On the first night that John moved in, he shot someone out of combat.

And he was kidnapped.

Weeks later, he literally fought ninjas while on a date.

Some time after that, he was kidnapped once again, only to be strapped to a bomb.

After the pool, John figured it was time he lay down some ground rules.

"We need rules," he announced, walking down the stairs two days after the pool incident.

"Rules?" Sherlock asks from his post on the sofa.

"Yes. Rules. We need," John waves his hands in the air. "I don't know. Roommate rules."

"What kind of rules?"

John walks over to the refrigerator and opens it. "I will tell you what kind of rules. Rule Number One," John points at the new head in the fridge. "Body parts in the refrigerator stay at a minimum."

Sherlock sits up and quirks an eyebrow. "Define minimum."

John looks back into the fridge. The only space being taken up at the moment is the head in the center rack. Other than that it's clear. "Two shelves must be free for food. And," he opens the drawers to check for fingers or toes or tongues or something. "One drawer free," he says, lifting a heavy bag of eyeballs out of the drawer.

Sherlock nods. "Fair enough," he says. "I can follow the one rule."

"No, no," John shakes his head, going back into the living room. "We need more rules than just one."

"Ok," Sherlock stands from the couch. "What else?"

"Well…" John looks around. "I can't think of any right now," he says.

Sherlock smiles. "Fine. I will keep body parts in the fridge to a minimum, then."

"That's all I ask," John says, heading for the door.

Sherlock turns around to watch him pull his jacket on. "And if I break any rules?" Sherlock asks.

John shrugs. "I don't know. I won't be happy about it."

Sherlock smirks as John reaches for the doorknob. "Will I be punished?" he flirts.

John glares at him. "Not in any way you may think, perverted git. I'll think of consequences."

Sherlock grins at John. "Looking forward to it," he says.

John shakes his head to clear it, then resumes out the door. "I'll be back with dinner," he announces.

When John leaves, Sherlock smiles at himself and goes back to the sofa. He loves to torment John like that.

John walks to get dinner and thinks about rules on the way. This could be good, he thinks. Someone needs to tell that man when he's wrong. As for consequences…'punishment' as he put it. Why must he do that to me? Play with my like that? John suddenly thinks of Rule Number Two. He gets his phone out to text Sherlock.

Rule Number Two: No making me uncomfortable. – JW

Seconds later, John gets a reply.

I don't know what you mean. –SH

John rolls his eyes and continues down the street.

Days later, Sherlock and John are at a crime scene involving very serious matters like cotton candy and unicorns. No really. John wrote the case up as "The Case of the Glittery Unicorn".

As Sherlock gives his deductions to Lestrade, it all strikes John as very funny. Not funny, funny, but, come on? Cotton candy? Unicorns? Suddenly he can't stop himself from giggling.

Sherlock glances at John and half smiles while talking to Lestrade, and within seconds of John's giggles, Sherlock begins on his deep chuckles.

"Gentlemen!" Lestrade snaps. "This is a murder scene. Have some respect."

John clears his throat and wipes tears out of his eyes. "You're right. I'm sorry."

Sherlock takes deep breaths and apologizes as well, then continues with Lestrade's questions. When he finishes, he and John walk back to the main road to get a cab.

"Rule Number Three," John says, giggling again. "No giggling at a crime scene."

Sherlock laughs. "You break that rule all the time."

"I do not!" John says. "The ruling stands. No giggling at a crime scene."

Sherlock grins. "Maybe I'll just have to punish you when you break that rule."

John's eyes grow wide. "Sherlock! Rule Number Two!"

Sherlock laughs. "Sorry, John."

"It's alright," John says. "You get a warning this time."

Sherlock grins again. "Maybe I—"

"Do not!" John snaps, making Sherlock laugh.

The next day, John wakes to the smell of smoke coming from the living room. He instantly jumps out of bed and rushes downstairs to see Sherlock putting out a small fire in their living room, just a few feet away from their chairs.

"Sherlock!" John shouts.

"Hello, John," Sherlock calmly says, spraying the fire extinguisher.

"What the hell are you doing!?"

"Minor explosion. Not a big deal. It's under control, see?" Sherlock stands back and sets the fire extinguisher down, then removes his safety goggles and takes a deep breath.

"New rule!" John shouts. "No experiments in the living room!"

"But, John—"

"Nope! You're lucky I'm not banning you from blowing anything up, young man. I don't want anything going on in the living room, especially around my chair. So more than no experiments in the living room, no experiments in the perimeter of my chair!"

Sherlock frowns. He hates when John calls him 'young man'. "Ok…" he says in defeat. "Define the perimeter around your chair."

John huffs and rolls his eyes. He stands next to his chair and draws an invisible circle around it. "Here. This is the perimeter."

Sherlock nods. "Fine. For the sake of your chair, I'll keep all experiments, especially the ones that explode, out of the perimeter of the living room."

"Good!" John says, turning around to stomp back upstairs. "We really need to write these down…" he mutters.

Sherlock takes John's advice and gets his laptop out to write down the rules, and to think of a few of his own.

Two days later, John goes on a date. Sherlock is not so happy about this because Sherlock wants John to help him with the case, but Sherlock does let him go.

"Wait," Sherlock calls after John. "I can make rules, too, right?"

"Yeah, sure," John says, stepping out the door. "I'm going to be late!"

Sherlock nods and watches John go, then gets his phone out to text John his new rule.

John finally reads it an hour later when he thinks to check his phone while waiting for a cab with his girlfriend.

Rule Number Five: No women. –SH

John scowls at the screen and angrily types back: That is absolutely not fair. –JW

He gets a reply seconds later. Fine. No women here. Unless you give me 24 hours notice. –SH

John takes a deep breath and types back. Fine. Sherlock, tomorrow I'm going to have my girlfriend over to spend the night. –JW

No. –SH is all John gets in reply.

John doesn't text back, instead he goes to her house for the night. When he returns home, Sherlock has a new rule tacked to the refrigerator. When I'm on a case, you come home each night to help me. –SH

John rolls his eyes and goes to his room.

They have six rules by the time they get taken to Buckingham Palace. When John sees Sherlock sitting on the sofa in nothing but a sheet, he wishes he'd mentioned a clothing rule, but he doesn't bring it up then. They have their meeting with Mycroft and in the cab, John mentions something.

"I should make a clothing rule," John says.

"Why?" Sherlock asks.

"You can't just go around to places completely nude."

The car stops and Sherlock gets out, completely ignoring John. John follows him up to their flat.

"Technically," John says, peeling his jacket off, "That did fall under Rule Number Two."

"Hmm?" Sherlock asks.

"You being nude in public. Rule Number Two."

"Refresh my memory."

John sighs. "It made me uncomfortable."

Sherlock looks up at John and stares at him curiously. "Did it?"

John nods.

"Well," Sherlock says, "I guess you'll just have to avert your eyes next time." Sherlock stands from the couch and pulls his jacket off, then begins unbuttoning his shirt while walking towards John.

"What are you doing?" John demands.

Sherlock walks right past him towards his own bedroom. "I've just got to get changed," Sherlock says in a playful tone.

John rolls his eyes and goes to his chair.

Later that day, they meet Irene Adler, and after that fiasco, John calls Lestrade for help. Lestrade meets them at Irene's home and helps John carry Sherlock to a car, but not before recording Sherlock stumble around and slur everywhere.

"John…" Sherlock mutters continuously as they get him into a car.

John slides into the car next to Sherlock, and Sherlock falls over and rests his head on John's lap. John brushes hair out of his face and rubs his skull, knowing it's probably comforting for Sherlock.

"Rule Number Seven," John whispers to Sherlock's sleeping form. "No naked women for you, young man," John leans down and kisses Sherlock's temple. "They're dangerous."

The day after Christmas, Sherlock mopes around the flat and tries his best to work and stay out of John's way. John is there, however, hovering over Sherlock every moment and asking if he's ok.

"I'm fine, John," Sherlock states.

"I'm just concerned, that's all."

"Why?"

"Because I know what it's like to lose someone you…" John trails off. He doesn't want to think of Sherlock as loving her or caring for her even, not when Sherlock won't say he cares for John just a little bit.

"She wasn't someone I anything, John," Sherlock says. "So stop asking how I feel."

John sighs. "Just let me know if you want to talk."

Sherlock doesn't say anything, so John heads for the door. As he's almost out, Sherlock says, "Rule Number Eight: Stop asking how I feel."

"But Sherlock, I—"

"Stop."

John nods and goes up the stairs to his room.

John goes home the afternoon he was kidnapped by Irene to see Sherlock working at the kitchen table. John stares at him a few minutes, then finally says, "Sherlock, are you—"

"Rule Number Eight, John."

John closes his eyes and gasps as if being punched. He nods and backs out the door once again.

A few weeks later, Rule Number Nine is added: No harpooning dead pigs and riding public transportation afterwards.

Then Henry Knight shows up and the go to Dartmoor. On the way, Rule Number Ten is added: Sherlock always drives.

After they check in to their rooms, Sherlock adds Rule Number Eleven: John must stop getting so angry when everyone assumes they're a couple.

"Now, hang on," John says after Sherlock informs him of Rule Number Eleven. "Doesn't that make you angry?"

"Why should it?"

"Well, because it's not true. And—"

"Frankly, John, I find it a bit insulting when you get so angry."

"Insulting? Why?"

"Because you feel so strongly about it. You don't have to get so angry. Trust me, I know you don't want to be with me. You don't have to find the idea appalling."

"You're the one that said—" John says, trying to bring up the fact that Sherlock denied John their first night together.

"Come on," Sherlock stops him. "We've got to go to the base."

After leaving the base, John adds Rule Number Twelve: No more stealing Mycroft's identification cards.

"That's no fun, John," Sherlock pleads.

"I don't want to go to prison."

When they go to Henry Knight's house, John is very amazed by the house. It's very obvious he's impressed by what Henry's got, so later that evening, Sherlock adds Rule Number Thirteen.

"No being overly impressed by what other people have," Sherlock says.

"Define 'overly impressed'."

"Don't act like Henry is the first person you've ever met with money."

John defends himself. "I'm overly impressed by what you have. Would you like me to stop telling you that you're brilliant?"

Sherlock pouts. "No."

"Then remove Rule Number Thirteen."

Sherlock scowls and does so.

When they return to 221B after Dartmoor, Sherlock creates a hard copy of the rules. He hand writes them all on a large sheet of paper and attaches it to the refrigerator, but they never think of consequences. They never really have to because both men keep to the rules.

After the Reichenbach case, John makes Rule Number Thirteen: That Sherlock smile and let people take his picture. Sherlock doesn't like it, but he does let John add it to the list.

After John gets Sherlock out of jail during Moriarty's case, John adds another rule.

"Don't be an arse in court," he says on the cab ride home.

"Is that a rule?" Sherlock asks.

"Yes. I'm adding it to the rules when we get home."

"No fun, John."

"Bailing you out of jail was no fun either, Sherlock."

"Where is your sense of adventure? When I met you you'd have probably done anything, even if it meant going to jail."

John shakes his head. "You're right. I just haven't had to shoot anyone lately."

"You wouldn't have gone to jail for that," Sherlock says. "But fine. If you must add it, do so."

John nods.

Days later, when John punches the police chief to defend Sherlock, Sherlock smiles as John gets pushes against the car next to him because he knows that John would do anything if it meant going to jail only for him.

After the fall, John goes back to 221B to tell Mrs. Hudson what happened. He can hardly move or speak, but he tells her the whole story and lets her hold him as he cries. When he's finished, he goes upstairs to be alone for a while.

Somewhere in the middle of the night, John grows hungry. He goes downstairs and to the refrigerator, staring at the rules list as he opens the fridge.

To his surprise, there are no body parts in the fridge. It hurts him to see that, that for the first time since he made the rule, there are no body parts in the fridge.

When he goes into the living room, he takes a deep breath and sits in his chair. He bends over to adjust his socks, when he sees a red line circling his chair. How long has this been here? he wonders.

He thinks back to how Sherlock deduces things, and in his own way, he realizes the line has been there a long time, he just failed to notice. His chest aches at the thought that Sherlock did something he saw as considerate, and John didn't even notice.

John's phone rings a while later and it's a woman he dated a few months ago. He doesn't answer it, he doesn't want to talk to anyone, and at that moment, John realizes there have been no women since Christmas. Only Sherlock.

Over the course of the next day, John realizes Sherlock obeyed every single rule on the list and never argued over any once they were added to the list. John cries over this. Sherlock was the perfect flatmate, John thinks.

Then John grows angry.

Because of the stupid list, he never asked Sherlock how he felt through this whole thing. He never asked if Sherlock was ok or if he needed anything because he was obeying the rules. John stands from his post in his chair and stomps over to the fridge, yanking the sheet of rules off and nearly ripping it.

He wants to rip it but he doesn't, instead he holds it and reads it as he cries. He traces his finger over Sherlock's sketchy handwriting and smiles at the funny ones.

John holds it up towards the light and notices there's writing on the back. He grows curious and turns it over, seeing a numbered set of five rules in Sherlock's handwriting.

Be good to John.

Be nice to John.

Listen to John.

Obey John's rules.

Love John.

John can't stop tears from rolling down his cheeks at number five. He falls to his knees clutching the piece of paper and cries there for an hour longer. Mrs. Hudson finally finds him and takes John down to her flat, making him eat and sleep.

Three years later, Sherlock returns and John welcomes him with open arms. John is far too happy to be upset about what's happened, he is just very relieved Sherlock is alive.

Months after the return, John brings up the rules.

"God," Sherlock says. "Are you still going to make me follow the rules?"

John shakes his head. "Just one, if you're up for it."

Sherlock gets a confused look. "Which one?"

John bites his lip and looks at Sherlock through his lashes. "Number Five: Love John."

Sherlock is instantly shocked. He gasps and his eyes grow wide. "I didn't…I didn't know…"

"I saw them after you…died."

Sherlock nods. He looks back at John and without thinking, he leans over and kisses John.

"So, you're up for it?" John asks when their kiss ends.

"Only if you obey the same rule for me."

John nods. "Deal."