Author's Note: Hey, everyone, nixofcyzerra here! This is my first story in both the FSN and the KH fandoms, so I'd like to quickly bring up some points.

1) There will be spoilers for both the Type-Moon and Kingdom Hearts franchises.

2) I'm completely open to constructive criticism. Please let me know if I make a mistake regarding the mechanics of either universe, so I can correct it.

That said, if you don't like a plot point or something, I'll hear you out as long as it's not an angry rant or something, but obviously I have the final say on such matters.

Right, now that we've got that out of the way, let's do this!

Disclaimer. Fate/Stay Night and other material taking place in the "Nasu-verse" belong to Type-Moon. Kingdom Hearts is developed by Square Enix and owned by Disney. I personally hold no copyrights nor own any franchises.

*Prologue - 14 Years ago*

Powerful, metallic wings beat as the hooded figure travelled onwards through the ocean of space. It was dark, with nothing but sporadic nebulae to break the monotony, and countless distant stars the only supply of light. Despite his advanced age, the man's arm showed no strain from the weight of the comatose boy he carried underarm, wrapped in a large white cloth. The little of the boy that could be seen included open, unfocused eyes that showed no sign of consciousness or awareness.

The boy was dying, entirely due to the hooded figure's actions. This did not trouble him at all, as the very wound that had sealed the child's fate had also born one of the two tools necessary to bring his grand plan to fruition. However, he was willing to grant one final act of kindness, and allow the boy to live out his final days at his own place of birth, the islands that he himself had found so constricting as a youth.

Of the infinite array of the dreams of Akasha that make up the Kaleidoscope, the majority would have the black-clad individual continue to his destination unhindered and without distractions. However, in this particular realisation of possibility, the most improbable of events began to unfold.

The trenchcoated man froze, sensing something amiss, unexpected. A silver goatee peeked out from inside the black hood. He quickly scanned his surroundings for the source of this sensation, using more than just his sight alone, but neither his eyes nor his more esoteric methods of detection found anything of notice.

"A surge... A surge of the purest darkness!" he muttered to himself, his eyes darting around. His voice was raspy, as if he had gone days without speaking.

Continuing to seek the origin of the darkness that had flickered across his perception, the shadowy figure's gaze eventually came across something that could not be described as a source of light, but rather an area he could only think as slightly less dark. The difference between Taupe and Pitch Black.

The trenchcoated individual moved forward, eager to study a new, unfamiliar phenomenon. A few moments of observation allowed him to realise the nature of what he stood before.

"A barrier. A barrier like nothing I've ever seen. Hiding what lies within, and protecting its contents from..." he trailed off. "Had that surge of power not occurred, or were I not right here at this exact moment, I never would have come across it. And it's already beginning to heal, like a scab over an open wound," he murmured to himself, before ending his ruminations as he decided upon a course of action.

Extending his free arm forward, as if reaching for something, the four dark, asymmetrical wings and the back-mounted platform they extended from vanished, only to be immediately replaced as a sword with a demonic motif appeared in the man's grasp. The materialised sword was evil looking; it had a spiky, black guard resembling demonic wings and just above the handle, there lay a horned, demonic face engraved on the hilt. It had two barbed shafts that, unlike a conventional sword, did not taper to a point, with a blue, cat-like eye embedded just above them, and teeth, reminiscent of a battle axe, extruded from the top of the blade and split into three protrusions that were almost claw-like. Both the shaft and the head of the weapon were adorned with twisting, silver patterns.

Despite the disappearance of his method of propulsion, the enigmatic figure and his burden floated, untouched by gravity's pull. With a steady, almost languid movement, the cloaked individual pointed his sword forward, and the top of the blade emitted a thin beam of light. Upon reaching the area that had intrigued him so, it stopped, having struck a physical object, and erupted into a darkly-hued orb with a shining light in the centre, a doorway which the coated man eagerly passed through, still carrying his former charge.

It was still dark on the other side of the doorway, but it was only the darkness of the night. The doorway had led to the roof of a mountain temple, on the edge of a large city. The enigmatic figure, his features still hidden beneath his trenchcoat, lowered the comatose boy to the surface of the temple roof, and surveyed first his surroundings, and then the city before him, absently noting that it was seemingly divided into two sections, one modern, the other traditional. Probing deeper into the land the city laid upon, searching for the source of the phenomenon that had captured his interest by reaching out with his senses, he let out a sudden gasp of shocked realisation after only a moment.

"Could it be?" he exclaimed. "Any living being is made up of the three components. Why would this not apply to worlds? But this world... this world has more than just the spark of life! This world's soul, no, it's will, is so much stronger than most. It has more than just a dull, reactionary, sentience. This world is cognisant! Sapient! It thinks! Enough to construct a barrier that renders it invisible to outsiders!"

"And if it can think," he continued slowly, "Then it can have an agenda. How utterly fascinating." Considering his options, he let out a sigh of almost-amused disappointment. "Still, this is no time for investigation. I cannot seek out that source of that earlier surge either. If I remain here for much longer, then the barrier will restore itself enough that I'd have to heavily damage it to make my exit. And I'd prefer not to draw the attention of this world's will. For now, anyway."

Turning, the man shrouded in the black coat walked towards the opening he had carved, stooping to collect the boy lying against the nearby tree. He still had to deliver the child.

"...Open the door..."

Suddenly, the child showed a sign of life by rolling over, much to the cloaked figure's startlement. His mild surprise turned to utter astonishment when the boy, still showing no sign of recognition or conscious thought, raised his arm and summoned his own weapon, black and gold in colour. Glowing, the blade fired a beam of incandescent light upwards, into the sky.

Quickly recovering from his shock, a smile curled on the old man's lips. He would not need to find a replacement. Still, he had to move swiftly. Such an occurrence may have caught the world's notice. Once more tucking the again-comatose child under an arm, he strode over to his point of entry, and again opened a path allowing him to leave.

Once more in the ocean of stars, he turned to where he knew his latest discovery lay, once again invisible to the naked eye, before raising his blade and channelling power through it once more. "There. A beacon within the barrier, like shrapnel caught in an open wound, will allow me to easily locate this world again, once my plans have come to fruition." And with that, the fearsome wings emerged in a flash, and the strange duo vanished into the darkness.

*Interlude 0-1*

Worlds away, in a wasteland absent of civilisation, a boy trained his swordsmanship. A strange, inhuman construct leapt at him, only to meet it's destruction at the edge of his blade. His victory granted him no reprieve or relief from his inner demons, however, as it's end only caused him more pain and irritation.

This masochistic routine would have been repeated in a ritual of self-loathing, were the boy's training not unexpectedly interrupted by a sharp, sudden pain in his chest. Falling to the ground, the young man struggled to even remain conscious. His awareness of the outside world fading in and out, the boy could feel darkness encroaching upon him. He could almost hear another person's voice.

A distant part of the boy's mind not incapacitated by pain or fear observed that, despite being the only living being around, he could in fact hear a voice, and absently noted that he was now suffering from an auditory hallucination.

Light.

"Let's open the door."

The boy opened his eyes. The pain was gone. And there was something else. Something had changed. The boy staggered over to a nearby puddle, a remnant of the recent rain, and stared at his reflection.

"...Huh. Kinked Eyebrows."

interlude out

End Prologue