Instant Plot: Just Add Kyubey
Disclaimer: Ranma 1/2 is property of Rumiko Takahashi, Viz Media and Shogakukan. Puella Magi Madoka Magica is property of Gen Urobuchi, Shaft and others. Used here without permission and without intent to profit under imaginary licence.
"Why did you have to leave us, mama..?" Eight-year-old Nabiki Tendo wept, staring at her mother's grave. The funeral was over, Daddy had taken Akane away to give her a moment to say goodbye. "How are we gonna live now? Daddy can't look after us, and I'm too little..." she rubbed her eyes, but it was no good. They only filled with tears again. "Why can't you come back..?"
"Nothing can." A voice told her, and she imagined it was coloured with sympathy. It sounded like a young boy, her own age, or maybe a girl a little older. "But I can help you... all you have to do is make a wish."
Nabiki looked up to see a small, white cat-like creature standing on her mother's grave.
"A wish..?" She asked, trying to keep the despair out of her voice. "W-what do you want?"
"You're a smart girl, and skilled. What I'm offering you is a chance for revenge. Your mother was killed by a witches' curse. They go around spreading misery and suffering, but normal people can't see them. In return for a wish, I want your help. I can give you the power to fight witches if you form a contract with me."
"But what wish should I make, if mother can't come back?" Nabiki asked, successfully drying her eyes this time.
"Death is part of entropy, even we can't turn it back completely. But I can give you the next best thing." The creature told her.
"O-ok. I'll do it... I wish... I wish my family would have someone to always take care of us." She told the cat-creature.
"Contract accepted." It replied, before its eyes glowed softly. Nabiki felt her body burning, like it was on fire, as something attempted to rip its way out and upwards through her chest. A green glow surrounded her for a moment, before coalescing into a small, wire-bound egg that floated into her cupped hands. She stared at the newly formed Soul Gem for a moment, before knowledge slid into her mind. In the depths of the Gem, she watched as her father's and sister's memories were altered, paperwork was misfiled, and a beautiful, brunette girl who looked like a nine-year-old version of her mother condensed into being beside her.
The moment was broken as her haemonculous 'sister' hugged her gently from behind.
"It's ok, little sister. I'm here now, and I'm going to make sure everyone gets on just fine." The haemonculous told her. "All you have to do is give me a name, and I will be everything you wished for."
"Ka-Kasumi..." Nabiki whispered. "You're made from fog and mist, so... Kasumi."
"Thank you, little sister." Kasumi murmured. "Shall we go..? Mother wouldn't want us to slip into despair because she's gone."
"No..." Nabiki whispered. "She wouldn't , would she?"
Nabiki, age seventeen, grimaced slightly as one of her golems was swarmed over by familiars and crushed by their little hammers. This was one of the most powerful Witches she'd ever seen, and its legions of mallet-wielding imps were having little trouble with the paper and clay shikigami she'd called up. Maybe it was time for a change of tack.
Touching her Soul Gem, Nabiki called on her power again, wincing when it grew significantly darker. This could get dangerous. She directed the magic with her will, creating a paper dragon easily thirty feet long that swept down on the swarm of Carvers, spewing poison gas from its mouth. The winged critters fell in droves, leaving her remaining clay golems to swarm the witch with their bladed arms, the two-foot servants cutting the monster apart with precise strikes. As the witch fell, the barrier shattered around her to leave her standing in a dark alleyway. The dragon and golems vanished, turning to ordinary paper and blowing away as the magic holding them together was dismissed.
Nabiki stepped forward to sweep up the Grief Seed, before touching it to her Soul Gem for a moment, just to stave off the darkness a little for now. She would use the rest when she got back to the house, since Kyubey wasn't around to dispose of a charged Seed right now.