Detective Inspector Lestrade was getting very tired of making the long trek over to Baker Street every time there was a crime that strayed beyond the too familiar. The fact that Baker Street's resident genius knew he was irreplaceable enough to insist that Scotland Yard come to get him on each and every occasion made it worse. Lestrade sighed, not quite able to wish he'd never met Sherlock Holmes, but getting closer every minute.

Today, he heard shouting before he even entered the door. More alarmed than he wanted to let on, Lestrade almost kicked the door down to get inside; what if some criminal with a grudge against Sherlock had found their way here? Before he could, however, Mrs. Hudson emerged from the front door, looking worried.

"Oh, Detective, I'm sorry!" she said as she almost walked into him. "I was just going out to do a bit of shopping, get some milk, everyday things, you know."

"Uh, yes," Lestrade said uncertainly. "Listen, is everything all right in there? It's a bit loud."

"Oh, that," Mrs. Hudson said, looking up at the first floor window anxiously. "They're having a bit of a domestic. I don't really know why, but they do sound angry don't they? I hope they don't ruin one of my walls again." She waved goodbye, leaving Lestrade standing outside, looking up at the window himself. The shouts were growing louder now; people passing by on the street were starting to look up. He sighed and resigned himself to heading up the seventeen steps.

Neither Sherlock or John seemed to realize he was even there. They were too absorbed in yelling at each other from opposite sides of the sitting room. Over one another, really. They'd obviously long since passed the point where they actually listened to what the other was saying. Lestrade simply stood there, trying to get a grasp on what exactly they were arguing about.

"Why do you even bother protecting it if you know I can just get past it anytime I want?" Sherlock said, trying to sound logical while at the same time out-shouting John.

"It's the principle of the thing, Sherlock! It's. MY. Laptop. Not anyone else's and definitely not yours!" John yelled back, red in the face. Lestrade watched in silent fascination. Sherlock and John didn't fight. They'd been flatmates for eight months now and in all that time he'd never seen them fight. Sure, they'd argue until everyone around them was sick of listening. They'd banter for the entire day if they could. Sometimes they'd give each other the silent treatment, if things got really bad. But never an actual fight.

"Maybe I should just move out then, if you can't comprehend the slightest thing about privacy!" John yelled.

"Yes, maybe you should, if it means that much to you," Sherlock shot back, and that's when Lestrade decided this had gone too far.

"All right, now, come on," he said. "Let's not take this too far."

They both turned around and looked at him. "When did you get here?" Sherlock asked.

"Not that long ago. Only a couple of minutes, really."

John sighed, "You heard all that, didn't you?

"Well, enough of it, anyway," Lestrade said. "You don't really mean that?"

"Oh, I do," John said, his anger flaring up again. He pointed at Sherlock, "He keeps using my laptop. Going through my files. It's password protected! He keeps guessing them."

"It's not really that difficult," Sherlock said under his breath.

John threw a hand up in the air, "See? He doesn't even get it!"

"Well, really, John, I solve crimes for a living and knew everything about you after meeting you for two minutes, did you really think I wasn't going to be able to guess your laptop password?" Sherlock asked, his tone biting.

Lestrade had to admit Sherlock had a cruelly logical point. There was a reason he stored his own computer in a state-of-the-art safe in Scotland Yard when he wasn't using it. Still, everyone had the right to not have their flatmate go through their computer.

"Sherlock, do you really need his laptop? I know you have your own."

"Mine was in the bedroom!"

Lestrade sighed. He knew he was dealing with a child in many ways. It wouldn't be the first time he had to lay down the law with Sherlock.

"All right, listen, you two. John, is there anywhere you can keep your laptop where he won't get to it? Your bedroom's on the second floor, isn't it?

John rolled his eyes, "He'll go up there and get it just to spite me, you watch."

"John, if he won't even go to his bedroom to get his laptop, do you really think he's going to climb a flight of steps to go get yours?" Lestrade argued logically. Sherlock smirked; they all knew he was exceptionally lazy when not on a case.

John glared at them both before conceding, "No."

Lestrade smiled, "Good. Now, Sherlock, you know as well as I do that there aren't that many people who would enjoy living with you the way John usually does. Do you really want him to move out?"

Sherlock flung himself onto the sofa and shook his head without looking at either of them.

"And, John, you've told me yourself you didn't know what you would have done if you hadn't met Sherlock? And now you want to move out?"

Defeated, John shook his head too, "No, I don't. But we need some ground rules!"

"Well, start with, no using each other's laptops," Lestrade said. "Does that sound good?"

Sherlock glanced over at them and sighed theatrically, "All right, fine."

"See?" John asked. "That wasn't so difficult, was it?"

Lestrade gaped at him, "That's it? No other rules you want to lay down? No experiments in the fridge, no gunshots in the flat?"

"No, I think that's it," John said. Sherlock grinned in that sideways way he had and Lestrade shook his head.

"I knew there was a reason you were the only person who could last more than two weeks here," he muttered. "Anyway, I've got a case for you, if you want it. Cabbie found dead, cab full of dead people's credit cards. Coming?"

Sherlock and John glanced at each other, then rushed to grab their respective coats without another word. Lestrade followed them out the door. Just add referee to my CV, then.