I love writing about these two, and I have a lot of ideas swimming around in my head, but it's mostly just jumbled words. So if you have any requests, let me know! I'd like to write more about what you guys like. Russian translations are below.

xxx

"Natasha!" Yelena called out, leaning into the doorway to Natasha's room with her arms crossed. "I think we have rats; all of our food keeps disappearing."

Natasha groaned from her bed, rolling over onto her side. "We only have one rat, and it's named Yelena..."

Yelena scoffed dramatically, holding her head up high. "That is so rude; I think you should apologize for that." Her only response was a grunt. Yelena's arms dropped to her side and her eyebrows raised in concern. "Hey, are you okay?"

"Mmm..." The Avenger sniffed and carefully sat up in the bed, lightly slapping her face to wake herself up. "I'm fine, 'lena, just tired."

"Uh-huh." Her sister gave her a quick once over and shook her head. "I'm not believing that for a second. You look like trash."

"Gee, thanks," Natasha mumbled under her breath as she pushed off the bed and onto her feet. The reformed assassin attempted to walk past her sibling but her attempt was quickly foiled by Yelena simply stepping a foot to her right.

"Nice try, sestra," She gently prodded, reaching out to grip her shoulder.

Natasha huffed and stared her down, seeing if maybe an intimidation technique would work better.

Yelena squinted at her suspiciously. "What are you doing? Stop that; you look ridiculous."

With a drawn-out sigh, Natasha backed down. "Please just let me go; I'm fine," she practically begged, haphazardly pushing at Yelena's arm.

Yelena slipped the hand on the Avenger's shoulder up to the side of her neck, grazing the skin with her thumb. "You're warm."

Natasha tried her best to not lean into her touch. "I was under a lot of blankets, okay? Now, if you'll excuse me-" She jerked away and pushed past the blonde, making her way toward the kitchen. Natasha hadn't realized until now her legs felt like jelly, and before she could think about it, her body gave out on her. She tensed, expecting to hit the floor, but a strong arm caught her before the inevitable happened.

Yelena tugged Natasha against her body, holding her from behind. "You have fallen," she whispered into her ear, referencing the movie they had watched together a few weeks prior.

That resulted in a frustrated eye roll. "You have a serious Disney addiction."

"Maybe, but let's be real here." Yelena held Natasha with both arms and rested her chin on her shoulder. "You could probably use a big marshmallow doctor right now, and I'm the closest thing you've got to that."

Yelena's heartbeat pounded against Natasha's back. She must've really scared her when she fell. Natasha felt bad for trying to deny the obvious, so finally, she caved. "I would prefer the marshmallow, but I guess you'll do." Yelena's wonderful laugh filled Natasha's ears, making her smile.

"Well, I can put on puffy clothes if you'd like, but for now, will you be able to stand on your own?"

Natasha knew Yelena was just being protective, but that didn't make the question any less humiliating. "Yeah, I should be okay."

"Alright." Yelena slowly let her go and walked around to her front. Her arms crossed over her chest as she observed the state her sister was in. Dark circles ran under Natasha's eyes; her nose red and irritated. Her hair was unkempt; her skin, moist with perspiration. Bottom line: she looked awful. "Now, turn around and go back to bed, Romanov, I mean it," the assassin ordered with a smirk, enjoying this way too much.

Natasha playfully flicked Yelena's nose, not wanting her to have too much power, then turned to walk back to her room.

"Hey!" Yelena protested, her jaw-dropping in shock. "That's assault!"

A pleased smile graced Nat's lips. Her body ached, and her head felt like she was underwater, but no force on earth would prevent her from being the annoying big sister.

The peeved blonde followed her into the room, watching her carefully in case she decided to try another nose dive. As soon as Natasha crawled into her bed, she switched back into serious mode. "Okay. What do you need? I can go get it for you."

Natasha smiled fondly and leaned back against the headboard. "Oh, you were being serious?"

"Yes!" Yelena practically bounded over to Natasha and sat on the edge of the bed. "Nat, you always look out for me. And I've never..." Yelena breathed out through her nose slowly, debating how much she wanted to admit. Telling people how she felt was not her strong suit. Eventually, she looked at her sister and matched the Avenger's soft expression. "I want to take care of you. If you'd let me at least try?"

Natasha reached out for Yelena's hand, which the Russian quickly took and ran her thumb over Natasha's knuckles. "You're so sweet," the older woman whispered, her eyes cloudy with congestion. But her love still shined through.

Yelena scoffed and let go of her hand, shaking her head. "You've gone soft, bol'shaya sestra," she teased quietly, the beginnings of a smile forming on her face.

A cough mixed with a laugh bubbled in Natasha's throat, forcing her to sit up and deal with a coughing fit.

Yelena quickly leaped up to soothe her, rubbing her back and shoulders with care as she kept a close eye on her. She hoped this was the correct thing to do because she had no idea how to care for another human.

"Who's soft now?" Natasha hoarsely challenged after one final cough, looking up at her little sister with a triumphant grin.

The Russian let out a frustrated hum. She hated it when Natasha proved herself right. Which happened all the time. "Zamolchi..."

Natasha snorted. "Hey, um..." Her shoulders dropped sheepishly as she prepared to ask for help. Asking for help was not her strong suit. "Can I have some water...?"

"Get it yourself," Yelena deadpanned as she was already walking out of the room. It was easier to pretend she didn't want to do this instead of openly expressing how much she would actually do for her. Which, in short, was anything. She returned a few moments later, holding a glass of water and several small white bottles.

Natasha eyed them curiously. "Where'd you find those?"

"Under the sink. They say they're for colds, so I brought them all," Yelena coolly explained as she set the bottles down and handed Natasha the water.

The Avenger took a careful sip as her sister reclaimed her seat on the bed. "You're not supposed to mix medications like that, you know."

"I know. I just wasn't sure which was the best, so I figured I'd let you choose. You know, so that if it's not the right one, it'll be your fault, not mine," the assassin reasoned, her tone full of playful energy to keep Natasha's spirits up.

Natasha huffed and picked up a random bottle, inspecting it. "This is so dumb," she muttered under her breath as she removed the cap from the container. When she looked back up, Yelena had a hurt expression on her face. Natasha's eyes widened in realization. "Oh, hey, I didn't mean that what you were doing was..." The redhead struggled to find words, her mind swimming. All she wanted was to make sure her little sister felt needed. "I meant that I'm trained to do some pretty insane things, and yet a head cold is what takes me down." Natasha laughed humorlessly. "Crazy, huh?"

Yelena swallowed hard and nodded.

She hated how easily she would let herself get hurt by Natasha's words. They still had a lot of work to do, a lot of damage to fix, and that was okay. But Yelena still yearned for Natasha's approval. She wanted to find favor in her sister's eyes.

"Shall I provide you with an Ibuprofen to add salt to the wound?" Yelena eventually settled on, smiling a crooked grin. Hide the pain and discomfort with humor. It was easier this way.

Natasha blew air out her mouth but gave no verbal response. She placed a small pill on her tongue and washed it down with some water. Grimacing, she carefully laid down in the bed with a definite groan.

Yelena chuckled and rested her hand on Natasha's calf, squeezing it gently. "Anything else you want me to do for you?"

"You can get over here, for starters," the Avenger practically demanded, tapping the spot next to her. "You're warm. And I feel like crap."

"So needy," Yelena complained, hopping over Natasha's legs to lie on her other side.

"Don't care." Natasha pushed her head under her sister's chin and shivered. "You wanted to help. And this is all I want from you."

Yelena smiled softly and rested her head on top of Natasha's. "Just wait until the cool kids hear about this. Their favorite girl boss assassin, brought down by a cold. Sad."

Her sister rolled her eyes and pressed harder into the crook of Yelena's neck. "If you tell them this is a reminder that I know where you sleep at night."

The Russian laughed and pressed a fond kiss to Natasha's hairline. "And this is your reminder that only one of us was named the best child assassin." It was then when she noticed just how warm Natasha really was. Natasha's soft pants against her neck alone were enough to raise the alarm bells in her head, but the rest of her body felt as if she had been stuck in an oven for a while. It was concerning, and Yelena didn't know what to do. "Nat? Are you sure this is what you want? You seem like you're way too hot..."

"I'm fine," the widow mumbled for what felt like the millionth time that day. It was a reflex.

"No, you are not!" Yelena jerked away and pinned Natasha to the bed swiftly so she would pay attention. "Stop being an идиот and listen to me! You're not made of marble, so stop acting like you're invincible! Let. Me. Help. You."

Natasha could only stare up at her, noticing how hard she was breathing. She was really worked up about this. About... her.

Yelena breathed out slowly, still looking down at her, then let her go and got off the bed. "Get changed into cooler clothes. I'm going to try and find an ice pack. Don't fall over again," she instructed firmly, giving her a look before she left. Natasha was stubborn, but Yelena had her beat.

Natasha slowly eased up on her elbows, warily eyeing the door. She was not about to test the younger widow's patience. With less than graceful precision, Natasha rolled off her bed and softly padded over to her dresser. She opened a few drawers and pulled out shorts and a light-colored tank top. The door opened behind her as she was carefully slipping the new, clean shirt over her head.

"You good?" Yelena asked, observing her sister's sagging posture.

Natasha slightly looked over her shoulder but didn't have to energy to engage in conversation.

Yelena shifted uncomfortably on her feet and began walking towards her, tossing the ice pack and the towel she was holding on the bed in the process. "Hey."

Arms slid across Natasha's waist, and she was tugged backward, almost stepping on Yelena's foot while trying to keep her balance. A small grunt of protest passed through the Avenger's lips.

Yelena pressed her nose into the back of her sister's shoulder and just breathed for a moment. Natasha's body temperature already felt more manageable. "Ty mozhesh' vernut'sya v postel'?" she quietly asked against her skin, using their mother tongue to make the question less pointed and more personal.

Natasha shivered and rested more of her weight against the assassin. "Ya tak dumayu...," she responded, patting the top of Yelena's hand in reassurance.

"I'm trusting you..." Yelena pressed a gentle kiss to her sister's shoulder and moved to stand the pair up straighter. She tapped her finger against Natasha's stomach as a warning before she dropped her arms away and let Natasha walk on her own.

The redhead huffed once and slowly made her way back to the bed, practically flopping onto it when she reached the end.

Yelena chuckled and shook her head. "You're so graceful, Sestra."

"Ugh..."

"Hm." The blonde strolled over and crossed her arms at Natasha's bedside. "You landed on the ice pack. You should probably move over."

With a valiant effort, Natasha rolled over onto her back, giving Yelena a 'are you kidding me?' sort of look.

"What? There's no point of me grabbing it if you were just going to overlook it." Yelena picked up the object and sat down next to her. "C'mere."

Natasha dragged her body over and rested her head in Yelena's lap, face up toward her.

Yelena's expression softened. "Who knew you were so touchy-feely when you're sick?"

The Russian slowly raised her finger to her lips and hushed her, grinning a moment after.

"Your meds must be making you loopy." Yelena smiled back at her, her heart filling with a fondness for the Avenger. She felt special seeing her sibling like this. So... affectionate. Yelena was younger, and therefore usually was the one being looked after, but right now, she would do anything to make her older sister feel better. "I love you, you know."

"I know." Natasha adjusted on Yelena's leg and pressed her head against her sister's stomach. "I'm pretty great."

Yelena scoffed and gently ran the ice pack along Natasha's hairline. "And a poser."

"Do you have any other insults in your arsenal?"

"Why should I; it's my best one!"

A calm silence fell over them after that. Yelena, with all the care she could muster, kept Natasha cool with the ice and occasionally stroked her hair. Natasha's eyes were closed, and Yelena figured she was asleep until she heard Nat faintly whisper her name. She paused and glanced down. "What's up?"

Natasha slowly opened her eyes, a glimmer of mischief shining in her eyes. "I am satisfied with my care."

Yelena instantly swallowed hard and jerked her head away. Despite their current position, she felt more vulnerable than ever. "пошел ты... You know part always makes me cry..."

Natasha chuckled and snuggled back into Yelena's side. "But I mean it. Thank you..."

The young assassin almost didn't know what to do with her sister's genuine compliment. She still wasn't used to being praised or thanked in this kind of way. This wasn't because she made an efficient kill. It was for looking after someone. It was for something good. Yelena bit her lip and brushed some hair out of Natasha's face. "You're welcome." Maybe this is how it begins. Maybe this proved she could be good.

xxx

Zamolchi - shut up

идиот - Idiot

ty mozhesh' vernut'sya v postel'? - Can you get back to the bed?

Ya tak dumayu - I think so

пошел ты - Screw you

xxx

Oh, and if you don't know, Big Hero 6 is the movie referenced a few times in this :)