*A/N Poached from the What If…? series on Disney+ because my creativity is limited and Marvel's is not. Premise: Arianna is a high school junior when the Chitauri invade New York. How does Steve take it when she kisses him and he finds out she's still just a kid?

30 April 2012

Steve looked up from Fury's debriefing as he heard movement in the doorway just before a young woman strode into the 1940s decorated gym.

She was very beautiful with dark brown hair pulled up into a sleek ponytail to give him an unobstructed view of her sharp hazel eyes. She looked young, despite the file she held in her hands, but Steve knew instantly that this was a woman not to underestimate. The way she held herself and her build told him she was a fighter - and if he were to wager, a good one.

Seeing the direction of Steve's stare, Fury introduced, "Captain, meet agent Arianna Hart. Hart, you know who this is."

Steve nodded once in greeting. "Ma'am."

"Captain." Arianna smirked before she suddenly rose up on her toes and kissed him.

Steve froze, his muscles locking into place in shock. From beside him, he heard Fury sigh deeply as though he were unsurprised but not exactly pleased. Steve mentally made a note on that in a tiny corner of his mind; the rest of him was currently hyper aware of the softness of the woman's lips against his own. She was warm, warmer than he remembered. Not that he had much experience with women.

As suddenly as she'd kissed him, the woman lowered herself back onto her feet. Her eyes were dancing with mirth as she observed him while Steve just stared at her.

"You froze. I guess I won." Arianna announced with some satisfaction.

Steve had no idea what the agent was on about but Fury held a note of warning in his voice as he growled, "Hart..."

"No need to get your knickers in a twist, sir." Arianna rolled her eyes before saying to Steve, "Sorry if I surprised you, captain."

"Uh..." Steve wasn't sure how to respond. Was it normal in the twenty-first century for dames to just walk up and kiss men? From Fury's expression, Steve gathered not. But this was a completely new world to him - literally - so he couldn't be sure.

Noticing his discomfort, Arianna chuckled. "I promise I won't attack you again. Not unless you want me to."

She winked, clearly enjoying the way it made him even more uncomfortable. Clearing his throat, Steve tried to refocus.

"You here with a mission, ma'am?" He nodded to the file she still held in her hand, which he presumed was for him.

It seemed his assumption was correct as she handed him the file with an entertained smirk. Steve took the file, keeping it between him and the strange agent he wasn't sure he liked or disliked yet. Deciding Fury was a safer option, Steve glanced at the director.

"Trying to get me back in the world?"

"Trying to save it." Fury corrected.

Steve glanced back at Arianna, whose expression had suddenly closed off. The seriousness caught him off guard and in that moment, she suddenly looked far older than she should. He estimated she was twenty, maybe twenty-one; too young to be in an organization like SHIELD and far too young to have that look in her eyes that Steve recognized from his own army days. With a soft sigh as he mused on lost innocence, Steve opened the file to find a picture of an all-too familiar blue cube.

"Hydra's secret weapon." Steve murmured.

Sitting down, he flipped slowly through the papers as Fury explained, "Howard Stark fished that out of the ocean when he was looking for you."

Steve glanced up at Fury briefly before looking back at the picture of the Tesseract as Fury continued.

"He thought what we think: the Tesseract could be the key to unlimited sustainable energy. That's something the world sorely needs."

Steve closed the file. "Who took it from you?"

Fury took the file Steve held back out to him. "He's called Loki. He's… not from around here."

Steve noticed the dark look that flickered across Arianna's face at the name. He observed the agent while Fury continued briskly, "There's a lot we'll have to bring you up to speed on if you're in. The world has gotten even stranger than you already know."

Steve scoffed. "At this point, I doubt anything would surprise me."

Steve rose and started to gather his things but he paused when Fury offered, "Ten bucks says you're wrong." "You might want to rethink that bet, Captain."

Glancing back once at the director, Steve shrugged before he turned. Grabbing a punching bag, he tossed it over his shoulder while he carried his duffel in his other hand as he walked out.

"There's a debriefing package waiting for you back at your apartment." Fury called after him.

Steve just nodded curtly as he walked out, when Fury asked, "Is there anything you can tell us about the Tesseract that we ought to know now?"

"You should have left it in the ocean." Steve answered shortly, not looking back as he left without another word.

Arianna entered the helicarrier with Steve and Dr. Banner right behind her. The captain was staring around the ship in wonder when Fury joined them. Without a word, Steve handed the director a tenner that Fury accepted with a smirk. Arianna meanwhile joined Natasha in front of one of the security monitors.

"Fork it up." She announced as she held out a hand.

Wordlessly, Natasha pulled a twenty and placed it in Arianna's waiting hand. The redhead shook her head.

"I can't believe he froze." She muttered while Arianna pocketed the cash.

"You should have known better than to bet against Phil's protege." She grinned, pointing at herself for emphasis. Natasha rolled her eyes, but both agents quickly turned serious as they stared at the screen that was searching the globe for facial recognition matching Clint.

"Still no luck." Arianna murmured softly and Natasha's arms tightened across her chest.

"Well, he is the best there is."

They didn't bother exchanging meaningless assurances that they'd find him soon. Both of them knew too well that Clint wouldn't be found if he didn't want to be. Arianna stared at the screen where the picture of her father-figure stared back, looking far too grim. The Clint she knew was a jokester, even in the toughest of times. The formal SHIELD picture looked too much like how he looked under Loki's spell.

Arianna's hands tightened around the desk she was leaning against. She could only hope they'd find Loki soon and that it would be enough to free Clint.

Arianna strode into the lab behind Thor and Natasha, instantly on guard as she heard Steve say pointedly to Fury, "I was wrong, director. The world hasn't changed a bit."

Arianna glanced around quickly, noticing the antagonism on Bruce Banner, Tony Stark and Steve's faces as they faced Fury. Beside Tony was a screen showing the schematics for weapons that would be powered by the Tesseract. Realizing what had ticked Steve off, Arianna looked back in time to see Tony bring up her file onto the screen next.

"Yeah, we even still have child soldiers, apparently."

Steve glanced over before he did a double-take seeing Arianna's file on-screen. Specifically, her age, which Tony had very kindly zoomed in on.

"You're sixteen?" Steve demanded, whirling on Arianna. She crossed her arms defensively.

"Almost seventeen, actually."

"How is that any different? It's still wrong-" Steve said, shaking his head but Arianna cut through him.

"You signed up to be a German scientist's lab rat because you wanted to fight for your country. I think you're the last person to talk to me about morals, captain."

Steve's lips pressed into a hard line but it was Bruce who spoke next.

"Still, you're only in high school. What the hell are you doing in a place like this?" Bruce asked, looking appalled.

"Uh, killing people, apparently." Tony answered as he pulled up her history. "And lots of them, too if I'm reading this right. Tell me, kid, did you learn to talk or throw a knife first?"

"Did you learn to be an asshole before or after you started building weapons of mass destruction?" Arianna answered with sickly sweetness.

"I don't do that anymore." Tony countered and Arianna shrugged her shoulders.

"So? Doesn't change your past." She jerked her head pointedly at her file.

The pair engaged in a tense stare-off while Fury said forcefully, "Now, let's all stay calm-"

"So you can think of more lies, director?" Tony quipped. Bruce agreed sternly.

"Yeah, I think it's time we all talk truthfully."

"You wanna think about removing yourself from this environment, doctor?" Natasha suggested, noticing the darkness brewing in Bruce's eyes. The scientist scoffed.

"I was in Calcutta, I was pretty well removed."

"Loki's manipulating you." Natasha warned and Bruce gave her a pointed look.

"And you've been doing what exactly?"

Natasha's eyes narrowed. "You didn't come here because I bat my eyelashes at you."

"Yes, and I'm not leaving because suddenly you get a little twitchy." Bruce shot back before he pointed at the screen beside him where he still had the SHIELD schematics up.

"I'd like to know why SHIELD is using the Tesseract to build weapons of mass destruction."

Steve and Tony's agreement was obvious even if they didn't verbally voice it. Fury leveled a dark look around the room before he finally pointed at Thor.

"Because of him."

The god looked stunned. "Me?"

Fury nodded. "Last year earth had a visitor from another planet who had a grudge match that leveled a small town."

The rest of the room watched incredulously as Fury faced off against Thor.

"We learned that not only are we not alone, but we are hopelessly, hilariously, outgunned."

"My people want nothing but peace with your planet." Thor replied warningly but Fury countered, "But you're not the only people out there, are you? And, you're not the only threat."

He turned back to the room meaningfully.

"The world's filling up with people who can't be matched, they can't be controlled."

"Like you controlled the cube?" Steve asked contemptuously. Thor agreed with the captain.

"Your work with the Tesseract is what drew Loki to it, and his allies." Thor pointed out angrily. "It is the signal to all the realms that the earth is ready for a higher form of war."

"A higher form?" Steve interjected, brows furrowing at once but Fury spoke over him.

"You forced our hand. We had to come up with something-"

He gestured toward the weapons plans when Tony interrupted with a scoff, "Nuclear deterrent. `Cause that always calms everything right down."

"Remind me again how you made your fortune, Stark?" Fury shot back.

"I'm sure if he still made weapons, Stark would be neck deep-" Steve agreed but Tony interrupted.

"Wait, wait, hold on. How is this now about me?"

"I'm sorry, isn't everything?" Steve asked sarcastically at the same time Arianna said, "You're the one who always jockeys for centre stage, Stark, don't be shy now."

"I thought humans were more evolved than this." Thor sniffed disdainfully.

"Excuse me, did we come to your planet and blow stuff up?" Fury demanded of the god, who countered, "Did you always give your champions such mistrust?"

"Are you really that naïve?" Natasha cut into the brewing arguments. "SHIELD monitors potential threats-"

"Captain America is on threat potential watch list?" Bruce interjected with raised brows.

"We all are."

"Well, Sweet Sixteen here clearly deserves her place on that list, she's got more kills to her name than Rogers has successful conquests." Tony quipped.

"I swear to God, Stark, one more crack-" Steve warned and Tony called loudly, "Threating! I feel threatened!"

"I'll show you threats, Stark." Arianna snapped when Thor suddenly burst above all of their rising voices.

"You speak of control, yet you court chaos!"

"It's his M.O., isn't it?" Bruce interrupted. All eyes turned to the scientist in surprise as he continued scornfully, "I mean, what are we, a team? No, no, no. We're a chemical mixture that makes chaos. We're... we're a time-bomb."

"You need to step away." Fury said firmly, but Tony scoffed as he placed a casual hand on Steve's shoulder.

"Why shouldn't the guy let off a little steam?"

Steve hit the other man's hand away. "You know damn well why! Back off!"

Tony's eyes became steely and he said, no trace of his usual joking manner left, "Oh, I'm starting to want you to make me."

Steve matched him as he stood toe-to-toe with Tony. "Yeah. Big man in a suit of armor. Take that off, what are you?"

"Genius, billionaire, playboy, philanthropist." Tony listed.

"Oh, very mature." Arianna muttered while Steve glared at Tony, unimpressed.

"I know guys with none of that worth ten of you." Steve leveled a stern look at Tony. "Yeah, I've seen the footage. The only thing you really fight for is yourself. You're not the guy to make the sacrifice play, to lay down on a wire and let the other guy crawl over you."

"I think I would just cut the wire." Tony said casually. Steve smiled mirthlessly.

"Always a way out... You know, you may not be a threat, but you better stop pretending to be a hero."

That seemed to hit a nerve and Tony's tone was cold as he shot back, "A hero? Like you?"

He stared Steve down and snapped, "You're a laboratory experiment, Rogers. Everything special about you came out of a bottle!"

Steve jerked slightly while Arianna's eyes widened and then narrowed at Tony's low blow. But the captain swiftly recovered and he growled, "Put on the suit, let's go a few rounds."

Thor started laughing. "You people are so petty... and tiny."

"And you're a moron who relies on brute strength to solve everything." Arianna returned sharply.

Thor immediately stopped laughing, but Bruce stopped the next brewing argument as he let out a weary sigh.

"Yeah, this is a team."

"Agent Romanoff," Fury ordered. "Would you escort Dr. Banner back to his-"

"Where?" Bruce demanded, gesturing toward the door sarcastically. "You rented my room."

"The cell was just in case-" Fury began, trying to placate the scientist but Bruce was done listening.

"In case you needed to kill me, but you can't. I know, I tried."

Silence followed the man's unexpected confession. Anger melted to pity as understanding dawned on each person, but Bruce didn't want their pity. He wanted them to understand.

"I got low. I didn't see an end, so I put a bullet in my mouth and the other guy spit it out. So I moved on. I focused on helping other people. I was good, until you," he glared at Natasha and Fury, "dragged me back into this freak show and put everyone here at risk."

His voice began to crack as he became agitated, reaching behind himself as he addressed Natasha directly.

"You wanna know my secret, Agent Romanoff? You wanna know how I stay calm?"

Arianna saw where Bruce's hand was headed and her hand instantly went to the gun at her hip. Next to her, Fury and Natasha did the same as they saw the same thing she had, but Steve quickly called loudly, "Doctor Banner."

Bruce glared at him but Steve was unfazed by that as he said warningly, "Put down the scepter."

Bruce looked at his hand in surprise, only now aware that he'd grabbed the staff. The tension in the room was thicker than ever, when suddenly a computer in the far corner of the room beeped. They all glanced at it as Banner carefully put the scepter down.

"Got it. Sorry, kids." Bruce added sarcastically as he walked to the computer. "You don't get to see my little party trick after all."

"Located the Tesseract?" Thor questioned, while Tony said quickly with a pointed look at Steve, "I can get there faster."

"Look, all of us-" Steve started in exasperation but he was interrupted as Thor said to Tony sternly, "The Tesseract belongs on Asgard, no human is a match for it."

Tony just shrugged, starting to leave the room anyway. But Steve had had enough and he grabbed Tony's arm.

"You're not going alone!"

Tony wrenched his arm away. "You gonna stop me?"

"Oh, for the love of- And you say I'm too young!" Arianna exploded. Steve whirled on her.

"You are! And you proved it the first time we met!"

"You didn't look like you were complaining, old man." Arianna snapped while Tony's brows shot up and Steve grit his teeth.

"You're the one who kissed me, agent Hart."

"Wow, Captain Rogers, hitting on young girls?" Tony taunted. "If you're like a hundred, are you still a pedophile or is there a new name for people like you?"

Steve glared at the shorter man.

"Put on the suit, let's see if you're still so tough." He growled.

"I think we should name it the Roger-syndrome." Tony mocked and Steve snarled through grit teeth, "Put on the suit."

"You guys-" Natasha started but didn't finish.

An almighty boom rocked the entire helicarrier and one side of the lab exploded as the explosion's after wave shot through their section of the ship. Thor and Fury were tossed to the side of the lab while by the windows, Bruce and Natasha were sent flying out the glass window before they fell down several floors below. On the other side, Steve grabbed Arianna instinctively as they were all thrown back as a result, the pair crashing down beside Tony while debris rained down on them.

Groaning Arianna lifted her head as Steve pushed himself up and surveyed the damage before looking over at Tony.

"Put on the suit." He advised.

"Yep!" Tony agreed as the trio hauled themselves to their feet, their argument put aside for the moment as they raced out of the destroyed lab.

Their argument turned out to be put aside indefinitely, as the next day found the newly formed Avengers fighting side by side against an entire army from space.

Even years later, Arianna had no idea how she had ended up where she was. All she'd done was take on a job as an agent at SHIELD. She'd signed on for danger, sure. But not even in her wildest dreams had she ever imagined she would be battling against an alien army with Captain America, a Norse god, the Hulk and Iron Man. If she'd had any idea this was where her future was headed, she wouldn't have chosen knives as her signature weapon. A bazooka that never ran out of bullets would be serving her much better at the current moment.

Arianna threw her last knife, embedding it into the neck of a Chitauri that was about to sneak up on Steve. He meanwhile threw his shield, knocking down the three aliens that were trying to sneak an attack on Arianna. Back to back, the pair stood, trying to catch their breath as Arianna finally drew her pistols. She didn't want to think what would happen if she ran out of bullets too; probably, she'd have to steal one of the Chitauri's weapons.

A shadow passed overhead and Arianna glanced up to see Thor joining them, the god sending a bolt of lightning down on the Chitauri. Looking back down, Arianna saw a Chitauri aiming at Steve.

"Steve!" Arianna yelled, his given name slipping from her lips for the first time.

Steve whirled around at her shout; he saw the danger too late. But before the blast could hit him, something crashed into his side. Steve stumbled before he turned in alarm as he heard something smack into the nearby car.

"Arianna!" Steve shouted fearfully, rushing to check on the young agent as she fell to the ground while Thor took out the Chitauri that had attacked them.

Arianna gasped from where she was sprawled beside the car, clutching her stomach in pain from the blast. Steve knelt down beside her, scanning her quickly. She was likely in a lot of pain but nothing fatal, he was relieved to see. Steve bent down to help Arianna get back to her feet and she grimaced as her leg gave out slightly beneath her.

"You okay?" Steve asked worriedly as he caught and then steadied her as Arianna regained her balance.

"Fine, fine." She muttered, just as Thor came flying down.

"You two ready for another bout?" Thor questioned although his concerned blue eyes remained on Arianna.

"What, you afraid a little human's going to beat you?" Arianna joked although it fell a little flat as she tried and failed to stand straight.

Steve continued to hold her, afraid she was going to fall over as he took in her exhausted countenance. Thor looked as worried but as more Chitauri advanced toward them, he flew off to meet them.

"I think you need to stay down." Steve advised Arianna, but she shook her head.

"I'm winded and sore, not dead." She answered shortly.

"Arianna-" He held her shoulder tightly and Arianna glared up at him.

"Don't talk to me like I'm a kid." She warned. Steve shook his head.

"I'm not." His face was grim, the image of the captain he was. "But you're hurt and no matter what your age, if you're going to get killed, I can't let you go back out there."

Arianna stared back at Steve with serious hazel eyes, no trace of the joking teen he'd first met left in the face that had seen far too much far too soon.

"I get that, Steve. But this is war. And it's not your call to make. I can fight - so I'll fight."

Steve gave her another hard look, searching her gaze. What he saw surprised him. It was like he was staring into a mirror. For a moment, as he gazed into Arianna's hazel eyes, he saw not the woman but himself as he'd stood in the Stark Expo seventy years ago. To the world, puny; but inside, determined and with a fiery gaze that wouldn't stay down. Steve finally nodded and he let her go.

"Okay. But stay close."

Arianna nodded. Together, they leapt back into battle. Arianna had just shot down another Chitauri when Natasha's voice suddenly came through their comms.

"I can close it! Can anybody hear me? I can shut the portal down!"

"Do it!" Steve bellowed, but Tony cut in sharply.

"No, wait!"

"No time!" Arianna yelled as she barely dodged a Chitauri that had gotten too close while she was otherwise occupied.

She shot it in the head as Steve agreed, "Stark, these things are still coming!"

"I got a nuke coming in. It's gonna blow in less than a minute."

Arianna's blood ran cold at Tony's explanation. The council. Only the council could authorize this.

"And I know just where to put it."

At first, Arianna frowned in confusion at Tony's words. Then, she looked up with Steve at the portal as realization hit them and turned to horror.

"Stark, you know that's a one-way trip?" Steve said tightly.

Tony didn't say anything for a moment before he said in a too light tone, "Save the rest for return, J."

Arianna turned as her head was almost lopped off and she killed another Chitauri before she looked back up at the sky as Tony disappeared through the portal, carrying a nuke between his hands. Her heart dropped like a stone, especially as suddenly all the Chitauri around them collapsed, deactivated when the nuclear bomb had exploded and taken out the control ship. And most likely Tony Stark.

Steve stepped up beside Arianna, staring up at the portal with a tight jaw as they waited for any sign of Tony. But there was nothing. Thor arrived beside the pair just as there was a faint booming noise and a supernova started heading towards the portal gate. Steve and Thor exchanged looks, and Thor gave a short nod to the captain.

"Close it." Steve ordered quietly into his earpiece.

Arianna sucked in a sharp breath as the beam from the Tesseract faltered when Natasha closed it, before it disappeared. The portal started to shut and Arianna shook her head.

"He was a hero after all." She murmured. Steve glanced at her before looking back at the sky… just as a small figure fell through the closing portal.

Arianna's eyes widened while Steve murmured in disbelief, "Son of a gun."

But it was too soon to celebrate.

"Is his suit working?" Arianna asked as Tony continued to free-fall. Steve tensed while Thor shook his head.

"He's not slowing down." The god muttered, starting to swing his Mjolnir as he readied to go catch Tony.

But before he could, there was an almighty roar and the Hulk suddenly appeared out of nowhere, jumping through air and catching the falling man. Arianna watched in disbelief as the giant green being slid down the side of a building before leaping to land safely on the ground with Tony cradled safely in his arm.

"Unbelievable." Arianna murmured as she ran with Steve and Thor to where the Hulk was gently laying Tony down on the ground.

He remained unmoving even as Thor turned him over and pulled off his helmet. Steve bent to check Tony's vitals while Arianna stood over him tensely.

"What's going on down there?" Clint asked in her ear and Arianna shook her head.

"I think Stark's dead." She murmured, a surprising grief starting to build in her chest for the billionaire former playboy when Steve pulled away from Tony's dim arc reactor dejectedly.

But the Hulk wasn't going to have that. He roared right in Tony's face, and they all jumped as Tony gasped back to life, his eyes flying open and staring around wildly. Steve's face broke into a disbelieving smile while Arianna's face blanked in stunned surprise. The Hulk roared again in triumph, beating its chest proudly.

"What the hell?" Tony gasped, and Clint echoed him in Arianna's ear.

"Stark's back from the dead." Arianna answered numbly just as Tony's eyes landed on them.

"Please tell me nobody kissed me." Tony demanded, his eyes fixing on Arianna. "Especially not you, maybe in a few years if you weren't so scary, but I don't need a child molester charge or something filed against me."

And he really was back. Arianna shook her head while Steve breathed a laugh as he sat back on his hunches.

"We won." He mumbled, still not completely able to believe it.

Tony glanced around before he said lightly, "Alright. Hey. Alright. Good job, guys. And girl."

He nodded at Arianna who looked torn between punching him or actually kissing him. She started to lean toward the former as Tony continued to ramble.

"Let's just not come in tomorrow. Let's just take a day." He groaned in pain before adding randomly, "Have you ever tried shawarma?"

Steve had to chuckle as he stared down at Tony, his blue eyes bright with emotion as Tony continued, "There's a shawarma joint about two blocks from here. I don't know what it is, but I wanna try it."

Steve chuckled despite himself at Tony's absurdity. Arianna too was laughing at last as she fell back against the supersoldier wearily. The hours of fighting were catching up to them but in that moment, an odd sense of peace settled over the Avengers. And as Steve let himself finally relax, he glanced at the brunette beside him with new eyes.

She was still too young. But as Steve felt the steady rise and fall of her shoulders as she breathed while still leaning against his shoulder, he couldn't help but wonder. When she was older… if she was like she was now… Well. Who knew what the future would bring then?

Suddenly, Arianna shot upright.

"Sh*t!"

"Language." Steve chided softly but no one heard him as Arianna groaned loudly and buried her hands in her face.

"What's wrong with her?" Thor questioned. Tony shrugged.

"Maybe she's got her period?" He suggested and Steve almost hit the other man. But Arianna thankfully didn't hear him as she lifted her head.

"It's Monday!" Arianna moaned.

Before anyone could ask, she wailed. "I missed my final exam!"