Natasha saw the news of Iron Man, Doctor Strange, Wong, and Spider-Man fighting Cull Obsidian and Ebony Maw. She knew this was the right thing to do, although the thought of her getting hurt was more painful than get shot or stabbed by any kind of weapon. She pulled her phone out, and called. "Natasha? Are you okay? I saw the news!"
"Yes, Yelena. I'm okay. But...I need your help."
"Say no more." About a day and a half later, she was there. She was wearing a white tank top and black sweatpants. Natasha was in the middle of discussing with Steve, Sam, and Bruce. After the three guys left, she did their secret whistle. Natasha did it back. They joyfully embraced, with Natasha even lifting Yelena off of the ground. Then, Nat called everyone in. She introduced them, and Yelena jokingly said, "Oh, so these are Bird Boy, Captain America, and the nerd!" Sam rolled his eyes "Bird Boy? Really?"
"Yes. Now, I want to train before we get attacked again. Do we have plastic weapons or anything like that?" Sam replied that they didn't, to which Yelena then challenged him to a 1v1. He accepted. They started. She tried to punch him in the face, but faked it as she swept his leg and pinned him. He challenged her to a rematch, saying that he wasn't ready. She sent a few punches which he easily blocked, but then kicked him in the solar plexus, greatly affecting him. He threw a left hook at her, which she blocked with her arm, greatly hurting it in the process. He punched her arm again, then kicked her in the ribs, knocking her down. She then did the kip up, and punched him in the nose with too much speed to have him block. He nearly fell over, and was ready to keep fighting. However, Natasha ended the fight when she saw the blood pouring out of his nose. She said that the sorry ass bird boy got his ass kicked by her baby sister. He said that he was going easy on her. Yelena came at him, and he flinched. She asked Rogers if this was really the elite team she was looking at. "Do you wanna fight me now?" he jokingly asked. She turned to Natasha, who was shaking her head. "He's a super soldier. Like our daddy!"
"Daddy? I thought you never knew your father, Natasha..."
"I didn't know my biological one. The Red Guardian, Alexei Shostakov, raised me and Yelena for a few years before we were taken into the Red Room. Yelena was such a little badass."
"I did have a good big sister taking care of me." Rogers was surprised. They were in the middle of a war with extraterrestrial beings now, but he'd never seen Natasha smile so much. Bruce said, "Guys, I'm sorry to interrupt, but...the guys attacking at New York, they're now arriving to Scotland for the Mind Stone. They're coming for Vision." Rogers responded, "Suit up everyone. To Scotland we go." Yelena followed Natasha to her room. They were sisters, so they could change in the same room. They both had their shirts off, and Natasha shook her head, admiring her little sister's figure. "I wish I had abs like that." Yelena proudly smiled. Then she noticed something. She pointed to her lower left abdomen. "How did that happen?" Natasha sighed. "The Winter Soldier tried to kill a scientist. I protected him, standing in front. He fired through my torso, and killed him anyway. This is why I don't show much skin anymore..."
"The Winter Soldier? The ghost assassin? The one that's actually Cap's best friend?"
"Yeah"
"I wish I could meet him. But for now, we have a mission." They finished changing, and went to the Quinjet where they eventually arrived at Scotland. Bruce said that he'd stay back, and let them know that they have a tracker on Vision. Yelena said it won't be necessary, pointing to a laser in the sky. "Let's kick some alien ass." Yelena, Natasha, and Rogers all dashed towards it, as Falcon flew. They saw Vision, injured, struggling to fight Corvus Glaive, and Wanda struggling against Proxima Midnight. Midnight threw her spear at Rogers, who easily caught it. Falcon flew up in the sky, and kicked Proxima Midnight through a window into an abandoned cafe. Yelena and Cap both assaulted Corvus, before Yelena used a Widow's bite on Midnight. Yelena stood near Glaive, as Natasha disarmed him of his glaive, and Yelena caught it. Simultaneously, Natasha stabbed Corvus in the stomach, and Yelena stabbed Midnight in the heart, and removed the blade. Midnight was dead. "We don't want to kill you but we will." Glaive was wounded on the ground. Vision used his very little remaining power to blast through Corvus's head, killing him. While they didn't know it, Ebony Maw was also dead. Now 3/4 of the Black Order was dead. Yelena laughed at Glaive's corpse, and noticed three holes in his stomach from how Romanoff stabbed him. Natasha sadly knelt down, knowing that they just ended two lived. Yelena went down to her level, and put her forehead with hers. "большая сестра(Big sister), it's okay. You know what Banner said. If Thanos succeeds, half of us die." She kissed her hair, and embraced her. They got up together. Falcon joked, "I never thought Natasha's sister would be so...soft with her." Yelena glared at him and threatened, "Do you need a third beating?"
"No, sorry. I won't say anything." She smiled "Good. So, Captain, what's next?" He smirked. "Wakanda." They traveled to Wakanda in their Quinjet. They arrived in Wakanda, met up with T'Challa and the other Wakandans. Shuri and Yelena formed a younger sibling bond immediately. T'Challa said, "You'll have my King's Guard, the Border Tribe, the Dora Milaje, and..."
"A semi-stable 100 year old man." Bucky Barned approached the group, and he embraced with Steve. Yelena stepped forward. "Is this him?"
"Yeah." She bitch-slapped him. "That's for shooting Natasha." He smiled, and said that he liked this kid. They realized that the fight was coming. Shuri began operating on Vision. She had a few guards and Wanda stay with her just in case. Hours later, the battle of Wakanda started. With Yelena around, and Corvus and Proxima dead, the battle was significantly not as hard. However, they were still outnumbered. Until Thor, Rocket, and Groot arrived, effortlessly destroying most of the army. Banner fought Cull Obsidian in the Hulkbuster armor. He was assisted by War Machine and Groot, and eventually killed him. Then...Thanos arrived. He effortlessly defeated everyone. Yelena was gonna approach him, but then saw Thor, and had a plan. Instead, she spent her time freeing Natasha from the prison Thanos had trapped her in. Thanos needed the mind stone. But Vision and Thor arrived in time for him. Vision distracted him for a bit, until Thanos overwhelmed him, and defeated him. It was then. Natasha and Yelena used half of their Widow bites that they had on Thanos, paralyzing him. Then, Thor arrived in the nick of time, throwing the axe at Thanos' chest. "I told you, you'd die for that." He dug it in deeper, thinking he'd killed him. Thanos then taunted, "You...should've gone for the head." Immediately after he said that, Vision severed his left arm off with the mind stone, removing the gauntlet from his possession. "And you should've waited till you got all six stones." Thor removed the axe from his chest, but saw the terrifying look of murderous intent in his eyes. He still had a long fight ahead of him. Or not. The two Widow's used the rest of the Widow's bites, once again paralyzing the Mad Titan. Thor then took a mighty swing, and beheaded Thanos. They looked around, and couldn't believe it. They had won! First thing was first though, they removed the stones. Then, Rogers used the space stone to teleport the Guardians, Iron Man, Spider-Man, and Doctor Strange over to where they were. They were all joyful about their victory, except Quill, who was still devastated about Gamora's death. Tony, who had been operated on and healed by Nebula said, "So...how about some fancy restaurant? Food's on me!" They all together went to the Quinjet, and had victory dinner at a fancy restaurant in New York. Shawarma's wouldn't work anymore. They talked about their battles, Natasha mentioned how she and Yelena killed Midnight and Glaive, Banner boasted about killing Obsidian, and Tony proudly told them about how Peter gave him the idea of how to kill Maw, saving Strange's sorry ass. They asked what they'd do next. Thor said that he'd lost his brother, parents, best friend, three close friends, and many of his people, so now he'd just go somewhere on Earth and try to find a new home for the Asgardians. Bucky said he'd live with Steve, and Steve joyfully accepted. Everyone went home. The Guardians, however, would just go off to space and have more adventures. Natasha had been in hiding for two years, so she and Yelena decided to move over back to Ohio, and just live their lives together in a house, so they could simply be sisters in a home again. No one could believe it, but for what truly felt like the first time ever, they had finally achieved peace. There would be more trouble in the world. There would be more terrorism, aliens, injustice, and crimes out there. But for now, they finally got their rest. At the end of the night, everyone left the restaurant and went home.