A/N: Hi guys! The long-awaited BuckyNat adventure... "thankfully" I got sick, and had the free time to finish writing it.

Russian Roulette

(takes place sometime before Infinity Wars)

"Bucky, Nat, you're up," Diana announced, walking into the training room where most of the Avengers were working out.

Nat rolled to a graceful standing position, and Bucky put down his weights. They both walked over. "Mission?" Natasha asked.

"Your mission, should you choose to accept it, is to go undercover in Poland and rescue a group of mutants. They were taken prisoner by scientists researching the X-gene. Your secondary priority is to sweep up all the data from the research, and if needed, destroy it."

"What about the scientists?"

"SHIELD will take them into custody if they can, but focus on the rescue."

Two terse nods. "When do we leave?"

Diana handed Natasha the tablet. "Whenever you're ready."

"Awesome."

Between the two spies, they had the information analyzed and their covers perfected by the end of the day. Natasha was now black-haired, with dark brown eyes, and Bucky was wearing a subtle face-mask to alter the shape of his nose and jaw.

"You know, this was a lot easier when no one on the planet knew what I looked like," Bucky griped, adjusting the mask so it wouldn't give him a butt-chin.

Natasha leaned over his shoulder to smirk at him in the mirror. "Poor, poor superhero," she sympathized. "You have to wear a disguise like everybody else." She patted his cheek with a patronizing air and turned away to finish the last touches on her makeup.

Bucky watched in awe as Natasha changed the look of her face with makeup. "Awesome," he said. "You look like a forty-year-old now."

She stuck her tongue out at him. "Keep it up, Barnes, we'll see if you don't look your real age by the time we get there."

"Whatever, Romanoff."

"Doctors Marko and Triesse" were on a quinjet bound for Poland.

They made landfall at night, and checked into a double bed suite in a cute little hotel on the edge of town. It was only ten minutes from the laboratory where the mutants were being held. There, they changed from slacks and button ups to dark casual clothes perfect for a little casual spying.

"High security," Bucky mentioned to Natasha, as they circled the block. "Cameras extending to the opposite side of the street. Smile."

She leaned up on her toes to kiss his cheek. "Normal high security, or our kind of high?"

He smirked and tugged at one of her jet-black braids. "Medium high, I'd say AIM-style. Biometric scans, wouldn't you say?"

"Probably. We'll need a scientist guide to get us inside."

"Yup." He directed her to the corner of the block, where a man was selling hot cups of tea. "Two please," he said, in flawless Polish.

He handed over two cups of strong, milky tea, and Natasha smiled her thanks as they walked away.

She took a sip. "Mm, clove. Definitely an outside guard."

"Yup."

"Is that all you're gonna say?" she demanded.

"Yup." He slurped at his tea.

"Pig."

"Yup."

She rolled her eyes at him. "You and Clint are spending too much time together."

"What? I had to see all the Fast and Furious movies."

She rolled her eyes again. "Shall we send an email, back-date it, and come back tomorrow?"

"We shall." He offered her his arm, and they strolled back to the inn, a picture of perfect contentment.

As soon as they got inside the room, Natasha sent an email to the lab, back-dated by three weeks, informing them of their visit from nearby Bio-Len labs. Inside the email was a virus that would insert an appointment into the calendar. "All right, we're good to go," she said.

Bucky nodded. "I'll take first watch."

"No, no, no, age before beauty," Natasha said, gesturing to the bed. "You need your rest, old man."

He rolled his eyes and flopped onto the bed. "Are you ever gonna stop making that joke?" he asked, kicking his shoes off.

"Nope." She perched on the edge of the sofa, facing the two exits.

"Is Steve still getting his anonymous AARP subscription?" Bucky asked, closing his eyes.

Natasha smirked. "Yup."

"Awesome. You know he actually uses it right? He gets senior discounts literally everywhere."

"I know. Why do you think I keep sending them to him?" She threw a pen at his arm, and it clanged. She smirked. "Why don't you get an AARP? You're the same age."

"I don't go out as much," Bucky grunted, throwing the pen back at her.

She dodged it. "You're boring, Barnes."

"Shut up, Tasha, I'm trying to sleep here."

She rolled her eyes.

At two in the morning, they traded. Bucky took watch, and Natasha curled up in his spot on the bed. "It's warm," she explained, to his curious gaze, pulling the covers up to her chin.

He just smiled.

The next morning, at 0800, Dr's Marko and Triesse presented themselves at the Polish lab. "We are here for our tour," Dr. Triesse said, her French accent fluid and enticing.

"Tour?" the startled assistant said, tapping at his computer frantically. "I don't think a tour is scheduled today-" His sentence broke off as he noticed hte little green square. "Oh," he said, clearing his throat. "I see that it is scheduled. One moment, please, while I call Dr. Marcus up here."

"Of course young man," Natasha replied, giving him a reassuring smile.

Dr. Marcus was a balding man who had evil intent shining from his eyes. He tried to cover it with a suave exterior, but both Avengers could sense it. Here was a ruthless man.

Bucky and Natasha exchanged a glance. They were not expecting the mutants to be in good condition when they found them, if someone like this was in charge of the experimentation.

They both paid half an ear to the tour, made the appropriate flattering comments, and scrupulously noticed everything Dr. Marcus didn't mention. It was a long list. There were also two unlabeled underground levels on the elevator...

After the tour, they gave their tanks to Dr. Marcus, and walked back to their inn. As soon as they got inside, Bucky turned on the dampening field in his suitcase. "When do we want to go in?" he asked.

"Tonight. We can't wait any longer."

They spent the rest of the day preparing their suits. Bucky and Natasha made a small contest of how many weapons they could fit in their suits. Bucky won by virtue of his arm being a plethora of weapons in itself.

The rest of the evening they spent resting and watching TV, cuddling on the bed. "You know, this is the most comfortable mission I've been on," Bucky decided, kissing her hair.

She poked him in the side. "Don't get too comfortable. In an hour and a half we have to rescue an unknown amount of mutants from an unknown underground compound."

"Suck the joy out of everything why dontcha," Bucky grumbled.

She rolled her eyes. "Buck, you are the personification of grumpy cat."

He smirked.

An hour and a half later they were sneaking back into the laboratory facility. With the biometric samples they'd collected earlier from the scientists, it was a piece of cake to fake the security scans and gain access. They bypassed the elevator altogether, and used the elevator shaft.

The underground levels reeked of antiseptic. "That's not a good smell," Bucky said grimly, ignoring the encroaching flashbacks to his past.

"No it is not," Natasha agreed. She touched his right arm. "You okay?"

"Fine." He heard a noise, and pointed. "That way."

They stalked down the hallway, and came to a row of holding cells. "Can you scan?" Natasha whispered.

"No, it's too heavily shielded." He gestured to the door. "Ladies first."

"Such a gentleman, Barnes," she grumbled, and picked the lock.

The door swung open, and they caught the smell of injury and fear. There were four people sitting on the floor, bruised and patched up, their beige scrubs dirty. "Who are you?" the oldest one asked, after a stunned moment.

Natasha gave him a small smile. "We're Avengers. We're here to get you out. Can you walk?"

They all nodded, and Bucky hauled them to their feet. Gently. "How many more are there?" he asked.

"Nine more," the older one said again. "Which heroes are you?"

"Black Widow, Winter Soldier," Natasha said.

"Oh. Cool."

The rest of the prisoners were in about the same shape, and the two spies herded their little group back to the elevator shaft. "Widow, go," Bucky ordered.

She went up to the top, and Bucky sent up the mutants. One of them was able to teleport herself right up to the top, and helped Natasha haul the other ones out.

"We have five minutes before the midnight walkthrough," Natasha reported.

"Uh-oh." Bucky grabbed the last mutant, a little girl, by the waist, and scrambled up the elevator shaft. "Let's go."

They put the cameras on a loop, and slipped out of the laboratory through the back doors. They were on the street within a minute. "Okay everybody, look casual," Bucky muttered, giving them a bracing grin.

Two yards away from the laboratory, all the mutants' arms began to flash.

"What in the heck," Bucky hissed.

Their rescuees all looked terrified. "They must have tagged us," one of them wailed. "We were unconscious a lot of the time."

Lights in the lab began to snap on, and alarms began to blare.

"Let's go," Natasha snapped, urging them all into a run. "Never mind stealth. Let's go!"

They hustled down to the inn, and Natasha activated the dampening field. Their arms stopped flashing. "okay, we have a minute before they trace the source of the dampening field," she said, and clicked on the computer. "Home base this is Operation Streetcar, calling for immediate extraction for eleven people."

It was Tony on the other side. "Operation Streetcar, this is Home base. A private plane is avaialable ten miles west of your position, in a private airfield."

"Copy that. Over and out." Natasha looked at the others. "Ten miles west. We need to get those things out of your arms."

They all winced.

"I know," she said, grimacing. "It's gonna hurt. Sorry."

"Do it," one of the mutants said.

The nine procedures were quick, bloody, and had everybody gritting their teeth in anxiety. But it was done in less than five minutes, while Bucky went to steal a car.

Shoving eleven people in a five-person car was like Twister gone horribly wrong, but they fit, and Bucky broke all the traffic laws between the inn and the airport. There was no one following them, but still. The Winter Soldier was well-known for his paranoia.

The little airplane was waiting for them, a SHIELD pilot at the helm. "Welcome aboard," she told the weary little band. "We're bound for England, by the way," she added. "Food and drinks, and first aid kits, in the cupboards."

"Thanks."

Natasha and Bucky made sure everyone was set up, and spent the three hours to England on alert. The mission wasn't over until the mutants were safely delivered.

Thankfully nothing happened, and the nine rescuees rested in one of SHIELD's med wards while they recovered. Diana vid-commed them to give them an update. The laboratory had "mysteriously" burned down in what looked like a gas leak, destroying all the information inside of it.

"Whoops," Bucky said innocently.

Diana rolled her eyes at them over the screen. "We'll see you when you get home," she said. "Good job."

"See you tomorrow, doll." Bucky turned off the tablet and looked at Natasha. "What do you say we go out for dinner?"

"You buying?"

"Of course. Whatdya take me for?"

Natasha smirked and kissed his cheek. "A gentleman."