Something messy.

John had known about Sherlock for a while now. He also knew that he would eventually end up dead, and that Sherlock would be the one to kill him. But despite the fact that his serial killer flat mate was only leaving him alive to avoid the boredom of living alone or the inconvenience of having to find a replacement, he couldn't leave. He was addicted to danger and living with a killer, who had promised to kill you one day was a source of such danger too good to pass up. John looked up as the door opened.

Sherlock studied John as he entered the room. Was it time? he asked himself, as he always did. No, not yet, he decided. As he walked into the sitting room, he kept his eyes locked on John's enjoying how the other man was clearly incapable of looking away. The moment he released him, John jumped to his feet.

"Do you want some tea?" he asked heading for the kitchen.

Sherlock smiled. Things had gotten so much more interesting now that John knew. It was as if everything they said were merely euphemisms for the essential question and answer: 'now?/not now!'. He nodded. "That would be nice," his grin was turning a little predatory, but he no longer bothered to conceal it.

John froze as he turned and saw the smile on Sherlock's face. He swallowed convulsively. Maybe today would be the day then. "Right. Ill just get us some..."

"Good," Sherlock stretched before slumping down in his chair.

John brought Sherlock his tea, before sitting down across from him, sipping his own. "Well?" he asked. He knew Sherlock would understand what he was really asking. But Sherlock so enjoyed toying with John and just raised an eyebrow as if echoing his 'well?'

"Well...what are your plans for today?" he knew Sherlock was just playing with him but he needed to know if he had finally decided.

"Something messy..." Sherlock sat thinking for a while. "Actually, I could use your help..."

John nearly spit out his tea at the hidden meanings in Sherlock's statement. It could mean anything from an experiment to his messy death. "What would...? Why do you need my help? What with?"

"Well," Sherlock shifted a little in the chair, considering how to phrase it. "There's this 'profile' being handed around making it difficult for single men at a certain age to move unnoticed in some locations..."

"What profile? Is it of you?" John wondered if Sherlock's killing had finally been noticed. As of yet no one had even suspected that the deaths were linked. He didn't know whether he hoped that they were finally going to catch him or not.

Sherlock chuckled. "Nothing that particular. Just specific enough to be inconvenient for my 'work'."

"Oh" John realised he was a little disappointed. Despite his choice to continue living with Sherlock, some part of him must be hoping that someone else would put a stop to this, before he was the one being killed. He thought about what Sherlock had said. "You said single men. You want me to go with you?"

"Yes, that would be a great help."

"You want me to help you kill someone."

Sherlock feigned shock. "No! Nothing like that. I just need you to be my 'date', when I go out observing."

John considered for a moment. He didn't want to be a part of someone's death but knew that if he refused Sherlock too often he would end up being next, so eventually he nodded his head. "I'll go with you I guess.."

"Perfect," Sherlock jumped to his feet. "We'll leave in an hour, wear something dark and tight."

An hour later John was walking beside Sherlock through the London streets. Sherlock's arm was around him as if they were a couple. "So where are we going?"

"Out," Sherlock smiled enigmatically as he steered them towards one of the few nightclubs he hadn't visited yet. Once inside he led John to the bar and bought him a pint, sticking to tonic water himself. He scanned the crowd.

John stood awkwardly by Sherlock. Not really knowing what he should be doing. "Um, so who are you looking for?"

"I don't know yet," Sherlock put his arm around John's shoulder, pulling him close. He stood like this for a long time, just observing, then he nodded his head in the direction of the dance floor. "See the woman in the purple shirt and tight jeans?"

"Yes..."

"She's just been dumped by the fourth, maybe fifth boyfriend in as many months. She's been accused of being too boring and predictable. So tonight, she's determined to do something stupid and possibly a bit dangerous." He chuckled. "I think we can help her with that."

"We... I thought you said I wasn't here to help kill anyone." John looked at the woman. He knew he couldn't stop Sherlock and if that was who he was going to kill she was going to end up dead no matter what.

"No, no," Sherlock turned and looked him up and down, straightening his clothes and brushing his hair back. "You just have to stand here and look adorable. You think you can manage that?"

John looked at Sherlock confused but nodded anyway. He once again felt awkward just standing there but tried to look natural.

"Perfect." Sherlock planted a dry kiss on his cheek before turning to the bartender to order a small cocktail. When he got it, he took it and his own drink in his hands, circled the dance floor and approached the young woman. He offered her the drink, spoke a bit to her, leaning close, so she could hear him over the music and then pointed to John. The woman looked at him across the dance floor, smiled and blushed.

John smiled back. He still wasn't completely sure what Sherlock was doing but hoped he could leave before it got murderous.

The woman nodded, and Sherlock put his arm around her shoulders and led her over to John. "John," he said. "This is Clara. She likes to be watched. Clara, this is John. He likes to watch." The girl turned even more crimson as she held out her hand to John.

John took her hand. He knew he was turning red too and was a little annoyed at Sherlock's inability to feel embarrassment. "Um, so are we going somewhere?" he asked a little worried about the answer.

"Home!" Sherlock put his arm around John's shoulder, his other one still around Clara, as he led them to the exit. He soon got them a cab, and letting Clara get in first, placed himself in the middle of the seat.

John found the ride back to their flat extremely uncomfortable. Sherlock was holding his hand, their fingers entwined, while he was kissing Clara's neck. Was Sherlock going to kill her in their flat? Would he want Johns help? Was John really going to let Sherlock kill a random girl? He was so lost in his thoughts that he didn't notice they had arrived, before Sherlock nudged him.

As they got out of the cab, Sherlock turned to John. "You pay," he said with a wink and then escorted Clara through the door of 221b Baker Street.

John quickly gave the money to the cab driver before hurrying up the steps. He nearly ran up the stairs but was met by Sherlock in the door. Behind him, John could see Clara sitting on the sofa, looking a little nervous. Sherlock leant close and whispered in his ear. "You can go up to your room now. I'll make your excuses."

As John climbed the stairs he heard Sherlock speak as he closed the door. "John won't be joining us, but I'm sure we can manage without him."

He walked slowly up the stairs ears both straining to listen and trying to block out all sound. When he reached his room he sat on his bed and waited. For Sherlock to either finish or sleep. He never heard a sound and at some point he drifted off.

When he came down the next morning, Sherlock sat in his chair as languid and content as an alpha lion surveying his kingdom. He greeted John with a cheery "Good morning."

John looked for any sign of a murder or body but there was none. Of course Sherlock would not leave evidence. "Good morning... So how was your night?" John was curious despite himself.

"Delightfully messy," Sherlock answered stretching. "Thank you for your help. You were perfect."

"It doesn't look like it was messy." John hadn't really meant to say that. He wanted to forget that last night had ever happened, but somehow, he couldn't help himself. "I mean... Would you like some breakfast?"

Sherlock nodded in response to the question and then added with a humorous frown. "I can actually clean, you know."

John snorted. "Yeah only when you could go to jail if you don't, do you finally clean up after yourself." John had gotten toast for the two of them and handed one plate to Sherlock.

"Jail can be a very efficient motivator, much more so than your scowls," Sherlock agreed.

John did scowl at his. "Will it happen today?" he asked the question he had asked every day in one form or another since Sherlock promised to kill him.

"Not today," Sherlock hummed. "I'm feeling far too content today."

John breathed a sigh of relief. "Okay well I have to go shopping later. Anything you need?"

When Sherlock didn't answer John stood and left. He wondered what would happen when Sherlock decided it was time. Would he even get a warning? If not, today could actually be the day, he supposed.

Sherlock used the time, John was away, to get rid of the final leftovers. He hummed to himself as he worked. Last night had been really... successful.

When John returned Sherlock was still in a good mood. "Why are you so happy? You have killed other people before but you're never still smug about it this late in the afternoon."

"Last night was special. I hadn't expected it, but bringing you along made it all so much more ... pleasurable."

"Does this mean you want to bring me more often or you want to try having me as the dead body?" John questioned not sure which he would prefer.

"No, John." Sherlock chuckled. "If you ended up dead, I would just have to find a new flatmate. And I seriously doubt I could find someone as accommodating as you. Your are safe... for now."

John smiled a bit. Sherlock did say for now, but if he continued to do as Sherlock said, he might not end up dead afterall. But then again, maybe there were worse outcomes.

It was almost a week, before Sherlock asked John to go out with him again. John agreed and was once again dragged off by Sherlock with no knowledge of where they were going.

This time they were going to a different type of club. The target turned out to be a young man, hooked on cocaine, desperate to make a little extra money to pay off his debts. It was almost too easy. Sherlock didn't even have to use John as bait, but left him at the club.

After John had watched Sherlock leave with his unlucky victim he sighed and went to call a cab. He hoped Sherlock wasn't bringing the man back to the flat as he just wanted a cup of tea and not walk in on a murder in progress.

Knowing that John might show up, Sherlock had made sure to lock the door to his room. The young man was easily tempted by his own stash, and was kept nicely quiet and passive. Hearing John move about on the other side of the door, was surprisingly thrilling.

John was glad of the empty flat but wondered where Sherlock could have taken the man. He was heading up to his room when he heard it. A small sound barely noticeable. It was someone moaning and it definitely came from Sherlock's room. Walking over John raised a hand and knocked hesitantly. "Sherlock, have you got that man in there?"

Sherlock froze. 'Oops!' he thought and almost giggled. "Not anymore," he called.

John gulped. "You already... He's gone?"

"Yes," Sherlock answered, grinning. This wasn't strictly speaking true, but it would be in a manner of minutes.

"Then let me in." John knew he had heard something and suspected that the young man was still alive in there. He could not just leave it like this. Maybe there was still something he could do...

"Not right now..." this time Sherlock could not suppress a little giggle. "I'm... not decent." He tightened his grip, anticipating the rush.

"Are you laughing? Sherlock, are you actually killing a man while laughing and talking to me?" John was at a loss for how to deal with this. He wasn't sure whether to laugh at the absurdity of it all or break down the door and try and save the young man.

"No," Sherlock's voice cracked with pleasure as the moment came and relief surged through him. Once again, John had only increased the experience.

"Sherlock!"

John waited almost a minute and was about to give up and leave, when the door finally opened to reveal a grinning Sherlock. His hair was sticking out at odd angles and his cheeks were flushed. He was a little out of breath as he spoke. "Yes?"

"I can see a foot" John stated staring past Sherlock into the room. "There is a dead man lying on your floor and you killed him while having a conversation with me!" John thought he might be in shock as he suddenly burst into giggles.

Sherlock's sheepish look was not very convincing. "Next time, I can put a sock on the door handle, so you'll know I have company. Will that make you feel better?" Sherlock laughed at the look on John's face.

"Oh god Sherlock. I don't know what to do." John said as his laughter died down. "Should I pack up my things and leave? Would you kill me if I tried? Should I just give up and follow you while you kill people?" John was looking at Sherlock, begging for some reasons or at least some sanity in all this.

"It's not a question of what I will do John. It's all about what you want. It's time for you to decide." Sherlock turned and went back into his room, leaving the door open.

As John stood there, he greatly suspected that Sherlock would kill him if he intended to leave and somehow he couldn't imagine living without Sherlock and their adventures. On both sides of the law. His decision made, he walked into Sherlock's room.

Sherlock was straddling the young man's chest, gently closing his eyelids with the tips of his fingers. "He was really quite pretty. Shame about his nasty habit." He gestured to the bedside table, where the remains of several lines of cocaine still lay scattered on the mirror.

John just nodded and watched as Sherlock studied the body. After a while he got up and opened the window. He looked out and when he was sure there was no one in sight, he turned to John. "Can you give me a hand here?"

"Uh yeah. Are we throwing him out the window?" John hoped this wasn't how Sherlock usually disposes of bodies. It didn't seem like a good place just outside the flat.

Sherlock chuckled. "No, stupid. I'm taking him down the fire escape. No need to risk running into our dear landlady."

"Oh right" John supposed that made more sense. He helped Sherlock lift the body up and ease it out the window. John prayed he had made the right decision.

Once they had the body outside, Sherlock picked it up. "Thanks, I can handle it from here. You should get to bed now."

John agreed and went up to his room. His tea stood, cold and forgotten on the table outside Sherlock's room.

The next morning John woke up thinking it might had been a dream. But then he remembered how he had basically agreed to do help Sherlock in his 'work'. He sat up with a jolt. How had this become his life?

Sherlock was practically giddy that day, joking and humming, as he flitted about the flat. He even made lunch for them and told John amusing stories about Mycroft as a teenager, while they ate.

John was enjoying Sherlock's good mood, while trying not to dwell on why he was so happy in the first place. But he couldn't let it go, and finally he asked: "Why are you so much happier now than before when you killed people?"

Sherlock considered. "I guess it's because of you. It's really nice to have someone to share this with."

John smiled, but then he remembered what exactly they were sharing.

Sherlock studied him. "How do you feel about it?"

"I...I should feel worse." John answered truthfully. He knew it was bad to feel this guiltless after someone had died almost in front of him the night before.

"I used to feel that way," Sherlock said nodding. "Don't worry. It won't last long."

"Do you think I'll end up killing like you?"

"That is entirely up to you," Sherlock looked serious. "What do you think?"

John considered for a moment. He remembered laughing at how Sherlock killed the man. And he felt fairly neutral about it. And after all, he had killed before, just never like that. In the army or on cases, there had always been a reason. Never just killing for the sake of killing. "I...I think I could but I don't know if I will."

"That's fine," Sherlock smiled. "What do you feel like doing tonight?"

John considered for a moment, and then something clicked. He turned to Sherlock. "Something messy," he said with the smallest hint of a smile.