Hey, remember that one reply I posted in a /r/RWBY thread ages ago? Well guess what, I'm gonna go ahead and tweak the circumstances a wee bit.

Last month, Yang Xiao Long turned seventeen and a half years old. Last week, she lost her right arm in defense of her school against a terrorist attack.

Yang groaned as she stretched out her arm to silence the air raid siren she had set as her scroll's default alarm clock. Suddenly realising she couldn't feel anything below her elbow, she looked down forlornly at the stump that remained of her right arm before rolling her torso over it with some difficulty to reach her scroll with her remaining left hand. Swinging down her legs towards the floor as she rose to a sitting position, yang picked up her scroll and shut off the noise.

Might as well try to get something done today… Can't wallow in self-pity forever.

Taking a deep breath, Yang swung her body forwards and upwards to a standing position. Walking over to her closet, she once again found herself reminded of her loss as she reached to open both doors, instead having to open them individually. She pointedly avoided laying eyes on her combat outfit that Taiyang had hung up after she got home, and made a large curving motion around her boots with her gaze as she picked out her daily wear from the drawers at the bottom. Settling on a gray jeans jacket over a sunset-coloured tank top and cargo pants, Yang started walking towards the door of her room to get something to eat from the kitchen. Idly picking up her scroll as she passed it, she began to dial a by now very familiar number.

"C'mon, please pick up this time, please please please… Blake?" A tone.

"We're sorry; you have reached a number that has been disconnected or is no longer in service. If you feel you have reached this recording in error, please check the number and try your call again." Yang threw her scroll on her bed in disappointment before walking out the door and into the main living area of her family home on Patch Island.

"Yang?! You're out of bed?!" Taiyang practically shot out of his chair by the breakfast table as he rushed over to his eldest daughter. Yang couldn't help but chuckle a bit at her overprotective father.

"What dad, stumped already?" She said while wiggling what was left of her right arm.

"What."

"Haha, you should see your face right now! Pure comedy gold! Pass me the Fruit Loops, please?" Taiyang just stared as he pushed the cereal box across the table. Yang fidgeted a bit to get the lid flaps open before finally pouring the cereal into her bowl with milk.

"Glad to see you up and about again, Yang."

"How can you know this isn't just me burying all my angst and sorrow behind a mask of happiness, hmm?"

"Yang."

"I'm fine now, dad. Honestly." Taiyang's eyes never left his daughter as he stretched his arm over to the pile of letters, magazines and flyers he had brought in from the mailbox out front earlier.

Rummaging through the hoard, he pulled out a small envelope and handed it to Yang.

"This was addressed to you, by the way. Plain white envelope, no return address, and your name on it, handwritten in the fanciest style I've ever seen."

Could it be…?

Yang accepted the letter from her father's outstretched hand, and gently (albeit with some difficulty) pried the envelope flap open. Inside was a folded letter, emblazoned with a crystal-white snowflake logo with a bright-blue W adorning it.

Dear Miss Yang Xiao Long,

You have been selected as one of a few candidates for an experimental new prosthetic technology, and we would be honoured if you could attend this coming month. All expenses for your travel, lodging and medical bills will be paid for by the Schnee Dust Company.

Sincerely,

Weiss Schnee

SDC Heiress

SDC Headquarters

Atlas

P.S I could probably sneak in Ruby as a +1 on your account. I really miss you guys. Please think about this. D.S

Yang read the letter two more times before silently handing it over to her father.

"As your father, I say you've thought about it enough. You're going, no buts."

"Gee dad, way to be an ass. I've already decided I'm going." Taiyang frowned.

"I'm glad you're well enough to joke around, but you're giving your old man whiplash from this 180 in mood…"

"Heh, sorry. I'll try to mope more around you."

"Want help with packing?"

"Thanks dad, but I'll manage. Besides, you're not getting rid of me for another month."

The next few weeks Yang spent working out in her father's improvised gym (formerly their cottage's sitting room) doing an equally improvised training regime, devised to get rid of Yang's "bed-body" in time for the surgery. Three days before the "big day" (as Taiyang would never cease referring to it), they both travelled in to Vale's central airship terminal to charter a flight to Atlas. Right outside the terminal they met up with Ruby at their pre-determined spot, before walking inside to get their tickets.

"So, Ruby… what've you been up to while your big sis was all mopey and un-fun?" Yang casually asked her sister as they waited to board their flight.

"Well… I've tried getting any word from Weiss (good job on upstaging me there by the way)…" Ruby playfully pouted at Yang before continuing.

"And I've also been spending some time with JNPR, seeing as how they nearly lost Pyrrha during the battle for Beacon. They're not my teammates, but RWBY and JNPR will always be friends." Ruby's cheerful expression changed into a look of concern.

"Speaking of teammates … Still no word from Blake?" Yang kicked at the ground, avoiding Ruby's gaze.

"… No." Ruby leaned in and hugged Yang with her left arm.

"I'm sure she's fine, Yang. Blake's probably got more life experience than you, me and Weiss combined."

Yang was about to reply when a voice came in over the PA system, announcing boarding time, and the three members of the Xiao Long-Rose family joined the mass of people boarding for Atlas.

The next two days were spent in agonising anticipation in a pre-booked hotel room, neighbouring with the rest of the invited test subjects. A young girl, born with no legs below her knees. An old man who had lost a hand in a wood chopping accident. A woman who had lost her leg to an infection. Yang felt with them all, but she also knew that since this was an experimental treatment, it might not work for all of them. She prayed that at least the spirited little girl in her wheelchair would be a success. She and Ruby was currently engaged in a high-stakes race to see who could eat a tray of rusks the quickest. Yang suspected that Ruby was throwing the match to empower the girl's feelings – Ruby had almost half her tray left, while her diminutive opponent was nearly done.

"Aww, you beat me…" Ruby said with an exaggerated pout.

"It's okay Miss Rose, you fought well. I was simply better this time."

"Thank you kindly for your kind words, kind maiden. Would you mind if I took the rest of my rusks to share with my sister?"

"Not at all Miss Rose." Ruby thanked the girl once again and returned to Yang's table with the tray of rusks. By the time Yang had raised her hand, picked out a rusk and transferred it to her mouth, Ruby had already demolished over half their share.

"Hey sis? Leave some for me too?"

With only an hour left until the surgery, Yang and the other seven test subjects had switched to their provided hospital gowns and laid down in their hospital beds. As Yang was wheeled into her operating room for sedation, she was met by a gaunt, tall man in a lab coat standing next to a desk. On the desk was a glass case with Yang's new arm on display.

"Hello, my name is Doctor Schwartzmann. I'm the one who's going to get you your new arm. I just brought her here so you two could get… reacquainted." Yang blinked.

"Huh?"

"I'm told you were pretty close. Why don't you say hi?" Dr. Schwartzmann addressed the arm as he opened the case.

"Sal-U-tations, friend Yang!" Yang's eyes nearly popped out of their sockets.

"Penny? But… We saw you get ripped to pieces!" The arm projected a small blue hologram of the former gynoid, clutching her stomach as if laughing heartily.

"Don't be silly, friend Yang – you can't kill an artificial lifeform that easily!"

"I guess that's true. So why are you in my new arm, exactly?" Penny had no time to answer Yang's question as the door to the room swung open, and Weiss Schnee strode in.

"I can answer that, actually." She walked up next to Yang's bed and put a hand on her shoulder.

"I'm terribly sorry for how I left you after the battle of Beacon by the way. My father and his men came and took me back here to Atlas out of concern for my well-being." Weiss made air quotes around that last part. "As to why Penny is in your new arm… the human nerve system is complex in and of itself, add the factor of Aura into that, and well… Basically, your prosthetic arm needs at bare minimum a rudimentary A.I and Penny… well, to put it bluntly she volunteered." The holographic penny popped up in-between the two friends.

"Indeed so! I saw it as an opportunity to eliminate two avians with one mineral! I get to be close to you and friend Ruby again, and simultaneously fulfil my original purpose to help people… In a way, at least."

"But couldn't you do that more easily with your original body?"

"Hmmm… I had not thought of it like that. You raise a fair point, friend Yang. Although you have to understand that life as a synthetic lifeform here in Atlas-" Penny's hologram cast a quick glance towards Weiss, as if to gauge her loyalties.

"… here in Atlas is not as free as a simple organic lifeform's. I am simply military property here. I have to follow strict orders as long as I am my own 'person'. But if I instead act as your arm, you can protect both our personal interests, as I effectively become your property."

"I can see why the Atlas military would have no business telling me what to do with my own limbs, yeah." The small hologram looked away while fidgeting with the hem of her skirt.

"I would also have one small request if you accept having me – don't tell friend Ruby straight away. I want to make it a surprise."

"Okay, deal." Yang smiled.

"It was nice meeting you again, Penny. I'm sure Ruby will say the same."

As Yang was once again wheeled out of the room for the doctors to make final preparations, she wept silent tears of emotion.

"Ready to begin, Miss Xiao Long?" Dr Schwartzmann leaned over Yang on the operating table.

"As ready as I'll ever be. Hit me." The doctor held up a breathing mask to Yang's face and spoke softly.

"Now take some deep breaths and think of things that make you happy…"

"… Cats. I love cats." Yang interjected as she halted his hand holding the mask.

"Very well. Deep breaths, and think of cats."

He put the mask snugly over Yang's mouth, and she obediently drew a deep breath. Two amber orbs.

Another breath. A mass of midnight-black, billowing hair.

A third breath. Two of the most adorable cat ears Yang had ever seen.

Darkness.

Yang awoke with a start.

Had it all just been a dream? She looked down at her hands. Her hands. They were both there.

"Sal-U-tations friend Yang!" She jumped high from the sudden voice.

"... Penny?" She looked down at her right arm, where the small, blue-tinted hologram of the gynoid floated. The hologram tilted its head as it looked up at Yang. "Would you like to hear today's schedule first, or should I run a diagnostic for the arm?"

Yang could feel the happy tears start welling at the edge of her eyes. She laughed softly.

"Run the diagnostic, don't bother telling me if there's nothing wrong, and I'd love to hear the schedule."

Scathing eyes ask that we be symmetrical, one sided and easily controlled. Yet every misshapen spark's unseen beauty is greater than the sum of its parts.

AN: And there you have it, one expansion of the Reddit comment that started my entire AU.

I do not own RWBY, that's RoosterTeeth and Monty Oum.