Summary: Some of the rules SHIELD has have funny origin stories, but you'll be hard pressed to find out what they are. It's a good thing SHIELD is the best spy agency in the world and can hide almost anything. Sometimes, though, it's good to recount how some rules came about.

Or the 5 times Steve and Natasha are the reason a new rule is made at SHIELD and the one time it's Nick Fury's fault.

A/N: The +1 at the end has a minor Captain Marvel spoiler.

1. SHIELD Recruit Rule #267: The bringing of live pets into SHIELD headquarters is prohibited no matter how "very friendly" or "not yours" they are.

Steve was pretty sure Natasha was insane. They'd barely survived the blast of the building they'd just flattened and Natasha was worried about a small garter snake she'd almost stepped on in her haste to escape. She'd picked it up without hesitation and carried it to safety with her away from the explosion. It was wrapped tightly around her fingers and was only about 30 centimetres long. Unlike them, the snake was completely uninjured.

"We can't leave it here," Natasha protested, holding the snake close to her body, but far enough away from where Steve was wrapping a burn on her arm that it wasn't in the way.

"Nat, it's a snake," Steve said, tying off the bandage and sitting back on his heels. "It can survive in the wild."

"It's a baby!" she exclaimed, thrusting the small snake towards Steve as if that would prove her point. Steve recoiled and glared at her. He'd already made it clear he wasn't a fan of snakes and she knew it. "I'll take him to the shelter to find a good home. He can't stay here with a burning building nearby; it's too dangerous."

"Fine," Steve agreed. "But you absolutely cannot let it loose in the quinjet on the way back."

"Deal," Natasha replied. She turned away from Steve and got the quinjet ready to take off. Once it was in the air, she plugged in SHIELD headquarters's coordinates and set the jet to autopilot. She lifted her hand with the snake so she could look at the small creature closer and smiled. "Don't worry," she told it. "You'll have a good home when we get back to New York."

* * *

They were halfway through their debrief with Fury before anything went wrong. Natasha had tucked the snake in the pocket of her SHIELD sweatshirt so she didn't have to worry about Fury seeing her holding it. With the warmth from her body, it had quickly fallen asleep and she didn't worry about it. At least, she didn't until she noticed Steve tense up and shy away from her slightly. Fury gave Steve a strange look but continued talking. When he looked away, Steve motioned frantically towards Natasha's lap where the snake had crawled.

"...I assume?" Fury asked, looking at Natasha pointedly. She barely heard him in her haste to stuff the snake (gently) back into her pocket.

"Of course," Natasha answered automatically. It wasn't until a few seconds later when she realised what she'd just said. "I mean no."

"What is it? Yes or no?" Fury asked. Natasha felt the snake leave her pocket again and fought the urge to look down at it.

"No," she replied firmly. Fury nodded skeptically then turned to Steve. Natasha reached around her lap for the snake, trying not to draw attention to herself, but couldn't find it. When she looked down at her lap, the snake was nowhere to be seen. She cursed quietly, but both Steve and Fury noticed.

"Something the matter, Agent Romanoff?" Fury asked.

"No," she replied smoothly. Fury didn't look convinced in the slightest, but she didn't have time to worry about that. She could see the snake slithering across his office towards the door. "You know what, I'm going to go to the bathroom," she announced. She didn't wait for permission as she hastily got up and followed the snake through the door. Unfortunately, the carpeting allowed the snake to blend in and it took her a second to spot it on the ground. She lunged forward, but it skittered out of her reach and further down the hall. Growling in annoyance, she got off the ground and followed it. Natasha lunged for the snake again, barely managing to grab it before it could disappear.

"Natasha?" Maria asked from behind her. Natasha stuffed the snake in her pocket, keeping her hand around it so it couldn't escape again, then got off the ground to face Maria.

"Hey," she replied. Maria raised an eyebrow at her suspiciously.

"What's in your pocket?" she asked, glancing down towards the sweatshirt pocket. Natasha followed her gaze then shrugged.

"Nothing," she said. She smiled at Maria as she walked past and back into Fury's office. As she sat down, Fury handed her a file of paperwork to fill out. She frowned but grabbed it, forgetting she was holding a snake and accidentally letting it fall on the table. Fury recoiled so fast Natasha was worried she'd dropped a grenade instead.

"Where the hell did that thing come from?" Fury demanded. Natasha snatched up the snake, cursing it for not staying in her pocket. "SHIELD isn't a pet friendly workplace."

"Ah come on, Nick," Natasha said. "He's really friendly and he's not even mine."

"How do you have a snake that isn't yours?" Fury asked, crossing his arms.

"She found it on the field," Steve answered. Natasha turned and glared at him, but Steve didn't seem too distraught about betraying a snake. "She's setting it free as soon as we're done here," he said, looking at Natasha pointedly.

"Set it free right now," Fury demanded, pointing towards his door. "And if you bring another animal back from a mission that isn't a cat, you're fired."

"You're such a bore," Natasha groaned, walking out of his office and making her way towards the SHIELD gardens to release the snake. Who knew Fury was so against snakes?

2. SHIELD Recruit Rule #268: Under no circumstance are you to play hide and seek in the dark on any floor level.

In all honesty, it was Clint's idea. He'd been the one that suggested they use the entire 41st floor to play an intense game of hide and seek in the dark after a particularly rough mission. He had stitches in his forehead, Natasha had dislocated her knee, and Steve had a broken wrist, but Clint wasn't going to be put off by "minor injuries". Steve and Natasha had agreed on account that Clint was the seeker. He'd agreed immediately and the game had started an hour ago.

"Shh," Natasha hissed, covering Steve's mouth as he chuckled quietly. They'd just moved spots after a close call and Natasha was not about to lose now.

"Sorry," Steve whispered. They heard the door open and simultaneously stopped breathing. Natasha tucked further behind the bookshelf and Steve crouched beneath her. The footsteps came closer and Natasha looked down at Steve. She made a claw with her hands and mimed yelling, telling him to jump Clint as he passed. Steve grinned and nodded, trying to stand up slowly without making a sound.

Even though there wasn't much light, Natasha could see the figure of a person in the window opposite them. As soon as they were in front of the bookshelf, Steve lunged out, Natasha hot on his heels, and yelled. Natasha jumped on Clint's back, surprised when he seemed taller than she was used to, and yelled in his ear.

"What the f—" the person threw Natasha from his back and she landed on her back on the other side of the room. She groaned and glanced up at Clint, about to yell at him for throwing her so hard, but froze. That wasn't Clint.

"Oh god," Steve said, covering his mouth as the lights flicked on and he was met with the sight of a very angry looking Director Fury.

"What the hell is going on?" he demanded. Steve looked at Natasha who was slowly picking herself up from the ground, rubbing her wrist in pain.

"We thought you were Agent Barton, sir," Steve replied. Fury did not look impressed. "We were playing hide and seek."

"And I suppose you thought it'd be fun to jump on him and scream like five year olds, am I right?" Fury asked, glancing at Natasha. "You deserve that," he told her, pointing towards the wrist she was holding tenderly. Steve frowned and walked over to where she was glaring at Fury.

"Yes, but clearly that didn't work out," she replied. She let Steve examine her wrist, gritting her teeth when he moved it and pain shot up her arm. It was definitely broken and would need to be examined by medical before they continued their game.

"Well next time, think about who else could be walking through the room," Fury told them. He walked over to a desk, grabbed a file, then left the room, mumbling about running a circus instead of a top spy agency.

3. SHIELD Recruit Rule #269: The deck of the helicarrier is not to be used as a roller rink.

"It'll be fun," was the last thing Steve remembered Natasha saying before he agreed to her idea. He wasn't even sure where she'd found roller skates in his size, but he wasn't going to ask. She herself was wearing a pair of black roller blades, waiting impatiently for Steve to put on his skates.

"Are you sure this is allowed?" Steve asked, following her stealthily towards the exit on his skates.

"It isn't not allowed," she replied. She punched in a code and the exit door slid open. The wind from outside blew her backward and into Steve, but she pushed herself out of the door and onto the deck of the helicarrier. Once Steve was out, the exit door shut and latched, leaving them to the mercy of the wind and sky. With the ground thousands of metres below them, if they fell off the edge, they were probably screwed. Steve was just glad he'd managed to convince Natasha to wear a parachute just in case.

"So what's the plan?" Steve yelled over the wind. It blew him slightly, but he wasn't too worried. Natasha, in the meantime, was spinning in circles and letting the wind push her wherever.

"Don't fall off the edge," Natasha answered back, yelling as well. "See how long we can stay out before someone drags us back in."

"Got it," Steve replied. Natasha stopped her spinning and nearly toppled over. She stabilised herself then looked at Steve with a grin.

"Race ya," she said. Before Steve could ask what she meant, she took off across the runway of the helicarrier, using the wind at her back as an advantage. Steve rolled his eyes then shot after her, gaining on her slowly. She glanced back and then propelled herself forward even faster. They were three-quarters of the way across the deck when Fury's voice came over the outside intercoms.

"Agent Romanoff and Captain Rogers," he greeted. Natasha stopped short and Steve crashed into her. They didn't fall, but they slipped and slid for a few seconds before regaining balance. "Just what do you think you're doing?" They both knew it was a rhetorical question since he didn't have any way of hearing their answer and they doubted he actually wanted to hear it. "Get back inside right now," he demanded. Steve sighed and glanced at Natasha, about to ask her where the nearest entrance was when she took off.

"Nat!" Steve yelled, racing after her. She was skating quickly towards the edge of the deck and didn't appear to be slowing down. When she grabbed hold of her parachute pack, Steve knew what she was going to do.

"Romanoff, I'm warning you," Fury said over the intercoms. She didn't care. Natasha threw herself off the deck of the helicarrier and nose dived towards the ground. Steve followed after her, glancing over at her to see her grinning widely.

"Good thing we have the parachutes," Steve yelled. Natasha looked at him and nodded.

"Who'd have thought skating on the helicarrier deck would have resulted in plummetting towards the earth?" Natasha teased. Steve rolled his eyes and made himself smaller so he was falling faster. Natasha glared and copied him, able to stay just ahead of him as they plummeted. When they got closer to the ground, the self deploying parachutes they had were activated and their free fall was over. They hit land just outside of Miami, Florida and managed to find a taxi that could take them to a car rental so they could drive back to DC. Flying was over rated.

4. SHIELD Recruit Rule #270: Do not ask Agent Hill to accompany you to the mall today or any day.

Maria looked less than thrilled to be walking around the mall with Natasha. Natasha looked almost as miserable, but Steve was proudly leading them through the throngs of people towards what he claimed was the best chocolate place within walking distance of SHIELD headquarters. Walking distance had turned out to be nearly five kilometres and it'd taken them 45 mins to get to the mall. If the chocolate was anything less than extraordinary, Maria was going to have a fit.

"Here we are!" Steve announced, walking into a small shop. Natasha and Maria looked around the store but weren't immediately impressed. Steve rolled his eyes and grabbed a box of his favourites. He bought it then opened it in the store, offering some to the girls. They each grabbed a truffle and bit into it.

"Not exactly worth the forty-five minute walk, but they are pretty good," Maria replied. Steve beamed and Natasha stole another one of his chocolates, grinning cheekily when he frowned.

"I think the truffles are the best," Steve told them, grabbing a truffle from his box and stuffing it in his mouth. "But those bars are pretty great too," he said, pointing towards a shelf of various chocolate bar flavours. Natasha lit up at the sight up them and walked over to investigate.

"This is where you get all that chocolate?" she asked, looking through all the different flavours.

"Yeah," Steve replied, standing behind her. "If you find a flavour I don't get that you like, let me know."

"Oh I will," Natasha said. Steve smiled and glanced at Maria who was meticulously looking over some chocolate carvings. Once Natasha had grabbed enough chocolate to restock the supply Steve kept in his room for the two of them (post-mission chocolate was the best kind), they left the chocolate shop.

"Can we take a taxi back?" Maria asked.

"Does SHIELD allow taxis?" Steve replied, taking the bag of chocolate from Natasha as she pushed it into his hand.

"Not past the gate," Maria answered, stepping onto the escalator. "But it's better than walking all the way back."

"I thought you liked morning walks," Natasha teased. Maria rolled her eyes.

"11:30 AM isn't really morning and my walks aren't five kilometres long unlike super boyfriend over there," she said. Steve choked on air and started coughing at what Maria had implied, but Natasha seemed unfazed.

"Why don't you like the mall?" Natasha asked, ignoring Steve's coughing and leaning against the escalator rail.

"Too many people," Maria replied, stepping off and walking towards the next escalator. "It's easy to get caught off guard and when you pull a gun in public, people get upset."

"Fair point," Natasha agreed. Steve finally got his coughing under control as they stepped on the second escalator and rode down. "So you wouldn't like it if I said the guy in front of you just stole your watch."

"What?" Maria said, twisting around and grabbing the guy in a choke hold. He flailed around but Maria's grip didn't waver. "Give it back," she demanded. People nearby watched in horror as the man's face began to turn red then purple.

"I'm sorry," he choked, dropping her watch. Maria let him go and bent down to grab her watch. She stepped off the escalator calmly, as though she hadn't just manhandled a stranger in public. Natasha and Steve followed her out of the mall and let her hail a taxi.

"I don't think we should bring her next time," Natasha stage whispered to Steve. Maria turned back and gave them both an irritated look.

"Agreed," Steve whispered back.

5. SHIELD Recruit Rule #271: Do not title mission reports as though they are a Sherlock Holmes adventure. Especially if reading Sherlock Holmes was the reason the mission went poorly.

Perhaps their mission could have gone smoother than it had, but that would have required Clint to put down his book. While he wasn't usually a reader, he'd recently become a fan of Sherlock Holmes and had devoted himself to reading all the books in a week. Apparently, he wasn't willing to put his goal on hold because of a mission, so Natasha just left him on a building to keep an eye out for anyone entering the building. It was easy enough he could keep reading and just glance up every now and then. The alley was long and gave them plenty of time to notice someone walking down it, but Clint had been too distracted by his book to notice anything going wrong until a grenade went off beneath him.

After realising someone had gotten past him, he'd set his book down and dropped into the alley to help get Steve and Natasha out. It was one of the rare times the mission had required all three of them but only two had been actively working. Once they'd finally gotten away and were in the quinjet, they assessed injuries. Natasha had a nasty stab wound to her right shoulder that received immediate attention. She also had a broken wrist, a burn on her thigh, and a splattering of small cuts on her left arm. Steve had a concussion, a dislocated left shoulder, a large bruise on his hip, and a bullet graze on his left leg. Clint had gotten away mostly unharmed. Except for a cut on his hip and some scrapes on his hands from when he'd jumped from the roof, he was fine. That meant he got to be the one to fill out the mission report while Steve and Natasha went to medical.

"Agent Barton?" Fury asked, walking up to him in the medical ward. He was carrying the file Clint had dropped by his office and didn't look pleased.

"Yes, sir?" Clint replied, looking up from Natasha's bedside.

"I have a mission report here that is titled The Secret of E. Basilov," Fury told him, handing the file to Clint. "I don't suppose you happen to know anything about that."

"I don't see the problem, sir," Clint said, handing the file back. Fury raised an eyebrow then glanced at Natasha who was still unconscious.

"You don't see how a report that sounds like a Sherlock Holmes story is a problem?" Fury asked. Clint shrugged. "I have two of my best agents in the hospital while the third one is virtually unharmed. I know you would never compromise a mission by bringing along distractions, but I also know you've had a thing for Sherlock Holmes this past week and your book is on the quinjet. Do you see the problem now?" Clint didn't respond immediately. He waited until he was certain Fury wanted an answer and wouldn't leave until he got one before coming up with an excuse.

"To be fair, Natasha said it was okay," he said weakly. Fury glared at him instead of Natasha's unresponsive body.

"No more books on the field," he said before turning and leaving the room.

+ 1 (Minor Captain Marvel Spoiler)

SHIELD Recruit Rule #272: If you absolutely must bring a pet to work (and have a good reason), it has to be a normal household pet. Even if it appears to be normal, any pet that exhibits or possesses otherworldly abilities will be banned from premises and you will probably be fired.

Natasha had never really thought of Nick Fury as a cat person, but who was she to judge? She'd walked into his office after being told she had a mission to find Nick Fury gone and an orange cat sitting in his chair. Of course, after making sure no one else was watching or could see her, she walked over to the cat to pet it.

"Hello," she said, scratching behind its ears. The cat purred and pushed against her. She glanced down at its collar and read the name. "Goose? Fury named his cat Goose?"

"I wouldn't get too close," Steve said, walking into the room. Natasha glanced back at him then returned her attention to the cat. "I once saw that thing eat a HYDRA agent who'd managed to sneak into Fury's office."

"You don't have to bully it," Natasha said, running her hand over the cat's back. "You could just say you don't like cats."

"No, I don't mind cats," Steve protested, taking a seat far away from Goose. "That's just not a cat."

"And I'm not a spy," Natasha replied. Steve watched her skeptically, keeping an eye on both the cat and Natasha as they waited for Fury. Natasha had just put Goose in her lap when Fury walked in with a small case. He looked surprised to see Natasha holding Goose, but didn't say anything.

"I thought you didn't like pets," Fury said. Natasha shrugged and scratched Goose's head. "You might want to move."

"I'm not getting rid of Goose just because you want to spend quality time with your cat," Natasha replied. Fury shrugged and set the case in front of her on the table. He opened it to reveal what looked like an ancient, glowing tennis ball.

"Take the ball, leave the case," Fury said. Natasha raised an eyebrow at him skeptically and gingerly reached toward it. Before she got very far, though, what looked and smelled like a large octopus came out of Goose's mouth. Steve jumped back and Natasha stared in horror as long, red-pink tentacles shot towards the case, picked up the glowing tennis ball, then disappeared back inside Goose. Natasha stood up quickly, knocking Goose off her lap, and dove to the other side of the table. Goose just looked up at her then walked behind Fury's desk to lay down.

"What the hell was that?" she demanded.

"That was my cat," Fury replied calmly, taking the seat she'd hastily vacated. "He doubles as a flerken."

"A what?" Steve asked. Fury sighed.

"I don't know," he replied. He waved noncommittedly in Goose's direction. "Some space animal that looks like a cat but can eat at least six aliens at a time."

"Where and how did you find it?" Natasha asked.

"He found me," Fury replied. He slid a mission file across the table as if nothing had just happened. "Now, forget the flerken kitty and read your mission."