before the smoothly-swinging pendulum, clad in a pitch black hood and cloak that obscured his features as he looked down at the group far below. He said nothing, his hands held calmly behind his back as he simply turned and walked off, heading back inside the tower itself and offering the five wielders the unspoken invitation to do the same.

And though they still hadn't the faintest idea as to why they were there, the ever-dutiful group nodded amongst themselves, eager to hear whatever it was their Master had to say.

"Hey, hey! There's my five apprentices of the hour!" the Master of Masters greeted cordially as the five youths entered his chamber. "Ira, Aced, Invi, Gula, and… Ava!" He pointed at each of them as he essentially called roll. "Oh, and let's not forget early-bird Luxu over here." The Master nodded back at his sixth apprentice, clad similarly to him as he stood in the shadows of the room, offering a terse, yet silent nod to his fellow apprentices and little else. "You're all right on time. Sorry to call you all here so early," the Master continued. "But we have a lot to talk about, so you might as well get comfy."

The Master nodded over to the nearby table, prompting his apprentices to take a seat. Even still, it wasn't long before one of them, namely Aced, spoke up to pose the question that was on all of their minds. "Master, if I may ask… what is that you've called us all here for?"

"Ah, always ready to get right to the point, aren't you, Aced?" the Master asked knowingly. "Well then, I guess I won't keep you all in suspense. See, lately I've been busy doing some… digging, so to speak."

"Digging?" Ava asked, confused. "About what?"

"About the future, of course," the Master said, walking around the table casually. "We have a pretty nice setup here, as you all know, with all of us Keyblade wielders keeping the worlds safe from darkness and whatnot. But… things aren't gonna stay like this forever."

"What do you mean?" Invi inquired, a hint of worry in her tone.

"What I mean is that change is coming," the Master turned away from the group rather mysteriously. "Whether we like it or not. And that change is gonna leave nothing the same as what it once was. So I decided that we're better of safe than sorry and by preparing for it rather than panicking over it, which is why you all are here."

The wielders all looked to each other, still confused by the Master's vague implications as a whole. What did he mean that change was coming? What kind of change and on what scale? And if indeed it was a change for the worst as most of them had already started to fear, then what could possibly be done to prevent it?

It seemed as though the Master had read their worrisome thoughts as he turned back to his desk, picking up a stack of thick, stately books that he began to pass around the table. All five of the books were seemingly exactly the same, freshly-printed tomes with elegant silver engravings upon smooth blue covers. Needless to say that all five of the wielders were quite intrigued by these volumes as they began to leaf through them, spotting entries on Keyblades, darkness, and more.

"Master, what is this?" Ira asked with a focused frown.

"That…" the Master pointed to one of the books lying on the table. "Is the Book of Prophecies. Wrote it myself, so you can trust me when I say it's a pretty good read. Basically, it lays out everything you need to know about what's gonna happen, which, in turn will help you get everyone ready for it."

"Um… how are we supposed to do that, exactly?" Gulu asked as he shut his copy of the book.

"By taking charge of things around here!" the Master proclaimed with apt vigor. "That's why, from here on out, none of you will be Keyblade Masters anymore-"

"What?!" Aced exclaimed, appalled by such a claim. "B-but Master, we… we all passed our Mark of Mastery exams years ago! How could you just take our titles away from us like this?!"

"Ah, you didn't let me finish," the Master shook his finger disapprovingly. "You aren't going to be Keyblade Masters because you're all getting a promotion! Today, I'm upgrading all five of you from Masters to Foretellers."

"Foretellers?" Ava asked, curious.

"Yep! It's a pretty snazzy title if I do say so myself," the Master said, hands on his hips. "Each of you are going to go out there and recruit groups—or "Unions" of Keyblade wielders to train and teach, just like I did for all of you. Then you'll each send your Unions out to fight Heartless, ya know, those pesky creatures of darkness I warned you about? And from those Heartless, your Unions will gather light, which in turn, will help protect you from the darkness. So you see, it all comes full circle. Makes sense, right?"

"I suppose so…" Ira mused thoughtfully. "But Master, why chose the five of us for such an important task?"

"Why not you five?" the Master shrugged. "After all, I did train you myself. Unless… unless you think I wasn't a good enough teacher…?"

"N-no!" Ira exclaimed, flustered. "No, that's not at all what I was trying to say, Master! You've taught us incredibly well, of course!"

"Glad to hear it," the Master said mirthfully as he retrieved something else from his desk: a group of beautifully made, exceptionally intricate masks. "Now, don't think I'm spoiling you all, but I've got even more presents to hand out. Ira, why don't we start with you?" He presented his eldest apprentice with a grand unicorn mask with a graceful mane flowing out of it. "Here you go, the mask of the unicorn. Designates you as the leader of the Union Unicornis. As reliable as you are, I know you won't let me down."

"T-thank you, Master," Ira nodded dutifully as he accepted his new mask and role, knowing well the importance of living up to the Master's expectations.

"And for you, the fearless Aced," the Master approached his physically strongest apprentice. "The mask of the bear and the Union Ursus. Go out there and gather up some strong wielders to stand by your side for me, got it?"

"O-of course I do, Master," Aced said with a hint of pride for his new position in his tone. "I won't disappoint you."

"Hm… we'll see," the Master retorted vaguely, leaving Aced in a bit of confusion as he continued onto his next apprentice. "Now, Invi, as upright and virtuous as you are, you get the mask of the snake and the Union Anguis. I have no doubts that you'll lead them well."

"I… I shall do my very best," Invi said, forcing her voice to be stern as she accepted the great task before her.

"Gula!" the Master passed off the next mask to his second youngest apprentice. "Coolheaded and calm; I always liked that about you. Which is why you get the mask of the leopard and the Union Leopardus to call your own."

"I… understand, Master," Gula said evenly as he took his mask and all it entailed.

"And last but not least, Ava," the Master stopped at his last apprentice. "Young, pure-hearted, and kind. Just what we need to balance this group out. So, for you, I have the mask of the fox and the Union Vulpes. I have a feeling you'll lead them to the light with no problem."

Ava was silent for a moment as she stared down at the mask in her hands, awestruck at the heavy responsibility that now rested on her shoulders, even despite her youth. Still, in the end she nodded, confirming and hoping all at the same time that she could carry it out to the best of her abilities. "Yes, Master," she said with a deep breath of resolve. "I'll try—no. I will."

"You got it," the Master said, offering her a playful pat on the head before he moved to stand before the entire group once more. "Now, you're all caught up to speed. Don't worry, I'm still gonna be around to answer any questions you might have—for a while anyway—but for now, there's still one more thing we need to talk about. And it's… a big thing. A very big thing." The Master's usually playful tone turned serious as he paused for a moment, letting silence hang throughout the chamber. All of the newly deemed Foretellers leaned forward, and even Luxu perked up, curious to hear whatever it was the Master intended on revealing next.

"What I'm about to tell you doesn't leave this room," he began, his tone surprisingly hard and cold. "At least not until the right time has arrived. Each of you know that every world is connected by one great light, one heart that binds everything and everyone that lives, that ever has lived and ever will live together: Kingdom Hearts."

As the Master's last words echoed throughout the chamber, an air of reverence fell upon the Foretellers, all of them paying their silent respect to the source of light within their world. Kingdom Hearts was seen largely as a thing of legend by most, but the Master's research had confirmed to them that it was indeed real and was indeed the very thing that connected everything in existence, just as he had said.

"There's no doubt Kingdom Hearts is going to play a role in what's to come," the Master continued almost ominously. "Which is why all of you need to know this: the door to Kingdom Hearts can indeed be summoned by its counterpart, the weapon after which all Keyblades in existence are made in the image of: the X-blade. I've studied that exact X-blade for years, and I used that research to pull each of your Keyblades out of your own hearts, but… none of them are the same as the real deal. All of you already know this, but what I'm about to tell you is something that almost nobody knows."

Once again, the Master paused, leaving all six of his apprentices in almost breathless suspense until he finally unveiled this great secret to them in a tone so rigid and emotionless that it barely even sounded like the Master at all. "Even if someone does use the X-blade to summon Kingdom Hearts, that's all they'll do. Its true power, its complete essence, is something that can never be contained or controlled by anyone. Unless… that someone were to gather the thirteen Keys to the Kingdom."

As captivated as they were by the Master's lecture, most of the Foretellers barely even thought to speak up to interrupt him. However, as the Master let his words linger on the almost suffocating silent air once again, Ira decided to work up the nerve to venture the question each of them wanted to ask. "The… Keys to the Kingdom, Master?"

"Yep," the Master nodded, his tone a bit lighter than before but still just as serious. "Thirteen special Keyblades forged by the essence of Kingdom Hearts itself. They're scattered across a bunch of different worlds and hidden extremely well, to the point that looking for them is basically a fool's errand in and of itself. But… without them… well, anyone looking to take over Kingdom Hearts for themselves is bound to be real disappointed, let's just say that."

"W-well, that's a good thing, isn't it?" Ava spoke up somewhat apprehensively. "That means that if someone with a heart filled with darkness tries to claim Kingdom Hearts as their own, then they won't be able to… right?"

"Eh, maybe, maybe not," the Master shrugged. "I guess it all depends on whether or not the Keys stay hidden or not. But… I have a feeling that nobody's even gonna go looking for them for quite some time, so you shouldn't have anything to worry about on that front. Just as long as we keep this a secret between the six of us."

Without hesitation, the Foretellers nodded their confirmation that they would hold this prophecy to the upmost secrecy for the sake of protecting both Kingdom Hearts and the world itself. In fact, the only one of their number who didn't make this same silent, solemn vow was Luxu, who simply turned to leave the room without another word to act upon the careful instructions his Master had given him, as odd yet integral as they might have been.

"Now, I want you all to forget about all of this Key nonsense for now," the Master said with a passive wave of his hand. "Its not really that important for any of you to think too much about anyway. After all, you five each have much bigger roles ahead of you that we need to discuss. So… listen up!"

From there, the newly-named Foretellers spent the rest of the day heeding every word their Master had to say about their new positions with careful scrutiny. After all, as far as they were aware, the change that was on the horizon needed to be properly prepared for, regardless of what that change exactly was. However, when the five eventually did discover exactly what that change would entail, they were all quick to realize just how important the burden that rested upon each of their shoulders actually was.

For in time, the Master of Masters disappeared, leaving the fate of the worlds in the hands of his dutiful apprentices. The future, as bleak as it had been foretold, should have seemed bright, but inevitably, distrust stirred between the five, which soon turned to conflict, which eventually turned to war. And that great war, waged over the light of Kingdom Hearts itself, enshrouded all worlds in darkness, just as the Master prophesied would come to pass.

In the end, when the light was reborn and the worlds—restored yet now disconnected—returned with it, the mystery and allure of Kingdom Hearts and the unimaginable power it posed still stood, beckoning hearts filled with enough greed and lust for power to try and claim it as their own. And yet, each of those hearts missed one, or rather thirteen essential pieces of the puzzle, pieces that would indeed bestow the might of Kingdom Hearts and all that entailed to them without question.

For, just as the Master of Masters had told his apprentices centuries ago, whoever claimed the thirteen Keys to the Kingdom would be destined to rule not only Kingdom Hearts, but every single world under its bright, all-encompassing light, now and forevermore.

AN: So yeah, something of a dry prologue (Back Cover is a bit of a snore in my opinion, though the Master of Masters is pretty interesting!) but needed to set up some important plot aspects for the rest of the fic, so I can't complain. Either way, next time around we'll focus on some more immediately relevant stuff, which will be pretty fun. So yeah, if you liked this, don't hesitate to follow/favorite/and most importantly REVIEW! Feedback is what I thrive off of, so I'd love to hear yours! And with that, I leave you (though not for long since I'm going to post the next chapter immediately after putting this one up lol). Until next time! :)