He woke early in the morning to find Sherlock dozing, lying on his back with his hands folded across his chest, still fully dressed and looking entirely composed. As John looked at him he opened his eyes, immediately straightening his chair and looking wide awake.

"Ready for another day, Doctor?"

John stretched as far as his shoulder would allow and gave his back a cursory rub. He felt surprisingly groggy considering he hadn't had anything to drink the night before. He yawned, and said, "Eh, yes. I think so."

He stuck with tea and toast for breakfast, not feeling up for yet another nightmare meal. To his surprise Sherlock ordered the same.

"So, you do eat, then."

"I would hardly call it food. Call it fuel. Besides, I think I'm getting somewhere."

John gave him a blank stare. "Sorry? Getting where?"

"The case, John. Berserking replicants, remember?"

"Oh." John rubbed his face in an effort to wake up properly. "Sorry. Have you solved it? Sitting on a spaceship?"

Sherlock smiled briefly. "Not quite. But I believe we have some good leads. We'll have to make a few visits when we arrive."

John couldn't ignore the 'we' in the statements. "You're serious then, about me coming along?" Only when he finished the sentence did he realise that sounded far too needy. "I mean," he added, clearing his throat in an effort to salvage his pride, "you seem pretty self-sufficient."

"I like company when I'm on a case, and I work better when I have someone to talk to. Talking to my communicator just attracts attention."

John looked at him, wondering if that was a joke or not. It was hard to tell from the guy's dead-pan expression. He still felt groggy, and not ready to endure Sherlock's razor-sharp wit. He fervently wished someone would bring him his cup of tea.

"So I'm basically filling in for your communicator."

Sherlock gave him a sly smile. "Relax, you're doing fine."

Before he could think of anything to say back the space hostess arrived with their breakfast. John seized the opportunity for a distraction as he took his plate.

"Thank you. Listen, we need to book in for our VK tests. Can we do that now?"

The girl produced an electronic organiser. "Sure. I've got an open slot at ten. And then another one at twelve?" She looked across to Sherlock to see if he would be happy with that time.

Sherlock shook his head. "No need. I'm exempt."

John turned to Sherlock in astonishment as the girl looked at him dubiously. "Sorry sir, but nobody's exempt."

"Well, I am." He reached into his jacket and produced an official-looking document in a leather wallet from his inside pocket. John thought the leather looked real; if so it would have cost a small fortune. Sherlock passed it to the hostess, who studied it for some time, making a few notes in her organiser before giving it back to him.

"I'm sorry sir, but you understand I will need to get this checked."

"Naturally."

Sherlock smiled as the girl walked off, and John took the wallet off him. "What's this?"

When Sherlock didn't answer he took a good look at the document. It looked very official, entirely genuine, and proclaimed that the named bearer was exempt from any and all forms of replicant testing. He passed it back to Sherlock.

"Is that real?"

"Yes."

"You said you were human."

"Hm. And I don't see why I should keep on having to prove it."

John stared at him in some disbelief. "Us mere mortals have to."

Sherlock shrugged as he put the thing back in his pocket. "And I don't."

"But how did you get that? I didn't even know there was such a thing as exemption from VK tests."

Sherlock just raised his eyebrow and pointedly turned his attention to his toast, leaving John hanging with more questions than answers. In a way he'd been looking forward to the testing, to some official confirmation that Sherlock was indeed not a replicant. For all the pomp of the document that Sherlock had just produced it hadn't actually stated that the bearer was human. The fact that he needed the document at all made John somewhat uncomfortable.

He brushed the thought aside. It was probably more common than he realised in the circles in which Sherlock moved, he'd just never come across it in his more mundane existence. He tried to reason away the fact that the space hostess hadn't either – she looked very young and was probably new. Holding that thought he started on his breakfast.

-ooOoo-

Compared to the previous day, most of the second day on the ship proved positively humdrum. As John turned up for his VK test it became obvious that nothing was going to plan and that the day's schedule had already been put into disarray by a number of overrunning tests, added to by faulty equipment. When he made to go back to his seat he was told he needed to remain in the queue or risk losing his place. In the end he managed to get into his old army mindset of hurry-up-and-wait, sat down and passed a couple of hours in a zen-like state.

When his turn finally came, an hour after lunch, the test itself was almost a formality. With his naturally high level of empathy it was obvious to even the most untrained observer that John was no replicant. He returned to his seat, certificate in hand, feeling somewhat deflated. Sherlock hadn't moved from where he had left him three hours ago, hunched over his communicator. He looked up when John arrived.

"Congratulations, Doctor, you are officially human."

John smirked. "Thanks. I need a drink after all that. And some food."

Sherlock straightened out his legs and sat up. "Are you brave enough to revisit the bar?"

"I'm sure we'll survive."

The bar was as bad as the day before, but at least this time the barman didn't attempt to swindle them, and the rest of the visitors left them alone. The group of miners was there again, or maybe they were still there, but they made an impressive effort of pretending that neither John nor Sherlock existed. John even managed to obtain a couple of tiny packets of real peanuts to make up for his lost lunch, which he considered a major victory.

Sherlock showed him some of the messages that he had received from the Mars police, more gruesome images, and long lists of names, dates and contact details of anyone and everyone that had any connection with the replicants as well as the murder victims. It seemed the Mars police force, although enthusiastic, was rather scattergun in its approach to addressing the case.

"How do they expect you to be able to do anything with that? It's just reams and reams of names. Aren't they being a bit overzealous?" John was staring at Sherlock's screen as the list of meaningless details scrolled past. They might as well have sent Sherlock the entire population roll of the colony, it would have been quicker.

Sherlock was totally non-committal. "Hm."

"Oh, honestly, Sherlock. Where do they expect you to start? There's far too much information here."

"There is no such thing as too much information, John. What we are looking for is patterns. And there are several. They are just hard to see when it's presented like that." He took the device back and looked over the list again, then sighed. "I need a wall."

John stared at him, waiting for an explanation, but since none was forthcoming they drank in silence for a while. Sherlock was growing increasingly restless, occasionally glancing at the screen, scrolling up and down, alternated with tapping the table irritably with his long fingers. Suddenly he threw his hands up in exasperation and almost shouted, "Oh, it's no use. I need to do something."

He jumped up and walked off, leaving John not a little bemused with his own drink and half a glass of quality whisky. In the end he decided not to follow Sherlock, but calmly finish his beer instead. When he was done Sherlock still hadn't returned, so he followed the beer with the leftover whisky. Then he ate the peanuts and made his way back to his seat. Sherlock was nowhere to be seen.

Twenty minutes or so later Sherlock re-emerged, looking – and smelling – as if he had just had a shower.

"Your hair's wet."

"A brilliant observation, Doctor."

"Have you just had a shower?"

"Clearly."

John's mind reeled. The cost of water on these flights was astronomical. Most people got by with a quick wash in the morning and a change of underwear. He'd never heard of anyone taking a shower on a Mars shuttle. In fact, he didn't ever know where the showers were on this flight.

"I'm beginning to think that whoever hired you for this case is paying you too much."

Sherlock raised his eyebrows. "I needed to clear my head."

And that's it, John thought. The man needs to clear his head so he spends the equivalent of a week's wages on a shower. Different worlds, indeed. "Most people would have stuck with the whisky. Which I drank, by the way."

Sherlock gave a brief laugh.

-ooOoo-

This time John couldn't manage to convince Sherlock to accompany him to he cinema, so he went to the early evening show on his own. Today's offering was a romantic comedy and although he enjoyed it he was glad Sherlock hadn't come. He'd hate to think how he would probably have ripped it to shreds just by looking at the opening credits.

The day slowly receded into night, and after another gruesome meal John found himself dozing off again. Sherlock had been entirely uncommunicative all evening, having given up on his communicator in disgust halfway through and tossing the thing into the luggage compartment, and now seemingly unable to settle to anything for more than half a minute. His almost constant shifting around reached a peak at around a quarter past eleven, ship's time, at which point Sherlock jumped up, squeezed his way past a sleepy John and charged off along the aisle.

John recovered his blanket and rolled onto his good side once more, groggy with sleep. Every so often Sherlock would stride past, his long legs steadily pacing across the floor, apparently doing a continuous circuit of the whole ship. John fell asleep watching him pass by at regular intervals, once more contemplating the strangeness of him, half wondering if he was real.

-ooOoo-

By the end of the third day on the ship John was nearly ready to strangle Sherlock, and almost decided he would have nothing else to do with him.

He was convinced Sherlock never slept at all during the night, as his army training had made him a light sleeper and he would have certainly noticed him squeezing past him to get to his chair. In the morning he found Sherlock back in the games room, doing some kind of intricate physics experiment on the air hockey table that involved at least twenty glasses from the bar more or less filled with a variety of drinks positioned in a seemingly random pattern across the table and Sherlock kneeling in front of it, flicking the puck with his index finger time and time again, apparently aiming at aligning glasses and puck in such a way that the thing went into the other half's goal with a single flick after bouncing off each glass in turn. The place smelled a bit like a brewery.

John watched him for a good while before Sherlock even noticed his presence, and marvelled at the bloke's misplaced focus and energy.

"That's one way to spend your pocket money," he said as Sherlock put another coin into the machine to keep the air flow going.

Sherlock gave him a quick glance over before responding. "Don't be dense. I picked the lock on the cash box of course. I don't carry coins."

Of course not, John thought. He could hear the jangle of metal as Sherlock was moving about, and wondered exactly how much had been held in the machine, and whether Sherlock was going to return the money to its rightful owner.

With one final flick Sherlock made the puck follow a perfect course among the glasses and land in the opposite goal with a satisfying clunk. Mission accomplished, he straightened up and looked at John again. "Well, that was dull." He looked at the table and added, as an afterthought, "Drink?"

John gave a dry laugh. "I don't know. What have you got?"

Sherlock surveyed the table. "Two types of whisky, dry gin, gin & tonic, straight tonic, some awful cider that I wouldn't feed to my worst enemy, but it's gone flat anyway so you wouldn't want it, two different kinds of stout, a couple of lagers, vodka and orange, straight vodka, straight orange, three different types of red wine, dry white, sweet white, two glasses of rosé and a margarita."

John smirked. "Sherlock, it's breakfast time."

Sherlock looked at him blankly for a moment, and then said, "You'll want the orange then." He passed the glass to John who accepted it with only a brief observation on how surreal his life was becoming.

"Twenty-one different types of drink?"

"Obviously the different densities of the drinks affect the physics of the interaction between the glasses and the puck, especially with the thin glass they use in this place. It wouldn't be much of a challenge otherwise."

John just raised his eyebrows. He wasn't sure what the right answer to a statement like that would be.

As he was sipping the orange juice Sherlock disappeared into the bar, only to emerge half a minute later with one of the miners, the one who had attacked them with a knife of all people. The man was as white as a sheet and trembling slightly. When he recognised John he went an unpleasant shade of green. John just stared, non-plussed, but the bloke clearly interpreted this as a silent threat as he began to shake even more. Sherlock steered him to the air hockey table, hand lightly resting on the man's shoulder.

"Clear it for me."

The man briefly surveyed the table, cataloguing the amount of alcohol on display. His expression went from dread to disbelief. "Wha- what?"

Sherlock sighed. "You heard what I said. Clear it. I have no further need for it." He let go of the man, giving him a slight push in the direction of the table as he did so, and stepped back. As if on cue the timer on the table ran out, the air flow stopped and an eerie silence suddenly descended upon the scene. John briefly wondered if that was a coincidence, or whether Sherlock's sense of dramatic timing was really that good. Given the wicked half-smile that was playing around Sherlock's mouth he was inclined to go for the latter.

The miner stood there a moment, a comical look of indecision on his face, and then leaned forward and grabbed five of the glasses in one go. He gave John and Sherlock one more confused look to see where the catch was, then returned to the bar as fast as he was able to without dropping his load.

"Be sure to come back for the rest," Sherlock called after his disappearing form. John sniggered, and Sherlock gave him a surprised grin. "Well, what else was I going to do with it?"

John shook his head. "Coming for breakfast?"

"Dull," was all the response he got to that, but Sherlock followed him back to the seats anyway.

As the morning wore on John began to regret ever going to find Sherlock. Without any apparent new leads coming in on his communicator Sherlock grew increasingly agitated. He couldn't settle to anything, seemingly unable to regain the quiet composure he had at the beginning of the flight just looking at the stars. When John suggested it as an option Sherlock looked at him as if he had gone mad.

"They're just stars, John. They don't do anything. They're completely irrelevant to the case."

"But – " John managed, a bit thrown, "You've spent hours staring at them in the last two days."

Sherlock gave him a blank stare that spoke volumes about how far his reality and John's were really separated. "I was thinking."

After that things went from bad to worse. Sherlock now focused on the in-flight magazine, scathingly taking apart every single article it contained. Although it was funny up to a point it became grating after a while, especially when Sherlock then moved onto the book that John was trying to read, making insinuations not just about the book itself, which John wholeheartedly agreed with, but also about any person who would choose to read such rubbish and their inferred intellectual prowess. At this point he cut Sherlock off.

"Yes, thank you, Mr. Holmes. It's just a bit of light reading. It doesn't reflect my life history and choices, nor my level of academic achievement."

Sherlock shut up, his raised eyebrow the only indication that he disagreed distinctly. He sat quietly for a moment, then abruptly jumped up, squeezed past John and disappeared down the aisle.

The rest of the afternoon was spent trying to deflect Sherlock's snide but accurate observations every time he came past on his rounds of the ship. He reminded John more and more of a bored child, especially when the children across the aisle also began to act up. The parents were finding it increasingly difficult to control them, and the next time Sherlock passed by John could barely make out what he said over the screaming.

He was very close to telling Sherlock where to stick it when the taller man suddenly stopped and made his way back to the screaming children. He observed them for a while, as if they presented an unusual and interesting problem, and finally said, "They're bored."

The mum sighed an exasperated sigh at him and nearly shouted, "Of course they're bored. We ran out of things to do yesterday, there's nothing left. It's not like I can keep chucking money at the games machines." She was holding on to one of the kids, trying to stop him pulling his sister's hair. Judging from the girl's screams she was only partly succeeding.

Sherlock looked at the mother a moment, then poked a long finger into the boy's shoulder, who finally stopped torturing his sibling and turned round. Sherlock took a coin from his pocket and flicked it up into the air, the shiny metal spinning a slightly too-slow trajectory until he suddenly snatched it out of its arc.

"Air hockey?"

When John went to check twenty minutes later he found Sherlock and the two children completely engrossed in a highly complicated version of the game which involved a whole new set of rules that were apparently being evolved on the spot. The darts score board had been taken over for what appeared to be a three-tiered hierarchical scoring system which John could make heads nor tails of. To his total surprise Sherlock seemed to be enjoying himself immensely.

"The cognitive abilities at this age are remarkable, John. Their adaptive speed along with their high retention allows for levels of complexity in their competitive interactions that I had not previously appreciated. Combined with an astounding flexibility in thinking together with a strong determination for attainment this is proving fascinating."

John thought a moment, translating. "You mean they are playing an imaginative game and cheat like hell to win at all cost."

"And they are remarkably easy to run," Sherlock added, not put off by John's sarcasm.

John noted the two glasses of juice and the packet of biscuits on the side table. He shook his head with an incredulous smile. "Well, I'd better leave you to your experiment. Wouldn't want to influence the findings."

When he returned to his seat the children's parents were already fast asleep.

-ooOoo—

The next morning John woke to find Sherlock fast asleep next to him, still looking composed even in complete relaxation, arms neatly folded over his chest and the only concession to his state of rest being the disappearance of his jacket. John looked him over, noting that there was very little of him underneath the posh clothes, all long arms and legs attached to a wiry frame. All he could think was that Sherlock could do with feeding up a bit.

Breakfast came and went and still Sherlock slept, his slow, deep breathing somehow incongruous with his usual animated energy. John returned to his book, wondering when Sherlock might wake up.

Ten minutes before their entry into Mars orbit Sherlock suddenly opened his eyes and sat up. John couldn't help himself. "Good morning, sleepyhead."

Sherlock frowned at him. "I'm not sleepy."

"You must have been. You slept for ages."

Sherlock gave him a blank look. "There was nothing left to do. It was a sensible strategy to preserve my sanity."

John had to remember to close his mouth. "Oh."

He didn't have all that much time to be surprised, though, as the lights for seatbelts were already going on and the space hostesses were handing out the customary chewing gum. John smiled as the children next to him grabbed a handful each. They seemed none the worse for an evening at the hands of Sherlock. He briefly wondered how the game had finished.

Re-entry was nowhere near as traumatic as lift-off had been, but then John was an awful lot calmer this time. To his relief he didn't black out again, although he still felt queasy as they were turning over the crater towards the space port for touchdown. Sherlock, he noted without surprise, looked relaxed, bored almost.

He had to look away from the window when the ship turned into the sun glinting off the polymer dome that covered the crater, bathing the interior in a bright orange glow. The light was nothing like he had ever seen on Earth. There was something about the intensity and colour that was entirely alien, soft, much like liquid honey in the way it was draping itself across the interior of the ship.

So different to the Moon, he thought, where the sun had been just like it was on Earth; harsh, clear, no-nonsense. He'd never felt far from home on the Moon, but now the realisation of being on another planet was so clear it was almost physical.

John's musings had distracted him to such a degree that he was shocked to feel the ship touch down, the jolt as the rear wheels hit the runway shaking him back to reality. Within minutes they were parked up at the airlock, waiting to enter the space port. People were beginning to get up to get their belongings together regardless of the space hostesses' attempts to keep everyone seated. Four days, John thought, and we are close to anarchy. He took his place in the queue for the exit, Sherlock coming in behind him.

They made their way down, the rickety stairs bringing some stark reality to the glamorous image of space travel that the company liked to portray in their brochures. It made John smile as he walked off towards the terminal. For the first time since this adventure began he felt light-hearted, he found himself looking forward to his new start. He gave a little hop to try out the gravity. Strangely enough, after four days on the ship Mars gravity didn't feel all that different. The Mars shoes with their heavy soles certainly helped as well.

He only realised that Sherlock wasn't following him when he heard the shouting. He turned around to see the tall figure of Sherlock in the distance, slowly pacing along the side of the space ship, pursued by a handful of security personnel who were trying to obstruct his progress. He swore under his breath and broke out of the line.

"Excuse me." John was trying to break through the security guards who were now encircling Sherlock. "Yes, excuse me." He managed to squeeze in. The guards were still walking along with Sherlock, who was ignoring them, continuing his slow walk along the ship's length.

"Sherlock," John hissed as he came alongside him. "What are you doing?"

Sherlock took no notice of him. The security guards were now beginning to hassle John as well.

"I'm sorry," John said, trying to look as pacifying as he could. "He's… ehm. He's my friend, and, ehm… you know. He's got some problems. He's not dangerous."

He was aware that he sounded like he was making it up on the spot, but he hoped that the security people would put it down to nerves. Unfortunately Sherlock, all big coat and imposing presence, didn't really look like he had any special needs. He had now made it all the way to the rear end of the ship, where he stopped abruptly. He suddenly focused on John, looking briefly surprised.

"John."

John turned immediately to the security personnel. "You see, he's snapped out of it. Let me take him back to customs. Come on, Sherlock." He tugged Sherlock's sleeve, making the most of the guards' obvious confusion to whisper to Sherlock. "I've told them you're special needs. Let's get out of here."

Sherlock twisted his face abruptly into a goofy smile and pointed at the craft. "John. John, it's a space ship."

The transformation was instantaneous, and very convincing. John managed a look that he hoped had the right amount of exasperation in it. "I know, Sherlock. We've been on it. Let's go and see the nice habitat." He pulled Sherlock's arm again.

With one last apologetic look to the security guards they began to make their way back to the line of passengers waiting to enter the colony. Sherlock still had a silly grin plastered on his face and was now looking around the space port building, doing a little pirouette every so often and clapping his hands in glee. The security guards followed closely behind, keeping a close eye on them and occasionally speaking into their radios.

John made a show of trying to calm Sherlock down, eventually giving him his phone for want of any better ideas. Sherlock instantly became all focus, and after half a minute John turned to the security personnel, trying to look reassuring. "He's fine now, he'll be fine until we get inside."

The group of guards looked unsure, but it was clear that they had other duties to attend to. Eventually they wandered off, looking back occasionally. John tried his best to avoid catching Sherlock's eye, although he could feel the taller man looking at him. When he thought it was safe he looked up.

Sherlock looked almost expressionless, but there was such a wicked glint in his eye that John couldn't suppress a giggle. In return Sherlock broke out into a wide grin followed by a deep, heartfelt laugh.

John blanched as he saw one of the security guards turn around to eye them suspiciously. He elbowed Sherlock urgently in the ribs. "Ssh, we can't giggle, they're still onto us." Sherlock resumed a look of gullible innocence and John gave the security guard a friendly wave. With that, the man obviously decided that they were both mad and walked off.

"What was that about?" John asked, taking his phone back. Sherlock looked thoughtful. "I was right about the ship. There's at least ten foot missing on the inside."

"That's a lot of space."

"Hm."

Outside the terminal building they walked along the broad, covered corridor and John looked down upon the crater that would be home from now on. It was a much larger place than he had at first thought, at least the size of a large city, and from what they could see from their transparent walkway it was bustling with activity.

In the elevator on the way down to the bottom of the crater he took out his phone and found the hostel booking. This was the one part he wasn't looking forward to – spending time in what was in essence a glorified box with a sink until he could establish himself as a GP again and rent something humane.

As they came out of the lift, John suddenly felt a bit awkward. He had no idea where Sherlock was staying and he realised he had no way of contacting him when they went their separate ways. Sherlock looked ready to pace off as soon as they were on the pavement. John cleared his throat.

"Right. Ehm. I'll be seeing you then."

"Yes," Sherlock said, distractedly, looking at the city. Then, suddenly, he seemed to register what John was saying and fixed him with a frown. "No. Come with me."

John hesitated. He felt out of his depth. There were so many things he was unsure about at this moment and Sherlock was only adding to them. "Sorry, Sherlock, I should really check in to my hotel first."

"Hostel. You are renting a two-by-three metre box on shadeside. I can't see why anyone would be in a hurry to go there."

John was getting embarrassed now. He didn't know how Sherlock had worked that out, but he'd hoped to keep quiet about it. "How did you figure that out?"

Sherlock looked at him as if he had said something daft. "You gave me your phone."

"Wha…? No, you weren't meant to go looking at everything. There's personal stuff on there."

"I know."

John looked incredulous. "Sherlock, I can't believe you went digging around my private correspondence while I was trying to keep you out of trouble. What were you thinking?"

Sherlock met his gaze with a look of complete innocence. "I was thinking it was quite interesting."

Before John could say anything, he cut in. "Look, I've got a two-bedroom suite booked at the Martian. It's one of the best hotels in the crater. It's up on the crater side, sunside, and I believe it has a pool, a gym and a cinema. You are welcome to join me. It's either that or live in a dark box. Your choice, Doctor."

With that, he strode off in the direction of the taxi ranks. John only hesitated for half a second. Cursing under his breath he went after Sherlock.