CHAPTER ONE:
THE EXPERIMENT

LONDON, ENGLAND
EARTH
1941

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"BUT I'M NOT A SOLDIER,"
Penny argued with her brother, arms crossed over her chest and a frown on her lips. "I'm not going to fight battles with you, Steve."

"That's the hope," Colonel Phillips glanced in her direction, seated smartly at the round table covered in blueprints. "But on the chance it doesn't work, Erskine wants you as a back-up. Lord knows why, you're a woman and not a very strong one at that. I think there are far better alternatives, but seeing as you're the only one alive with the same DNA as Rogers, you'll have to do."

"Thanks for the vote of confidence," Penny snarked, narrowing her eyes at the older man.

Steve cleared his throat, looking between the two. Small in stature with baby blue eyes and tousled blonde hair; he was quiet and peaceful and brave, and held more compassion in his finger than Penny had in her entire body. 

He was the complete opposite of his bossy, scatterbrained, incredibly clumsy twin sister.

So the idea of taking a life-altering serum with her brother on the off-chance something happened to him and they needed a replacement with a heart like his was...slightly off-putting.

"Pen, it's just in case," Steve pleaded, looking over her face. "Plus, it'll keep you safe. I can't anymore, not if I'll be doing all of this, and neither can Bucky."

Penny looked to Dr. Erskine, the man behind it all. The one who would put the serum into her and her brother in four hours time. His gaze was hopeful; soft, comforting. Trusting.

She glanced back to her brother, who smiled with a similar hope in his eyes.

Penny sighed. "If I die, I'm haunting you all for the rest of time."

"I can deal with that," Colonel Phillips said firmly, nodding to them all before leaving the room.

Erskine walked to Penny's side. He placed a hand gently on her shoulder.

"It's for your own good. And his. And the world."

Penny smiled stiffly and he nodded to Steve before exiting the room, leaving the siblings alone in silence.

"Have you talked to Bucky?" Penny asked after a moment of silence, watching the floor intently.

They hadn't really spoken of their best friend since he'd been drafted. They missed him for different reasons.

Penny already had a brother in Steve. He was her blood. They shared the same eyes, same smile, same chin. He was the other half to her otherwise empty existence.

And so Bucky wasn't like a brother to Penny. When she was younger, Penny harbored a small crush on the handsome brunette, but it fell away when Steve confessed the same feelings one early December morning.

She would never do that to him. So she pushed the feelings aside and in doing so, it made their relationship stronger in another way.

James Buchanan Barnes became her best friend in the universe. If she could pull the stars from sky and scatter them in his eyes so he could see the way he lit up her life, she would. He was beautiful and brave and perfect and there wasn't a single person she loved more than him.

He was her rock, her lighthouse, her boat during the tropical storms of her tumultuous life. He steadied her mind and quieted her dreams. Most nights he slept next to Steve, but almost every morning he'd wake up next to Penny. Just because he knew she needed him.

As a kid she was scared of thunderstorms. The loud claps of thunder startled her already sheepish demeanor and the lightning flickered out lights that kept her room void of darkness.

He coddled her often during storms. Held her close and promised to keep her safe. This continued into adulthood as a new fear arose.

Waking up alone scared her.

Being alone scared her.

She felt alone after her parents' death. As Steve relied more on Bucky to help ease the pain, Penny found herself crying in her sleep and the only one who seemed to hear her quiet sobs was Bucky.

He'd kiss Steve's head and crawl out of bed and into the next room and hold her gently. He'd promise to be there. To keep her safe and secure and never let her be alone.

The three of them were thick as thieves. And at first, Bucky had written to her loads. The trees he'd seen, the people he'd met, the other soldiers, the cot he slept on — but for a week it had been radio silence.

She didn't know why.

"His last letter was a few days ago," Steve said after a thoughtful pause. "He said he's sorry for responding late, they're moving bases so it's hard to write. He'll be okay, Pen."

Penny nodded, leaning her head on her brother's shoulder. They were both scrawny. Bucky towered over them normally. They were at least a head or two below his height and she wondered if that would be the same with the experiment.

"He said it's supposed to enhance what we already have," Steve explained, as though reading her thoughts. "Bravery, loyalty, strength. That sort of thing."

"You're kind," she said simply. "That's why he picked you. You have a good heart. That'll only make you even more compassionate."

Steve smiled at her comment, pressing a gentle kiss to her head. "You're kind too," he said gently. "It's why Erskine's okay with you doing it. You're the sweetest person I know."

They were quiet for a moment. The shared silence between them filled with nerves and questions and fearful scenarios that neither of them dared to release from the minds, allowing their worries to settle like dust in the air.

"You're clumsy too," he said with a small chuckle. "Get ready to fall a lot more."

She laughed, shoving him lightly. "Okay, well, your sense of humor is terrible so it's only going to get worse."

"Ouch," he laughed, clutching his chest playfully. "You've wounded me. How will I recover?"

"Super soldier serum," Penny shrugged. "Apparently, it'll do wonders for that sort of thing."

He chuckled, nodding in agreement. He gave a sideways glance to her and held out an open palm. "Promise me you'll stick by me? With all of this..." He took a shaky breath. "I'm a little scared, Pen. I don't think I could do it without you."

She clasped her hand to his and interlocked their fingers. "Even if you decide to take over the world with your super awesome new powers, if we actually live through the experiment, then I promise to be there."

"Don't be the lost dog."

Penny inhaled sharply and squeezed his hand. It was a stupid saying, a mediocre catchphrase she and Steve had made up as kids. A stray puppy used to wander around their street when they were kids, and people would leave food out for it—their parents included. But anytime someone tried to give the dog a home, it would lash out. The more it lashed out, the more lonely it became. Less and less people fed the dog until one day, the dog bit a kid's hand. It was euthanized that same week.

Penny cried for nine days after the dog died. Steve cried for seven. Neither of them wanted to be that lonely. Neither of them wanted to be that apathetic and untrusting about their own life. And so at eight years old, they made a small vow to never be the lost dog. Never be a stray.

They'd always have each other, and on the slim, horrible circumstance that something would happen to the other — which Penny always vehemently denied would ever happen to the point of tears because the idea of an agonizing existence without her brother made her heart ache — they swore to find happiness some other way.

Never be the lost dog.

—

GETTING STRAPPED INTO A MACHINE by Howard Stark would have made Penny excited in a different situation.

She had a bit of a crush on the man. His flirtatious wink and comforting smile as he locked in her wrist straps did little to calm her erratically beating heart.

Before they strapped down her forehead and placed the mouth protector in between her lips, she took a glance to her brother, finding him doing the same thing.

His eyes were filled with determination and at his encouraging small smile, she allowed for same resolve to flood her.

She would be fine.

He would be fine.

They would be fine.

Everything would be perfectly fine.

"You ready, sweetheart?" Howard asked her softly, strapping her forehead under the restraints. They were for her own good. To allow the serum to work properly without her body involuntarily spasming.

She tried not to think about it too much, because that sounded absolutely horrible.

"You're married, right?" Penny blurted out. She's not sure why that was the first question to leave her lips, or why she hadn't asked for reassurance that of course he knew what he was doing and of course Erskine was a genius.

God forbid, she soothe her own nerves. Bucky's nature must have rubbed off on her. He'd flirt with anything on two legs.

Howard laughed, nodding. "I'm not," he winked. "You offering?"

A small smile tugged at her lips. "If this works out, wanna buy me dinner?"

A grin spread across his face. "Think of the first meal you want after we finish here, I'll take you."

"Yeah?" She grinned, a small laugh falling from her lips.

"You bet, sweetheart. Open up," he held up the mouth protector and she opened her mouth wide, breathing in sharply as he secured it. He placed a hand gently on her cheek. "You'll be fine. Just breathe."

Penny nodded the best she could under her restraint and he stepped back, closing the casing.

Fear seared through her heart as the wall encased her. This was it. No turning back now. She could hear her heart drumming loudly — was it echoing inside the chamber? — and her breath was picking up.

Tears stung at her eyes as anxiety roped around her heart, sinking into her bloodstream and dizzying her vision.

Closing her eyes, she tried to picture something else. Anywhere else. She'd rather be anywhere else. What if the serum killed her? What if she died today at twenty-three? What if —

Pain.

Indescribable, searing, soul-shattering, vein-splitting, bone-cracking, teeth-ripping pain struck her through every inch of her body.

A loud scream erupted from her throat, but she couldn't hear it over the sound of her own heartbeat in her ears.

Had it fallen from her chest? Was she dead? She felt dead. Or dying. Like she was dying. Was she dying?

It started in her forearms first, climbing through her body in a painstakingly slow manner. It simultaneously burned and chilled every nerve in her body, setting her limbs aflame and corroding her arteries.

She couldn't move.

She couldn't think.

She could only scream and feel in excruciating detail as her body rewrote its own composition, redefining her molecular biology.

And then, after hours — or was it days, weeks, months, years? She couldn't be sure — later, the casing opened slowly.

Breathing heavily, exhaustion flooded Penny. Howard was in front of her a few moments later, unstrapping her restraints. He smiled softly, cupping her cheek gently.

"You did it, sweetheart," he brushed back a piece of her sweaty hair. "You grew a couple inches. And you do not fit in that top anymore, but, hey, you're alive."

Penny breathed out a relieved laugh, looking down and noticing that, yes, her previously flat chest was quite a bit larger. Her arms were bigger too, muscled, toned out, her stomach was flatter, evened with hardened abs. She felt dizzy.

Stumbling out of the machine, she fell on Howard a bit. She was still a little bit shorter than him. That's good. She'd always liked being a big on the shorter side.

Howard caught her easily and she looked around, finding her a much larger and more muscular man —

"Holy cannoli, Steve?"

Steve looked her way, his gaze shifting from where Peggy Carter — the nice British officer who transferred them here to receive the serum — was touching his chest lightly.

Steve did a double take.

"Penny?"

A shocked laugh fell from them at the same time.

"You're freakishly tall," she pointed out with a grin. "You don't even — look at you!"

He nodded, the same boyish grin he'd always had taking over his features. "You're still freakishly annoying, good to know things never change."

Penny smiled in response and for a second, just a second, it felt like things would be okay.

And then a shot rang out. And then another.

Turning swiftly, Penny watched as Erskine fell to the ground, on his way over to the pair, and a gasp left her lips. Steve rushed to his side to help him, but Penny saw red. She moved past Howard, shoving him aside as Carter pulled out her gun, aiming at the assailant.

He was quick, too quick for her weapon, but not quick enough to escape Penny. Penny chased after him, out of the doors and onto the street. She heard someone else behind her, and then Steve's voice — much lower than before, that would certainly take some getting used to — then took a sharp left after the man.

She followed him down the busy streets of London, ignoring the stares as she ran, barefoot with nothing but a tank top and shorts. It was entirely inappropriate for a women of her age to be running around in another country in such a state, but she couldn't focus on that.

The man glanced back, dodging past a car and into an alleyway. They'd been running at least six minutes now — surely, surely the man had grown tired? — and he knocked a barrel over, which she easily jumped over.

He shot behind him aimlessly, missing her, and she rolled her eyes, picking up speed.

"Can you just stop running!" She shouted after him, gaining on him quickly. It felt strange not to be running out of breath. This man had to be getting tired. He was slowing, his fatigue catching up as the adrenaline failed him. Penny, on the other hand, was evenly-breathed, an excited grin on her face as she chased after him.

Then he turned a corner quickly and as she turned it, preparing to lunge at him, the bullet shot her through the stomach, piercing her abdomen.

"Fuck!" She shouted as he leaned against the wall, watching as she collapsed. Ignoring the pain, she stumbled forward, grasping onto his arm. "I'm so killing you."

"Hail HYDRA," the man sneered, biting down on something before foam filled his mouth and his eyes went wide and lifeless. He fell from her grasp and onto the floor.

Penny watched as he fell, observing him in silent shock for a few moments.

"Or you can kill yourself," she said finally. "That's cool too."

She looked down at her abdomen, the bullet still inside and grimaced in pain. She walked a bit further down the alley, searching for better lighting to get a better visual on the wound. If she could find the bullet, she could pull it out and her new super serum powers — talk about good timing — would heal her as good as new.

Blood spewed from the wound and she held her palm to keep it locked in place, breathing out shakily as she came across a set of train tracks. How far had this guy run? Where was she? Where was Steve? She hoped he'd had better luck with the other guy.

Poor Erskein.

Another step and pain flooded her.

Ouch. Poor Penny.

Squinting, she frowned when she stepped over the train tracks, finding what appeared to be a large cylinder object. It was copper and wrapped in some sort of wire...what was that thing?

And then, a flash of light darted from the object and over to her. It looked like a thousand little fireflies, watching her, observing her, before heading to her stomach.

She winced as they made contact, her eyes wide in confusion and fear as the wound began to slowly close, the bullet sliding from her abdomen. A tingling sensation on her skin and then it was gone.

Not even a scratch.

She blinked and the little fireflies were gone.

"What in the...?"

"You alright?" A voice called over to her. He sounded mid laugh, as though having paused to sound concerned. And he was British, that much she could tell. She liked his accent.

But then again, she liked all accents. She only had her slight Brooklyn accent. It was a bit thicker than Steve's, but he'd taken to covering his up. He didn't like to stand out. Now he was a super soldier, though, so look how well that turned out for him.

Penny jumped, looking around with wild eyes, her gaze settling on a man in a leather jacket and jeans. He had rather large ears and military-style shave on his head.

Penny nodded numbly. She must look a sight. Barefoot, hand bloodied, her stomach healed but covered in blood, wearing nothing but the tank top and shorts.

"Oh yeah," she said in a nonchalant voice. "Don't you ever come and stand on the train tracks wearing your undergarments and no shoes?"

He grinned. "All the time." He walked closer to her, grin dropping as concern replaced his face. "You alright? You're bleeding."

"Oh," Penny nodded, looking down. "Not —not anymore."

He observed her for a moment, walking closer and looking down at the injury. She felt a bit small then, despite being a few inches shorter than him. She should measure herself. She was probably just under 6'. He was watching her closely, looking over her body — as though she wasn't wearing close to nothing — intensely, as though figuring out a puzzle.

"Anyways," Penny took a step back. "I'm heading back. I — I left my brother over there." She paused, trying to remember how many turns she'd taken. "Somewhere. Do you live here? Can you point me in the direction of the hospital?"

His eyes snapped to hers. "Are you American?"

"No, what gave you that idea?"

"Your voice. You sound American."

"Have you ever met an American? I could be from London."

"No you can't."

"Yes I can."

"No you can't."

"Yes I can."

"No you can't."

"Why not?" She asked with a small pout. "Aside from the voice, I could totally fit in here."

"You are definitely from New York." He leaned back slightly and crossed him arms, jetting his chin in the air, "I can tell."

"How can you tell? Have you even been to New York?"

"Lots of times. Never in the right order though." He shrugged, turning and nodding his head for her to follow. 

"And what's that supposed to mean?"

He cocked his head to the side when he looked back at her, and his grin widened.

"Okay, big ears, listen here," she started, making him snort.

"Big ears? Straight to insults, yep, you're American."

"Maybe I'll take it as a compliment then. I like being American." Penny bragged.

He smirked at her. "For now, maybe."

"What's that supposed to mean?" She asked with a frown.

"Give it a couple centuries, America's a fun inside joke to the rest of the universe. Ha!" He laughed pointedly, although it didn't have an ill will behind it. It was more like he was laughing at a joke he's heard before and happened to remember.

"What does that even...?" She gave him an odd look. "Who even are you? Why am I following you?" She stopped walking, crossing her arms. She grimaced at the dried blood on her palms, wiping them against her arms, only to spread more blood.

The man sighed, coming closer and pulling something from his jacket. "I'm the Doctor," he said with a quick smile, taking her hand gently and wiping it with what seemed to be an already wet towel, though it was much thinner than one, and didn't feel like a towel at all.

"What is that?" Penny watched their hands as the blood came off. Her eyes widened in excitement. "Woah, how're you doing that?"

He watched her in mild amusement. "It's a towelette. Don't tell anyone." He winked at her and she let out a small laugh as he handed her another. "For your stomach."

"Thank you," she breathed out in awe. "I'm Penelope, by the way. Everyone calls me Penny."

"Penny," he repeated with a toothy grin. His teeth were crooked but the smile lit up his face. "Nice name, Penelope. Why'd you shorten it?"

Penny shrugged. "Just did. Couldn't say it when I was a kid and my best friend calls me lucky penny, so I guess it just stuck."

The Doctor nodded in acceptance. "You still need the hospital? What happened to you?" He looked down at her now clean stomach as she clutched the towelette in her hand.

"I know the way to where I'm going from the hospital. Just don't know how far away I am."

"Are you being vague on purpose?" He asked bluntly.

"I don't need to tell you everything. I just met you."

"Fair enough," he shrugged, turning and walking again. "I'm trying to find my friend. Seen anyone with blonde hair and a Union Jack shirt?"

Penny shook her head slowly. "No, sorry. You seen a shirtless guy running around like a chicken with its head cut off?"

He gave her an odd look. "Not today. Searching for one in particular?"

"My brother," she nodded. He nodded as if this was the most normal thing in the world, although as she was saying it, she realized how strange it actually seemed. "We were doing something for..." she trailed off, not knowing how much she could actually tell him. "Something. And we had to wear this to make it work. And..." she bit her lip, trying to think of the way to phrase it.

"Don't hurt yourself," he smirked at her, and gave light pat to her head. "Thinking can be difficult for some people."

"You'd know all about that, wouldn't you?"

He grinned as they walked, approaching a tall building dimly lit by the streetlights around them. She hasn't even noticed it had gotten dark. Worry twisted her stomach. Where was Steve? Was he okay?

"This is the hospital. Good thing I was going in this direction, otherwise you'd be on your own." She snorted at his words. "Nice meeting you, Penelope."

Penny nodded, watching as he walked towards the hospital. It was a straight left and then down three blocks, then a right. The building where the experiment had taken place. She just had to go back there.

But watching the Doctor enter the hospital, her eyebrows furrowed as her legs stopped her from moving. Something was telling her to follow him.

And so she did.

—

AND THATS IT AHHHH HOPE YOU GUYS LIKED IIITTTTT IM SO EXCITED SORRY about the delay it's been a busy hectic time for me but I'm pretty happy with this so buckle up because penny's so much fun and I'm SO excited for her and the Doctor.