Pepper had been Tony's PA for four years when she appears at her Malibu house one lunch time and finds a preteen dancing to Iron Maiden in the living room with a robot dog tight to her heels.

Though most things had stopped surprising her since she began working for Tony as his PA, but that sight definitely did.

Paperwork slipped from nerveless fingers when the preteen spotted her and stared at her with familiar dark eyes as dark curls messily fell around her golden tanned face.

For a brief moment they stood in silence, Jarvis having paused the music, before the girl let out a shriek of;

"NANNY!"

The sight of a maid-styled robot rolling out of the kitchen while waving a duster with a clear threat and shouting a war-cry was too much for Pepper's poor mind.

Pale green eyes rolled into the back of her head as her body slumped and hit the floor with a heavy thud.

"Oh my god, I didn't mean to kill her Tony, I swear!" A panicked high voice squeaked as the fog began to clear from Pepper's head though she kept her eyes closed.

"You didn't kill her." The calm voice of her boss replied. "She just fainted."

"I thought she was your PA?" The first voice lowered and was coloured with surprise. "How could seeing me cause her to faint?"

"I think it was Nanny's threat with the duster that did her in." Tony replied drily before a robotic female voice spoke a soft and chided apologies.

Pepper cracked open her eyes to see the girl from before peering down at her from behind the back of the white long couch that Tony must have laid her on, worry was clear on the girl's face and in her dark eyes as she peered anxiously into Pepper's eyes, the robot dog was cradled in her arms and the maid-style robot was peering over her shoulder with luminous blue eyes.

Up close, Pepper could see the diamond studs piercing her ears and the simple diamond white gold locket. Pieces of jewellery that Pepper had assumed were for Tony's newest girlfriend when she saw them in his office.

Tony stood on Pepper's other side, an amused smirk curling his lips with his hands tucked deeply in his pockets. But Pepper could see the worry in his dark eyes—not as strong as the girl's but still there.

"Good afternoon, Sleepy Beauty." Tony smirked down at her.

"What…?" Pepper couldn't bring her gaze from the girl's familiar dark eyes.

"Pepper this is Nattie," He gestured with one hand. "Nattie this is Pepper."

"Hi." Nattie piped up with a smile.

"Hey…" Pepper replied softly before she glanced back at Tony. "Is she…?"

"My sister?" Tony finished with raised eyebrows. "Why yes she is."

Pepper had been going to say daughter, but he had answered her question so she wasn't going to correct him. Though by the knowing light in his dark eyes made her think he knew and was amused by her thought.

"Right." She repeated that word a few times as she calmed herself before informing Tony of the paperwork he need to sign.

"Nanny, I'm sure my special girl should have her lunch." Tony spoke to the maid-robot that nodded her head before prodding Nattie towards the kitchen.

Something clicked in her mind when Tony said that, over the years Tony had mentioned to the press of a special girl waiting for him. Pepper, like the tabloids and everyone else, thought he meant a lover. He really meant his sister, which made Pepper reassess him in her mind as she watched him flick through the paperwork.

She had thought Tony was completely selfish and arrogant, thought he was the reckless spender and playboy that the tabloids painted him as. She was wrong. He obviously cared for his sister, the way he spoke to her had affection dripping from each word, though Pepper wondered why she was kept secret.

There had been no whispers that that Stark family had another child, never been any rumours of hidden daughter/sister. And yet, Pepper had seen her—seen her dance comfortably in torn jean shorts and a washed-out band t-shirt—and had heard her speak so comfortably with Tony.

When she surfaced from her thoughts she found Tony fixing her with an intense look—it was like he was reading her mind.

She hoped she made it clear that she wasn't going to blab about Nattie, and he must have seen it because he gave her a tight nod before pulling a pen from his pocket and sitting down to sign the paperwork.

Pepper spent the turn of the century in the Stark Mansion with Nattie while Tony was off at some party with Happy. The fourteen-year-old girl had complained that they didn't really start the 21st century until next year because than the numbers added up right and it was really the last year of 20th century, but had quieted down when the fireworks started.

In the four years of knowing Nattie, she could see how similar and different the siblings were in both looks and thinking.

Nattie's dark eyes were a deep dark chocolate brown while Tony's were slightly lighter with flecks of gold. There was natural golden highlights running through her curly brown hair while Tony's hair was completely brown, messy and looked like he never brushed it sometimes. Tony's skin was almost olive-toned while Nattie's was golden with a tan.

Both were genii, both could talk for hours and remembered everything, but Nattie was free with her emotions and words while Tony wore a mask of cockiness and calculated each of his words. Tony was bitter towards his father while Nattie only knew him as a picture and felt nothing for him.

Tony's mind was a whirlwind mathematic problems and concepts of new designs—only a few of those concepts were for new weapons. He invented things, brilliant things that made Pepper's head spin, and played with and built designs as an outlet for his energy—his brilliance.

Nattie was different than Tony, she could and had proven that she could keep up with his half-formed ideas and designs, and could build things on the same scale as Tony. But she didn't have the same interest in those things as Tony did, didn't have the same innate need to build things or take things apart to find out how things worked. Science wasn't her passion that was all Tony's.

Her passion was in art. She could draw and paint in such detail that it seemed like a photograph, sculpted dainty and beautiful things, and could paint complex geometric patterns that only Tony could make sense of.

Art kept her genius mind busy, could keep it focused on one thing instead of ninety different things, and she used it to express emotion and thoughts—an outlet for her energy. She could also loose herself in books, could put their words into images and paint them.

Her hobby, that Pepper totally blamed Tony for, was hacking. It was a hobby that she mostly shared with Jarvis as Tony was always getting Jarvis to hack into things. A.I ended up teaching Nattie a few tricks.

There was something the siblings shared. Their distrust for all governments, Tony kept an ear out for things through Jarvis while Nattie regularly hacked in government secure systems to keep an eye on this. Nattie could speed read through various reports in minutes, her mind able to pick up all the little detail—Pepper was half sure that Tony could do the same if he could focus all his mind on something.

That was something that Nattie regularly did, focus her whole mind on one thing while Tony let his ran wild.

Nattie was also patient while Tony was not, he had to keep moving while Nattie could focus all her mind inwards and remain completely still for hours. Jarvis had once timed that her to see how long, she had stayed still for three hours and only moved when she needed to go toilet.

Tony could be childish while Nattie could be strangely mature, but their roles could swap in an instant when left alone.

Tony loved attention, loved to party, but also loved to hole himself up. Nattie was more at home with robots than humans, didn't care about attention and didn't like the thought of going to the parties that Tony seemed to like. Like Tony, she also liked to hole herself up, listen to her music loud much like he did, and while he invented, she painted.