credit goes to a Bloodborne/Dishonored crossover on AO3 called Moon and Tide for this fic's inspiration.
the Bloodborne ending used is Honoring Wishes, not Childhood's Beginning. for clarification: Honoring Wishes is the one with only one final boss after the wet nurse.
To those few who know of its existence, the distorted, fractured domain of Giratina is the Reverse World. It represents possibility, the good and the bad and the neutral: all that the true world it reflects could be if physical laws held less sway, if the day-to-day living of pokémon and humans impacted the planet to their full extent. When a magcargo's skin heats to a temperature that should boil the air for dozens of meters, it's the Reverse World that shepherds away the brunt of the devastation. When a human captures Celebi and makes an incoherent eddy of time, it's the Reverse World that calms the ripples.
One wouldn't be wrong in believing that. But if the Reverse World was nothing more than a crutch for the true world to break its stumbles on, Giratina could never stand on equal footing with its siblings, the dragons of space and time. As just another dimension that borders the one that hosts the largest concentration of pokémon life, Palkia might as well claim dominion over it and render Giratina redundant.
The first incorrect belief, and the one from which all other errors stem, comes across in its names: those who've discovered it assume that the Reverse World is the plane on the wrong side of the mirror.
The Reverse World is the origin. From it came space and time and matter and spirit, and so the rest of the universe unfolded in fractals around it. And when the last star fades from the sky, heat and light and gas misting to black, it will be to the Reverse World that the universe returns.
Until that moment comes, Giratina prolongs the inevitable.
Aerodactyl live and die, Regigigas pulls continents apart as easily as a graveler makes a nest from boulders, humans realize increasingly creative ways to keep their settlements intact on a planet where common rodents can call down lightning from the heavens. Giratina steadies a fault line shaken by two onix's passage, repairs the soil trampled and salted in an army's wake, corrects the gravity disrupted in the aftermath of an argument between powerful psychics. With some exceptions, life is a transient thing; the dragon keeps track of its passage only through its patterns.
Some exceptions referring, in this case, to the small creature falling through the air. It's not unusual. Dimensions have their own sort of gravity, and when they move – as they do – they overlap at points. Things come through.
It's a process easily reversed. There are always portals opening and closing between the Distortion World and its reflections. Giratina used to leave the creatures who come through by accident to their own devices, but that was before it discovered that a fall – not the impact, because that's always harmless, but the fall itself – can kill.
It only happens rarely, but there's no clear connection Giratina's found between those who die that way that will let it predict when it will happen. The dragon's simply taken to treating it as a possibility every time.
The unfortunate soul is a fair ways off, a speck of motion against nebulous darkness, but distance is malleable. Giratina curves beneath a brook coursing unsupported between two drifting islands, through the rose window of a cavernous building that in the bordering world is a chapel dedicated to the three lake sprites, and when it comes out the other side of the roof the creature is falling directly above it.
It's an enterprising thing. As it passes an island, a bulky, segmented blade that extends with the creature's swing scores a gash into the rock. The blade slips free quickly, but before the creature's plummet picks up speed again Giratina snatches it out of the air.
It panics as soon as the dragon's mandibles close around it. Understandable, but irritating; when, in its flailing, the blade scrapes painfully across the crown protecting Giratina's eyes, the dragon drops it without remorse. Giratina swings around, phases through the blade and the scattering of hypersonic projectiles the little creature sends its way, and catches it again from behind, this time maneuvering to pin its arms in.
Giratina retraces its visitor's path, searching for the traces of the portal it came through. Usually the dragon would simply leave it on the nearest solid surface, but this one fell far enough that it likely won't be able to get back to its entry point on its own. Returning to their own worlds near where they left seems to make the experience less disorientating for them.
As they climb, the creature tries to wriggle out of Giratina's hold. The dragon tightens its grip, carefully so as not to fracture any fragile bones, and the creature finally goes limp. Giratina glances at it, not worried, but... well, a little concerned. It doesn't know why things sometimes die in the air, after all. The view's difficult enough at this angle and distance that it can't make out details; the blade and the projectile launcher haven't slipped from the creature's hands, though, so the lack of movement seems to be voluntary.
As they pass through a cloudy fold of space, gravity spins neatly on its axis. The creature startles, and the dragon, reassured, turns its attention away. Its passage disperses the thin haze to reveal clear, fathomless water stretching for miles across below. In other worlds, this is where sea meets sky. The creature can't be from past this place, yet Giratina came across no portals on the way. The dragon slows to a stop near the surface and looks over the scene reflected below, the floating islands and the clouds and the crystal shards that are windows to other planes, searching for what it may have missed.
An arm squeezes free of Giratina's hold. The creature reaches out. Faint ripples spread where the tips of its fingers brush the sea. They pass over the reflection of Giratina, over an eye. The red iris bright as coals waxes large and luminous under the waves, and the thing looking back from the water isn't Giratina at all.
The dragon recoils, jerking the hand away; the instant snaps. The reflection shatters against its scream, a call that's query and threat and declaration of self.
There's no reply. As soon as the sound fades, the sea rushes in to fill the hollow. Giratina looks down at itself, at the creature with its free hand curled into a claw against the dragon's mandible. Giratina's spooked it. Its ribs are expanding and contracting visibly with its breaths.
The dragon flips around, leaving the water behind. It weaves through the branches of a great stone tree; coming out the other side, the sea is gone, and the rising sun tints every cloud a lighter purple and casts a faint glitter over a maze of frosted isles. Giratina lets go over the base of a cliff, and its visitor lands on its feet in a patch of snow that nearly reaches its knees, stumbles a step for balance, and then trips with a crunch of breaking ice.
Giratina hovers while it unsteadily picks itself up. In retrospect, this might not be an ideal climate to have placed it in. It doesn't have any flames or ice or thick fur on its body, some of the common physical traits of fire types and ice types. Still, it likely wouldn't appreciate being relocated again.
It looks up at Giratina. Or turns the dragon's way, in any case – it doesn't have eyes that Giratina can see, just ragged strips of cloth tied around the upper half of its face beneath the head covering. Odd little thing. Where did it come from?
Unfortunately, no matter what form of creature it is, Giratina wouldn't understand it even if it gave a speech elaborating on its origins. There are so many human languages, and they all change so quickly, that it's long since stopped putting in the effort to learn any, and there's a psychic component to pokémon speech that Giratina predates the evolution of.
The creature turns away and takes a few steps to put it out from under Giratina's shadow. There's an odd lurch to its gait unlike in any other bipedal stride Giratina's seen. It doesn't take much deduction to discover why: the footprints it leaves in the snow don't match each other. The left is a sort of oval squished inwards at the middle while the right doesn't seem to have a foot at all, only a thin leg that tapers towards the bottom.
Slowly, it carves a short, straight furrow through the snow with its projectile launcher. Once done, it cocks its head at Giratina for a moment; then, methodically, it clears another line at a slant through the first. Giratina leans over as it makes a third, a fourth.
A fifth line, but even as it begins, before it meets the others, Giratina loses interest. Whatever quality about them roused its curiosity is gone. The creature pauses, then kicks the snow back into shape over it. It starts over from another angle, bringing the line in to meet the others at a different point. Giratina's attention is caught again. A sixth...
In a shift of thought, the dragon understands what it's looking at.
Query and threat and declaration of self. The echo of its own call written in lines in the snow: creation.