A Fragmentary Passage
Terms and lore
The realm of darkness. Where Aqua has been walking since she went down after Terra. By her own account there is no time there: "I walk on and on without end." When she asked Mickey how long it had been in the realm of light, the answer was about ten years.
Dwellers of darkness. Aqua's name for the creatures of the realm of darkness. Mickey had another name for them: "They're called Heartless!"
Lost worlds in the dark. Worlds the darkness has consumed turn up in the realm of darkness, broken and empty. Aqua walked through Cinderella's world, past the cottage in the wood where the dwarfs lived, and up the thorn-choked mountain of Enchanted Dominion. The houses are still standing and the people are gone. Aqua took what comfort she could from that: wherever they went, they had not fallen to darkness.
The clock. In Cinderella's world the road collapsed whenever the castle clock moved forward. "There is no time in this place, only the clock." Aqua turned a gear of it backward, and the road came back.
Phantoms and memories. "The world keeps our thoughts alive," Aqua decided, after a figure of Terra stood silent on the road and vanished. Ven appeared asleep in a glass coffin, and then the coffin was gone. Terra's own explanation, when he could speak: her heart was painting the picture it wanted to see.
Aqua's phantom. Aqua's own reflection, pulled out of a mirror: her height, her clothes, her Keyblade, with lighter blue eyes. It told her things she refused to believe and tried to destroy her. She fought it three times. Her conclusion: "She's the weakness in my heart," all her doubts given a voice of their own.
The Chamber of Waking. Where Aqua hid Ven: the throne room of the Land of Departure, sealed inside the labyrinth she made of it. She told Terra he was hidden well. When the voice speaking through Terra asked whether the place was the Chamber of Waking, she said yes before she understood who was asking.
Crossing into the dark. Mickey's account: the points where a person can cross into the realm of darkness have become unstable, and an entrance only opens in the realm between when a world is consumed. He waited for his chance and slipped in.
The Keyblade of darkness. The counterpart of the Keyblade in the realm of light. Mickey reasoned that it would lie on the dark side of the world where Sora and Riku first got the Keyblade, and found it standing upright in the cave on that island. The old lines he spoke over it: "The door of darkness, tied by two keys. The door of darkness, to seal the light."
The door to Kingdom Hearts. "It's not the Kingdom Hearts you know. Not exactly," Mickey said, but it is still the heart of many worlds, and left open it would let darkness out to destroy the remaining worlds. It will not let a heart with light pass through. It had to be locked with two Keyblades, one on each side, with help on both sides to push it shut.
"May our hearts be our guiding key." The words Keyblade wielders used to say to each other, which Mickey still tries to remember. Aqua said it was a phrase nobody had used in ages. She said it again at the very end, to him, so he would know where she was.
A wayfinder. What Aqua vowed to be for anyone else who wanders into the realm of darkness: "A light to cut through all the shadows." Mickey found her by following a warm, familiar light, and she understood it as the charms at work, Terra's and Ven's bringing the two of them together.
Characters and where they stand
Aqua. Steadfast and duty-bound, and after ten years of walking alone, afraid that the darkness has found the cracks in her heart. She talks to herself because there is nobody else. She fought her own phantom and won, and she found Terra, for a moment, before Xehanort took him back. With Mickey she found the Keyblade of darkness. At the shore she held back the mass of Heartless coming for the boy on the sand, and it came down between her and Mickey. She lost the Master's Defender, and the sand gave way under her. She calls herself Master Aqua, and she has promised to return to Terra and Ven.
Terra. Or what Aqua could reach of him. "I promise this is me. But I'm not myself." His heart has ties to the dark, which is how he could speak to her, but he cannot see, and he could not see Ven. Xehanort is part of him and was using him to learn where Ven is hidden. Terra broke through long enough to warn her, and then to throw chains of light between her and the hands dragging her down. "The real me is lost in shadow."
Ventus. Asleep in the Chamber of Waking, where Aqua left him. He appeared to her in the dark as a sleeper in a glass coffin and as a silent figure on a mountain path, and said nothing.
Master Xehanort. Part of Terra now, and speaking through him. He wants to find Ventus, and he asked Aqua the right question at the right moment.
Mickey. Cheerful, practical, and unembarrassed about having found a way into the realm of darkness with no plan for getting out. He came to find the Keyblade of darkness so the door to Kingdom Hearts could be locked from both sides, and found Aqua on the way. He is closing that door with Riku from the dark side and with Sora from the realm of light, and he lost sight of Aqua at the shore.
Sora and Riku. The two boys Aqua once met on the islands, and considered passing the Keyblade to. They are the ones helping Mickey close the door. A silver-haired boy, taller than she remembered, came onto the dark shore, and she put herself between him and the Heartless.
The figure in the wasteland. Long before any of this, someone stood alone in the wasteland of old Keyblades with a Keyblade in his hand, and watched Kingdom Hearts rise in the sky.
Questions
Who stood watching Kingdom Hearts rise over the wasteland of old Keyblades?
What will Xehanort do now that he knows Ven is in the Chamber of Waking?
Can Terra ever be free of Xehanort?
Where did the Master's Defender go?
Where did Aqua fall to when the sand gave way beneath her?
Will Mickey find Aqua again?
Will Aqua ever find her way back to the realm of light, and to Terra and Ven?
Fun facts
A game inside a collection. The game this entry adapts came out in January 2017 as part of Kingdom Hearts HD 2.8 Final Chapter Prologue, as an epilogue to Birth by Sleep.
A new engine. It was made in Unreal Engine 4, and its controls were designed to prepare players for the next main game rather than to copy Birth by Sleep's.
A Master from the start. Aqua begins the game at level 50, and the whole story takes only about two or three hours to play.
The twelve signs again. After the story is finished, twelve zodiac symbols can be found hidden in treasure chests. Collecting them all opens a new mirror leading to a five-round battle, the last against a stronger Phantom Aqua.