~Author's Note~
Technically, Wonderweiss first appeared in episode 138 and my story begins just after episode 159, so I'm taking some artistic license here. Won't make a big difference, though.
"Fifty percent."
"Fifty percent what?"
"The Hogyoku is fifty percent awakened, as planned, Yammy."
"And what do you plan to do with it now?" Ulquiorra asked Aizen.
"Create a new being. A purer being. Granted, there will be a tradeoff. Though physically refined for combat, its intellect will be rudimentary at best. Of course, that means it will do exactly as I say."
Orihime shifted uncomfortably as she leaned against the wall, watching Aizen reach out to touch the Hogyoku in its crystalline case. He did so gingerly, as if afraid it might break. He did not, in fact, actually touch it; it touched him. Its metallic sheen darkened until it was totally black, and delicate tentacles extended from its surface to palpate his outstretched hand. Just after the tentacles of the Hogyoku made contact with his hand, there was a flash of light. Before the brightness of the light became blinding, Orihime could make out a quivering, misshapen form, completely covered in bandages inside a large crystalline box, enveloped by the light.
The light dissipated and a small and slender form shifted in the darkness.
"Comrade, what is your name?"
"Wonderweiss…Wonderweiss Margera," said the creature in airy, lilting tones. Orihime could see it now. It was not an it, but a wiry little boy with an unkempt thatch of blond hair. She looked on in shock.
"The Hogyoku's power is amazing, is it not, Orihime?" Aizen said offhandedly, "It's why you're here, you know." He turned towards her with a cold smile. "Every time I use it, it deteriorates just a little bit. But you, girl, with your extraordinary power, can reverse that process."
She wasn't listening to him, she was looking at the boy. He was very naked and completely nonplussed, looking up at her with a sheepish, moony face.
"H-how could you…he's just a child…"
"My dear, he only looks like a child. I assure you, he can fend for himself. He's doubtless more powerful than some of the Espada." Yammy shot a poisonous look at Aizen's back, but Aizen waved him off. "Certainly not the two of you, but powerful nonetheless."
Wonderweiss gave her a lopsided grin and a wall-eyed stare. She reached out to him, tears flowing freely down her face now. He took her hand and crouched happily at her side.
"Now, for the formalities. Ulquiorra, take her please."
"Come, onna." She left, wondering if she'd ever see the little boy again.
She had wanted to train that night. She had wanted to work on her resolve, on her killing intent, so she could escape and stop her friends before they stormed this hellish fortress to rescue her, the perpetual victim. But she could not get Wonderweiss out of her head.
Aizen had created a weapon from a little boy. And every time she tinkered with the Hogyoku she was granting him a false lease on fate's decree – that a weapon of such power should gradually cease to exist with every affront to human and spirit beings it perpetrated. She resolved to destroy it. If she could not overcome her status as victim, she would at least be a useful victim, willing to put to work the skills she had to undo a great evil. She didn't mean that in self-aggrandizing terms either – she was just a tool, not a hero. Her lack of will, especially compared to that of her friends, made that obvious.
There was a knock at her door. She was free to wander about as she wished – how would she get away? – but she kept it locked for her own safety. As if that would really matter if anyone actually wanted to come in. Initially, she had worried, but no one, not even Nnoitra, had bothered her for whatever reason.
"Who is it?" An incoherent gargle, but one that she recognized, was the reply. She opened the door.
Wonderweiss, now thankfully dressed, entered. He sat on her couch, smiling vacantly, and she started to cry again.
"Hello, Wonderweiss. What brings you here?" She sat next to him and smiled through her tears. He warbled happily and dabbed at her tears with his overlong sleeves. "I'm Orihime." He continued burbling, but she clasped his hands in her own and he stopped and looked at her attentively, or with whatever passed for attentiveness for him. "Orihime," she said firmly.
"Hime," he said absently.
"Orihime."
"Hime."
She laughed. "I'm not used to such a regal title, but I'll settle." She wished there was something she could do with him. There was nothing for it. They would go for a walk. She would brave the long, silent corridors of Las Noches for him. It was the least she could do.
She quietly unlocked the door, and with a sharp intake of breath silenced a scream when she realized Ulquiorra was right outside her door.
"What are you doing here?"
"Making sure you aren't bothered."
"Oh, yes, thank you." She looked at him, somewhat bewildered. He'd never done this before, or perhaps he had and she simply hadn't known. "Would you mind if I went for a walk with Wonderweiss?"
"No. But I must go with you."
"Alright." She started down the corridor. He grabbed her arm, and she felt a chill pass through her. Around him, she felt as if someone were perpetually walking over her grave.
"We are going the usual route."
"Why?"
"I know it best." So they headed the way they always went around midday, towards the uppermost parapet.
Along the way, she tried to teach Wonderweiss the names of things. He managed to seem interested, and by the time they reached the parapet, he was genuinely animated, gesticulating enthusiastically at the things she'd named for him and describing them with his pidgin Japanese. Ulquiorra trailed behind, silent and watchful.
"Wonderweiss, this is my favorite place," she said when they reached the parapet. "Those are dunes."
"Dunes." He ogled them blissfully.
"Yes, that's right." She looked as far she could see and found that she had completely forgotten how miserable she was. Wonderweiss grinned up at her, and she realized she could forget for a bit longer. She pointed up at the perpetual sickle of the moon.
"Moon."
"Moon!" It was tinted lavender in his strange, rheumy eyes. They stood there, gazing into the middle distance for some time.
"We should go," Ulquiorra said without preamble, giving Orihime a start.
"Alright." She took Wonderweiss' hand and he lollopped along beside her.
"Don't walk like that!" she snapped. He looked up at her from where he crouched at her side, confused and hurt. She softened. "Stand up. You are a human being." She pointed at his chest, and was struck by the proximity of that which made him very inhuman – the gaping hole in his torso. Her eyes swimming with tears, she urged, "Stand up."
When they reached her room, Wonderweiss curled up at the foot of her couch and hummed contentedly as he closed his eyes.
"I guess he'll be staying with me, then?" she looked hopefully at Ulquiorra, and he nodded. She sat on her couch. "I'll be going to bed." She looked at the door, expecting Ulquiorra to leave. But he did not. He stood in the doorway, staring at her.
"He's not human."
"What?"
"Wonderweiss. He's an Arrancar."
"Yes, well…" she trailed off and fought to suppress her sorrow. She would not cry about this, not in front of him.
"I don't understand why you pretend that you can find happiness here. You will never be happy here." She looked at him, askance. If anyone else had said this to her, she might have thought it was an expression of pity. But he said it without inflection, without affect.
"Don't take this from me too. You've all taken everything else." She said it without vindictiveness. She was too tired, and did not have the vigor requisite for self-righteousness.
He said nothing and left, locking the door behind him.
~For the Curious Reader~
A Note on Orihime's Powers: I think Orihime's ability to regenerate the dead should be limited, for plot purposes. If she can just bring anyone back, anytime she wants, there would be no reason for her to ever worry about her friends. Heck, if they died trying to rescue her in Las Noches, she could just regenerate them inside her cell and they could fight their way out. I think this is a huge oversight on Kubo-sensei's part – it makes no sense for Orihime and the other characters to not take advantage of this, so she shouldn't have such ridiculously epic abilities. That said, I have complete respect for Kubo Tite, I just have issues with his characterization of Orihime and such problematic plot points concerning her.
So, via my artistic license, Orihime's regeneration of the dead will be limited to regeneration within 5 minutes of death. Also, she can regenerate humans and Shinigami, but not "in-between" beings like Hollows and Arrancar. Furthermore, there is no time limit on her regeneration of spiritual beings like Tsubaki, which explains how she was able to bring him back as Hachi suggested.
Title Explanation: "Velut Luna" means "variable as the moon" in Latin. I became attached to this phrase when I read the lyrics of the choral portion of Carmina Burana, a cantata by Karl Orff. ( youtube .com/watch?v=64SpAIuZ3o0) The "Luna," in case you didn't guess, is a reference to Ulquiorra, who Kubo Tite often associates with the moon. In fact, the theme song Kubo-sensei chose for Ulquiorra is entitled "The Moonshield." ( youtube .com/watch?NR=1&v=xN3O7ZUg1J0&feature=fvwp)