"I have never met anyone more selfish and stubborn than you!"

"Funny, I was about to say the same thing about you!"

It had started as a sparring match. How had it gotten to this point?

Natasha gnashed her teeth, swinging at her sister in a blind rage. "How am I the selfish one?! Never once in my life have I needed anyone or anything! I take care of myself while you hang off of me like some sort of lost puppy! I didn't ask for this; you were just thrust upon me!"

Yelena lashed out and struck Natasha's jaw, effectively throwing her off balance in a temporary haze. "I didn't ask for my brain to be put through a blender and be spit back out a different person! I didn't ask to be the monster kids fear live under their beds! And I certainly never asked to be your pet." Yelena spat the last word with venom even a spider would fear. "While you partied with the superheroes, I was fighting for my life. Where's the Black Widow when you need one, eh? She's probably off living the Avengers tower life with her so-called family. Must be nice."

"The Avengers?" Natasha's eyes darkened as she backed Yelena up to the corner of the ring.

Yelena sunk under her gaze, quickly transitioning into a scared kid. This was the Black Widow. Natasha Romanoff was nowhere to be found.

Natasha leaned in close to Yelena, boring holes into her soul. "They were there for me. They were the family I never had. They got me out of that place, and I never looked back, not even once. The Avengers were my home now. The most real thing I ever had, was them."

After a few moments of letting her words sink in, Yelena's blood began boiling with rage. Her fists clenched tight, and before either of them knew what was happening, they were on the ground, Yelena straddling the Widow as she prepared to finish the fight once and for all.

"Hey!" Clint ran over to the ring and hopped over ropes, pulling Yelena off Natasha with one swift tug, dragging her back to put some distance between the women. "What's going on here? Why are you trying to kill each other?"

Natasha wiped her face with the back of her hand, brushing some blood from her jaw. "Ask her. She started it."

"You started it 20 years ago, you little-"

"Knock it off, both of you!" Clint held Yelena back by the shoulder as she tried to continue the fight. "You're acting like children! Do you need a time-out or something, because I am not beneath that."

Yelena jerked from the man's grasp angrily but didn't try and move any closer to her sister. "I'm not your kid, Clinton. You can't tell me what to do."

Clint gave her what could only be described as a dad look. "Go cool off. I've got this handled."

Yelena stepped closer to him, a bitter smile gracing her lips, effectively startling Barton. "It's your fault, you know. You took her away from me. Congratulations." Yelena bowed with a sarcastic flourish. "You won. I hope you're happy with yourself." She then sulked off, leaving the best friends to hash it out. She didn't want to hang out with Clint anyway.

Clint watched her leave, wondering what could've possibly happened between them to lead to this kind of hostility. Usual he and Yelena got along great. He shook his head to clear it. One at a time. "Now you." Clint held his hand out, and Natasha took it with an eye roll.

"You didn't need to intervene. I had it under control, you know," the assassin assured as her friend brought her to her feet.

"Uh-huh, sure." Hawkeye widened his stance and crossed his arms. "You two were out for blood. And-" Clint gestured vaguely to Natasha's injury. "It looks like she won."

Natasha scoffed, the fire in her eyes reigniting when she thought about the younger woman's face. "She gives in too easily. Maybe one day she'll learn to control that temper of hers."

"Nat." Clint tilted his head and looked at his best friend with concern. "We're thinking of the same person, right? The kid who loves you more than anything? Your weak spot?"

Natasha laughed humorlessly, smiling an empty grin. "That's impossible. I don't have a weak spot."

Clint breathed out and shifted uncomfortably. He barely even recognized the person in front of him. He might even go so far as to compare this to the Natasha he knew when he was sent to kill her. "Okay, then let's start from the beginning. What led to this?"

Natasha shrugged. "We were just sparring. Then she went off on me for no reason."

"No reason, huh?" Clint shook his head. He knew Natasha better than most people. But this was new to him. Natasha always put others' feelings first, but that was not what she was doing now. Yelena must've struck a deep nerve. "What did she say to you?"

"She implied that I was living the good life with the Avengers while she suffered in the red room. A place I was sure we destroyed. It's not my fault I didn't know-!"

Clint waved his hands around to stop her. "Wait, wait, wait. Slow down."

Natasha's shoulders dropped in a rare act of submissiveness.

"I know Yelena. She wouldn't attack you without being pushed first. What did you say to her?"

Natasha swallowed and averted her gaze, thinking about their conversation. She was so angry she hadn't even thought about what she had said back. "I... I called her a lost puppy."

"And?" Clint pushed, knowing there had to be more than just that minor insult.

Suddenly guilt weighed heavy on Natasha's chest. Everything came flooding back all at once, and she finally realized what she had done. "And... That I didn't ask to have her thrust back into my life..."

Clint hummed and nodded absently. "Yep, that'll do it... Nat, you mean the world to Yelena. I'm sure the mere implication of you not wanting her was enough to earn you a bloody jaw. But it was more than that, wasn't it? What made her jump on you?"

Natasha growled lightly. She was the Avenger known for her interrogation techniques, but Clint was just as good as she was. The others underestimated his abilities. "I told her that the Avengers were my family. That you guys looked out for me. That I never looked back after I joined SHIELD."

"Is that true? Did you look back?"

The redhead slowly shook her head, chewing on her lower lip. "I thought about her all the time. I could only hope that she was living a normal life somewhere safe."

"Then tell her that." Clint stood a little taller and arched his eyebrow. "She looks up to you, Natasha. You're her home. And I'm sure hearing you talk about us and inferring that your family before us meant nothing to you, broke her heart. She reacts with violence before her true feelings show. She's just a kid, Nat. Yelena needs you to want her. She's been through enough already, and so have you."

Natasha bowed her head, refusing to cry. She wouldn't cry. She didn't deserve the emotional release after everything she had said to her little sister.

"So." Hawkeye lowered his arms to his side and cocked his head. "Shall I patch you up before you go apologize to the little firecracker?"

Natasha chuckled and nodded once. "Thanks, Clint. It's a good thing you showed up."

Clint shrugged, a slight smirk pulling at his lips. "Ah, well. Every team needs at least one leveled-headed person on it."

xxx

Meanwhile...

Yelena walked out of the training room, her stomping echoing in the halls of the compound. Natasha's words danced around in her head, effectively keeping her in a pissed-off mood. Who gave her the right to talk to her like that? Natasha had never met anyone more selfish than her? Yeah, right.

Yelena wasn't sure where she was going; her feet just kept carrying her forward. Eventually, she found herself in Tony's lab, standing off a ways so she could watch the master at work. There was just something about seeing a genius in his natural habitat.

After a few minutes of allowing the younger Romanoff to watch him work, Tony stood up straighter and wiped some grease from his hands with a towel. "Alright, kid, what's gotten you all sad and brooding? I know you're down here for more than just watching this old man tinker."

Yelena smirked slightly. Oh, how she loved messing with a Stark. "What can I say, your ego fills the room with such an interesting aura that I just had to come down and experience it for myself."

"I'm not like that anymore." Tony pinched his fingers together with a small space in between. "I'm a little more humble now."

Yelena hummed gave a dry nod. "Right, duh. Tony got some character development."

"That's right." Tony leaned on the edge of a table and jerked his head to the side to call the blonde over.

Yelena sighed heavily and joined him, making sure there was a comfortable distance between them.

"Do I need to scare someone off for you? A bully perhaps," Tony asked in all seriousness, ready to take care of the issue no questions asked.

"Not unless you'd actually grow a pair. I doubt even the almighty Iron Man would dare go against the Black Widow."

Tony raised his eyebrows. "Natasha got you like this? Are you sure?"

"You think I wouldn't know, Stark?" Yelena challenged, her head tipping back with dominance.

"I don't doubt you, kid," Tony replied easily, resting his forearms on his workstation. "What happened?"

"It's nothing..."

Tony chuckled as he looked at the young woman next to him. When he met her, it was no question that she was Natasha's little sister. He thought nothing could ever get between them. Tony had seen too many familiar relationships die, and he would not let this one end up like the rest of them. "If it were nothing, you wouldn't be in my lab. Come on, out with it."

Yelena huffed. Well, if she was already here... "We were sparring, and things got pretty heated. She told me the Avengers were the family she never had, that she didn't ask for me to come back... I guess I lost it, and I hit her for real."

Tony nodded slowly, trying to process all of the information. This didn't sound right. Yes, Natasha was stubborn, but never has he seen her blatantly insult her little sister like that. "So, you hit her. Is all that all you did in retaliation?"

"I..." Yelena absently ran her hands down her face, trying to remember what she had said. "I told her how while I was fighting for my life, she was partying in the Tower. I insulted you guys, her family... I guess it just hurt knowing that the Avengers took her away from me..."

"Hm." There it was. They were getting somewhere now. "You know about the so-called 'Civil War', right?"

The assassin scoffed. "Duh, that's what Natasha wouldn't shut up about when we reunited."

Tony tapped her fingers against the table, mentally kicking himself. Of course she knew about it. "Well, during that time, our team had a really messy breakup. Natasha was the only rational one out of all of us. She chose friendship and ended up paying dearly for it."

Yelena gulped and looked away. She hadn't known that.

"I don't think she meant to hurt you. I know Steve didn't mean to hurt us; he just chose a different path. Yes, the Avengers may be Natasha's family-" Tony placed a hand on Yelena's shoulder, causing her to look up. "- but there is no one she loves more than you. She only needs you to have an unstoppable team." He removed his hand from Yelena and crossed his arms, smiling broadly as he looked to the ceiling. "Why do you think we try and stop you guys from being on a team together during our game nights?"

Yelena laughed softly, her walls coming down as she loosened up in Tony's presence. Sometimes she still couldn't believe Tony Stark was her friend.

"Alrighty." Tony pushed off of the table and clapped his hands together. "So now we know you both were at fault here. You attacked each other's weak points as a good fighter should. But it's apology time. Who's going to go first?"

Yelena stood up a little taller, her anxiety growing inside her. Would Natasha even listen to her?

"She'll listen," Tony assured as if he read her mind. Yelena snapped to attention, but Tony waved her off. "Don't worry, kid, I'm not physic. I just know that look. Now run along and talk to her. And if she doesn't accept your apology, you can hang out here until she comes around." Tony picked up a pencil and tucked it behind his ear. "But she will. So don't worry about it."

Yelena nodded and smiled a little. "Thank you, Tony."

"No problem, mini Romanoff. Now go!" Tony ushered her out of his lab with a careful push to her shoulder. "This is the part of the movie where the two heroes reunite in a big, dramatic, heartfelt moment."

"Never took you for a romantic, Stark," Yelena teased over her shoulder as she made her way to the door.

Tony only grinned. He had done his duty as the mentor. It felt good.

xxx

Yelena climbed the stairs to the living quarters part of the compound, making her way to Natasha's room. She knew that searching for her was useless; the building was too big. But Natasha had to come back to her room at some point, so she decided to wait there instead.

It wasn't long before a disheveled Romanoff came opened the door, freezing as the pair made eye contact.

Yelena gulped. Here goes nothing. "Hey. Fancy seeing you here."

"In my room? You knew I had to come eventually."

"I did." Yelena hopped off Natasha's bed and slowly approached her, stopping a couple of yards away. "That Clint's handy work?" she asked, pointing to the bandage on Natasha's face.

"Yep." Natasha shifted uncomfortably on her feet. "Listen... I-"

"I'm sorry. You deserve this family."

Natasha was taken aback. She did not expect Yelena to apologize first.

"I tried to make you feel guilty for being happy. It's not your fault." Yelena sighed and looked toward the wall. It was easier to talk to the blank surface than looking into Natasha's eyes. "You didn't know about the red room. You shouldn't feel bad about having a good life. Maybe I'm just... jealous."

"Yelena..."

"Please, just." Yelena held her hand up and smiled a painful grin. "Let me finish."

Natasha gave a curt nod.

"You're... everything to me, sestra. You're all I have. So..." Yelena picked at the palm of her hand, still actively avoiding confrontation. "Hearing you talk about the Avengers like they're the only family you have... eto bol'no..."

Natasha's heart broke as Yelena choked out the last bit in Russian. She had done this to her in a childish act of rage. Some sister she was.

"I don't think you're selfish... If anything, I am. I want you around all the time, and that's not fair to you, so..." Yelena hunched her shoulders and squeezed her hands into fists. "I'm sorry. Please don't hate me..."

"Rooskaya..." Natasha boldly stepped forward, lessening the gap between them. "You are my family. You were real to me, and all I ever wanted to do was protect you, but clearly, I failed at that." The Widow looked down at her fingers, flexing them slightly. "I wanted to forget. The pain was too much, so I made myself forget. I'm so sorry."

Yelena walked closer as well, close enough so that she could carefully touch the side of Natasha's jaw.

Natasha bumped against Yelena's palm, proving that she trusted her.

"Ya ne mogu poteryat' tebya," Yelena whispered under her breath, her thumb brushing over the bandage as her eyes shone with fresh tears begging to fall.

Natasha leaned in to press their foreheads together, her lip quivering despite her effort to stop it. "Ya tebya nikogda ne ostavlyu. Nikogda bol'she."

Yelena let out a watery laugh and moved to kiss Natasha's jaw before she wrapped her in a tight hug.

Natasha tucked her head against Yelena's shoulder, whispering hushed apologies into her t-shirt.

The Russian leaned into the Avenger's hair and sighed. "We both screwed up. Let's just agree to take a break from sparring for a while, okay?"

Natasha nodded, her grip on Yelena tightening. "That's probably a good idea." She lifted her head slightly and pressed a small kiss behind Yelena's ear. "I love you. And I promise this is real to me. You're my little sister. Mine."

A few tears escaped as Yelena nuzzled further against her big sister. "I love you too. More than anything."

xxx

Eto bol'no - It hurts

ya ne mogu poteryat' tebya - I can't lose you

Ya tebya nikogda ne ostavlyu. Nikogda bol'she - I will never leave you. Never again