Prompt: Penny and Peter coexisting.

Penny woke up with a scream caught in her throat, fingers fisted in the sheets, and she had to force her hands to relax before the ripped. Taking a deep breath, she reached up to her face and was almost surprised to find wetness on her cheeks. Looking around her bedroom, she waiting the split second for her eyes to adjust to the darkness. Taking deep, gasping breaths, she closed her eyes and tried to count. To do the breathing exercises that Tony had taught her.

That her dad had taught her.

It had been three years since he'd adopted her from that group home, the place where she'd been left after three failed foster families. The place where one of the nuns had helped her hide her powers. Had, as a mutant herself, taught her control. And then, one day, while on her way home from the Catholic school she'd attended her whole life, her senses had gone off. The spine-tingling sensation that warned her of danger had stopped her in her tracks, and she'd turned just in time to see the cars...to see the green car speeding toward the black one sitting at a stoplight, as if with intent, and she'd moved on instinct.

That memory was in flashes. Five long, loping steps into the road. A spin, hands held out as she'd braced herself between the driver's door and the hood of the green car. The impact, throwing her back against the black car, not hurting her but cracking the window. The men getting out of the back seat of the green car with guns drawn.

And the hand on her shoulder, pushing her gently out of the way and behind the red Iron Man suit. And that's when she'd realized that the car belonged to Tony Stark.

She had been ten years old.

While Iron Man had fought the men, bullets flying and bouncing off his suit, Penny had turned and fled, cursing herself for being so stupid. Why had she stepped in? Already, eyes had been following her, and she'd cut through alleys and side streets, racing back to the group home and going immediately to the room she'd shared with three other girls, the four of them sleeping in bunk beds. There she'd hidden out whenever possible, trying to never leave the house lest Iron Man find her and...well, she hadn't known what he'd do. All she'd known that she was a ten year old mutant trying to hide her powers, the ones she'd had for as long as she remembered. And her foster families had all signed NDA's...had all been so scared of her that they'd refused to touch her by the time she was sent back to the group home...refused to hug her or ruffle her hair like they did their other kids.

The nun at the group home, Sister Laura, had been worried about her. She'd asked over and over what was wrong, and had hugged her and sat with her on the sofa on movie nights, but still, Penny had withdrawn more and more until Tony Stark had showed up at the group home, asking about her.

And then life had seemed to spin out of control. First, he'd showed up in the morning, wanting to talk. She'd refused, sitting on the very corner of her bed, face hidden in her knees, and no matter how much Sister Laura had assured her that it was okay, Penny had refused to come downstairs and see him. He'd come back the next day too, and this time, he'd been sitting in the living room when she'd returned from school, he and Sister Laura chatting on the sofa and having slices of her famous apple cake. Penny had frozen in the doorway, heart pounding, but Sister Laura had smiled at her gently. "Penny, Mr. Stark would like to talk to you. Why don't the two of you go into the recreation room?"

Penny hadn't known how to say no. How to refuse, not with him right there. So she'd nodded, head down, hands clasped in front of her as she'd led the superhero billionaire down the hallway and into the recreation room, which was full of card tables, and was where they had movie nights. The man brought a plate with him, and she had assumed that it was his slice of cake, but when she'd sat down at one of the tables, he'd placed it in front of her, along with the fork, before taking his own seat.

"Sister Laura told me that it was your favorite."

Penny had muttered her thanks, but hadn't touched the cake. After a moment, the man had cleared his throat. "So...I wanted to thank you." She'd lifted her eyes, hesitant, and he'd continued on. "You saved my life, kid. And I've gotta admit, you just about gave me a heart attack. I'm glad you're alright." Penny hadn't dared speak. Hadn't known what to say. But he'd gone on. "So...for the thanking part. I went ahead and set up a college fund for you, so hopefully that will help. I checked out your grades...keep it up and you could get into any school you wanted."

"You didn't have to do that," Penny had finally choked out, eyes wide. He'd just smiled a little.

"Not a problem, kid. Least I can do. So...you've got super powers, huh. That's something."

She'd shrugged, feeling a bit more at ease thanks to his casual tone. "It's why I'm here." He'd furrowed his brow. "No one wants a mutant kid."

He'd nodded, lips pressed together, eyes lowering. "Yeah. That sucks, kid."

Penny had just shrugged again. "I'm too old anyway. People want babies. Normal babies."

"And you weren't ever a normal baby?"

She's shaken her head. Normally, adults had gotten uncomfortable when she'd told them this. And Sister Laura had always seemed sad, assuring her that she was loved by herself and loved by the other sisters and loved by God. And that had been nice. But this, an adult looking at her seriously, without pity, was better. "No. My mom was sick when she had me. I don't know why. But I was born like this and my mom died."

"Yeah? Well...what about this place. It doesn't seem too bad. A little outdated…" He'd glanced over at the TV on a cart, wrinkling his nose a little.

"It's fine. Sister Laura is really nice. And church isn't so bad."

"How many other kids live here?"

"Seven. Sometimes more stay for a little while. We're the ones no one else wanted."

Penny didn't know what made Tony Stark come back for her. What made him set up a room in his tower and go through all the legal proceedings to adopt her. In fact, she still didn't know. She'd asked, on nights when she'd woken up from the nightmares she'd had for as long as she could remember. And, ever the insomniac, Tony had led her to the kitchen and had made her cups of hot chocolate every time, stirring in real chocolate syrup into milk instead of the chocolate powder that Sister Laura had alway bought at the group home...the powder that had usually lasted for about three days before they'd run out.

On that first early morning when Penny had sat on her stool and Tony had served her hot chocolate and himself coffee, Tony had just shrugged. "You needed a home. I had the space. I figured...why not give it a go. I'm a big believer in gut feelings."

It had taken a long time for him to feel like her father. At first, he'd been kind of like a strange roommate...like one of the nuns except...a man. And...more into building things. He'd invited her down into his lab, teaching her all about the Iron Man armor, and she'd taken to his lessons on engineering and the various other branches of science immediately. She'd loved it...had spent every second she could down there with him. And eventually, over hundreds of meals and movie nights and visits to the group home, over plenty of cups of hot chocolate and nights spent helping her with her homework and the countless times he'd sat with her in her room, tentatively touching her shoulder after a nightmare, then pulling her into his arms and letting her cling to him, he had become her dad.

Penny checked the time, rubbing a hand over her eyes and dropping back into bed. It was only 3:30. On a Saturday morning. This was the morning that her dad's new internship started. It was a partnership with their local STEM school, Midtown High, which she also attended. He had assured her that she could also do the internship...that he'd have plenty of time to work with her in the lab. That promise had been sealed with a kiss to her hair and a tight hug, his arm thrown around her shoulders the day he'd told her about it.

He'd told her that the intern's name was Peter Parker, that he'd also been adopted, and had taken the name of his adoptive family, just like she had. Other than that, he apparently hadn't tried to find out much about him. Penny hadn't recognized the name, but apparently he was new...a transfer student, and since they were only a couple of weeks into freshman year, it made sense that she hadn't met him yet. After all, Midtown High was huge.

And strange.

No...not strange. Just...something had made her uneasy lately. The nightmares, the ones she'd been having for as long as she remembered, had only gotten more frequent, and her senses had been going haywire. Not her danger sense...she didn't feel like she was in danger. But something else...another sense, had been making it almost impossible to focus.

She hadn't talked to her dad about it. Instead, she'd spent more time than usual in her room and in the lab, pretending to be engrossed in homework. And she was sure that her dad was going to talk to her about it any day now. But she just felt...off. Strange. Closing her eyes, Penny tried to forget about the nightmare. Tried not to think about the feeling of reaching for something...of running and running through a building full of twists and turns, or through a forest with branches lashing out for her. Both were filled with spiders. Both were pitch black and dangerous. But she was always looking for something. Always desperate to find it.

But she never did.

In the end, the dream would always end abruptly, with her falling through a hole in the ground, or turning a corner to find something waiting for her. Something dark with sharp teeth and claws straight out of a horror movie. And every time, she would wake with a scream.

She must have fallen asleep, because Penny jerked awake to a room flooded with light from the curtains she must have forgotten to close. She looked around her room, breathing heavily for some reason, heart pounding as her senses flared up, just like they had every day at Midtown. She threw her legs over the side of the bed, grabbing her dad's MIT sweatshirt that she'd stolen the night before and a pair of sweatpants, figuring that she wasn't going to see anyone except her dad and Pepper...and maybe Rhodey. Probably not the new intern. He was only coming by for a few hours that morning to look around the lab and talk to her dad.

As Penny headed for the kitchen, her senses made it impossible to focus. Impossible to make herself walk to the freezer to find the frozen waffles she loved best for breakfast. Instead, for some reason, she was walking toward the elevator. It was almost ten thirty...the new intern would be in the lab. Peter Parker would be down there with her father. And it wasn't her internship. She had no right to barge in. Her dad hadn't forbidden it...but she was sure she wasn't supposed to just show up.

But she got into the elevator. She pressed the button for the lab, heart in her throat. Something was wrong. Something was happening. Her body was moving without her consent, her brain just along for the ride, and then the elevator was moving, her stomach seeming to hover as though she were on a roller coaster. It was just the lab! Just an internship! She was sure Peter Parker was totally normal and her dad was going to let her have an internship too because, in his words, she'd earned one thanks to her grades and extracurriculars, just like Peter Parker had. That her application would have been just as impressive.

"And besides," he'd said with a grin, "shouldn't being Iron Man's kid come with some perks?"

She'd laughed at the time but now she felt like she might throw up. But why? It was fine. It was just the lab! It was just a kid from her school in the lab with her dad doing his internship!

When she stepped out of the elevator, her senses exploded. Her whole body felt like it was lit up, like the Christmas tree Pepper always put up. Penny felt like that tree the moment they finally plugged it in, watching the lights that covered the tree burst into color. And without knowing where she was going, she walked straight into the room, then froze when she saw them.

The boy standing beside her dad stiffened, a hand moving immediately to the back to his neck. Her dad glanced down at him, both of their backs to her, until Peter spun around, his brown eyes huge as they met hers. Penny was vaguely aware of her father turning too...of his soft, concerned voice greeting her. Asking her if anything was wrong. Of his footsteps as he approached her, and the tear that suddenly ran down her cheek, leaving a cold trail on her face. But all she could focus on was him. Peter. Peter Parker. Every cell in her body seemed to reach out to him, to know him, and by the look on his face, he felt it too.

Together, they opened their mouths, their soft words melting together in the silent lab.

"You're like me."

"What?" Her dad's voice nearly brought her out of it as she stepped toward Peter, him mirroring the action, the two of them meeting in the middle of the room. "Pen? Kiddo, what's going on?" he asked with what sounded like a nervous laugh. "Do you two know each other?"

When they finally met, Penny lifted her hand, not knowing why until he did the same, the two of them moving in unison, hands touching and sticking firm. He was like her. Sticky. Strong. A mutant. Just like her. The dream came to her then, a nightmare she'd had her entire life. Running through a maze. Running through a building. Running and running and trying to find something she could never reach.

And that's when she realized that she'd finally found it.

She'd finally found him.

"Yeah," Peter choked out, and it occurred to Penny that she'd forgotten the question. "Yeah...I think we do."

"He's like me," Penny reiterated, still not looking at her father who moved to join them, his hand on her shoulder. "I...I know him."

She did. She knew him. Every cell in her body knew him. He was what she'd been looking for without even realizing it. Peter.

"When you say 'like you,'" her dad started, trailing off.

"He's a mutant too. Like me."

It didn't take long for Friday to run the DNA, for the AI to announce what Penny had known from the moment she'd laid eyes on him. Twins. And as Tony instructed Friday to find out everything she could about the two of them, about their parents, and specifically their mother, Penny threw her arms around her brother who held her close, both of them squeezing hard enough to hurt a regular person, and felt her senses go calm for the first time in weeks.