Obvious spoilers. And you need some knowledge of the anime. When rewatching the end, I thought of this. Too sad.
Color Me Blind.
Aura had slept for a long time.
She had waited, like a small caterpillar in a cocoon, ever so patiently, for when she would be ready to wake up. She thought only in dreams during that long wait, iridescent dreams that shimmered the world of her unfinished mind. She waited, patiently, lovingly, to wake.
Dark turned to light, and back again. She felt changes occurring on her surface, but she was removed from the process. Something shattered outside of her at one point, her being shuddered but she moved past it. It would heal. She had faith in that outside other, the one who talked to the shell of herself like she could understand. She trusted her other, though she never saw it.
Time passed, things changed; light turned to dark and back again. And then she started to wake.
Colors. Her eyes saw colors, created colors around her, were colors themselves. When she got over the sheer fact of seeing and existing, that's when she noticed him. The other. The one who she trusted with a thought, and was unavoidably linked to. Tsukasa.
Morganna, her pseudo-mother, pursued them when she woke. Still in an in-between state, Aura ran with Tsukasa, and the two girls that loved him. They ran, and she kept seeing, kept experiencing, all the colors and things around her. This was her world, this was her, and she was starting to see it for the first time.
She was still waking, clarity interrupting her blurred vision. She heard the rumble of voices; others joining her only family, Tsukasa, in a fringed group. The sky shuddered above them, and a lost part of her and Morganna appeared corrupted and desolate before them. The murmur of voices increased, and a new one sounded, like a ringing bell. Then the world disappeared before her newly-opened eyes.
She was Aura, she was The World, and so she simply went to a different place. But the others, and her other, were nowhere in it. That was fine with her; she would wait for Tsukasa to return to her.
Waiting she was used to. She had waited to wake, without even considering impatience or anything but perfect grace. She would wake, because she was supposed to. It was absolute. Tsukasa returning was not. It wouldn't cross her mind for months, not until she had been found by Skeith again, after she had ran again, this time alone and lost within herself, stumbling across her reality, learning about what tears were. For months she waited, before realizing Tsukasa wasn't going to come back.
She owed her life to her other. She woke because of Tsukasa. Tsukasa was everything to her, her older sibling who held her hand as she ran. A part of her, a piece of her created soul. Tsukasa was her light, as she was the light of The World.
And when Tsukasa left, he didn't look back to see what he had left behind.