he was the sun. he was her sun. they were on opposite sides of the earth, but every time he smiled, she would catch his light. she was the moon; she was dark and she couldn't illuminate without him.
they parted for days, her only seeing him for a few minutes each time they reunited and she yearned for more. she chased him, and he ran from her. she had lots of surface area, but she lacked the light she was so jealous of. he had it. she had an idea: chase the sun to steal his light, then she could shine all on her own. So she did.
after days of chasing him, she grew nearer, slowly. she waxed, and she was so close to him, and he saw her and smiled and she reflected his light so bright even the smallest creatures on earth could see her. but then she got tired; but he was the sun, he was never exhausted. He kept running. And she waned. She got smaller and smaller and smaller and eventually she was so small none of his light could touch her surface. but she missed the light. she missed being whole, she missed watching the eyes of the humans shine with the light she had stolen. she wanted to be ogled at, to be admired. but now she was small. now she was nothing.
she laid idly for days, dreaming, remembering the hours when she was bright and beautiful, not realizing that she was growing. and she was running towards him again. and she caught up, and once again she reflected his light miraculously off the shimmering waters of earth. she was adored. and again, she grew tired and shrunk. and this cycle repeated itself, decade after decade, for a millennia. she never realized.
she kept running after him, and one day, she ran so far ahead of him that she couldn't catch his light. and she spent the rest of eternity in darkness, watching as he lit up skies and gave life to the earth.
but she didn't notice. while she was chasing the sun, the earth had fallen in love with her; he loved her craters, he loved how mysterious she was. He loved how beautiful she looked as a big moon, even when she couldn't reflect the light the sun had shone at her. he had loved her so much that slowly, over time, some of his species had grown to need her to live. and as she ran farther and farther away, those species couldn't survive, and slowly, the earth died with them.