A/N: I'm actually amazed it took so long for me to write something in this 'verse, as a member of a theatre company called "Enterprise Entertainment". As usual with me, if enough people show interest (and possibly bribes) I can probably be convinced to expand this into a full-length story, eventually. For now, though, this was made necessary for me by the mind-palace scenes in series 3 and the melding scene from the Trek novel Vulcan! by Kathleen Sky - the idea that people can simply wander around inside each other's minds was just too much for me. As such, the plot of this story is less well-developed. Shh. It had been sitting there as just the mind-palace scenes for months, I thought I should just get it out there.

DISCLAIMER: Not only do I not own the Star Trek universe, I will not pretend to be an expert and I did not research anything about it while writing this story. It is incredibly likely that everything I claim about the workings of mind-melding and Vulcan culture is incorrect, and I am very sorry if that is the case. Also, a note on the canon: I'm putting this in the 2009 reboot!verse. As Vulcan was destroyed, the remaining Vulcans adopted a more positive attitude towards 'breeding' with humans, so it's no longer strange that Sherlock, born many years later, is half-human and half Vulcan.


The ridiculous thing was, the planet had looked so ordinary.

John had stood on the bridge and looked at the little lump of rock through the view screen just like everyone else, and he'd given a little sigh of boredom to himself. So many romantic tales of adventure and derring-do had drifted back to Earth from the logs of the USS Enterprise that John had thought exploratory missions would be anything but repetitive. Maybe the Enterprise had simply discovered all the exciting new worlds already.

But no - all they had found for months now were the corpses of celestial bodies technically classed as planets, but completely devoid of both life and interest.

Until this one.

He'd gone back down to his office and started up routine scans for life on the surface, and that was where the oddities had started. His scanners had seemed unable to decide whether there was life on the planet or not: though respiration was apparently absent, the levels of psychic activity were high and some of the machines were adamant that they could detect heartbeats.

So John had contacted the bridge, and the Captain had put her First Officer in command of a landing party.

John had irrational responses to a lot of his Captain's decisions with regard to her FO. When she put him in command of the landing parties, he resented her for putting him in danger she was unwilling to face herself: when she did choose to lead the parties herself, he resented her for keeping the xenobiologist so close to her, as though she were afraid to leave the USS Adventure in his command. Most of all, it was the tiny knowing smiles she gave John every time she ordered either of them to do anything.

The rest of the crew, when assigned to a landing party led by Sherlock Holmes, let out a special kind of collective groan that made John smile.

The half-Vulcan xenobiologist was generally disliked by the rest of the crew, and it wasn't difficult to understand why; Sherlock had a rather abrupt manner and didn't much care whom he upset in his command. There was a rumour going around that he had only been promoted to FO because he knew something about their supervising Admiral, in that way that he had of knowing your darkest secrets and 'accidentally' spilling them in front of your Commanding Officer.

Very few people voiced their dislike in places where it might drift back to him.

For some reason, and John could never quite fathom what it was, Sherlock Holmes seemed to like him. They had met at the Academy: the class they were taking together was John's favourite, and so perhaps he had impressed the Vulcan by "not being quite as stupid as everyone else in the class", which, coming from Sherlock, was a compliment indeed.

Usually, Sherlock was just as reluctant to lead landing parties as the rest of the crew was to follow him: on this particular occasion, however, he had glanced at John's monitors and let out a noise of interest. "Fascinating," he had breathed. "The planet shows no signs of respiration or heat, but extremely high levels of psychic activity. I will need psi-able crew members in my landing party," he directed at the comm link with the bridge.

Captain Adler hummed. "You can take T'Penya," she negotiated. "But you need psi-null crew members as well. And you can't take Doctor Watson," she pre-empted; Sherlock closed his mouth with a frown. He always looked surprised when the Captain seemed to know what he was about to say before he said it: John had tried to explain to him once that it was because Sherlock requested John's assistance on every landing party that he commanded.

T'Penya was a young Vulcan woman who alternated her shifts between the medical bay and the xenobiology lab; when she had been enlisted to the Adventure she had been more or less fresh from the Academy, and though her knowledge on Vulcan medicine was excellent, John found he often had to give her direction in other fields. If Sherlock's expression at the command was anything to go by, she displayed a similar inexperienced enthusiasm in his laboratory. "Very well," the Vulcan had said reluctantly, and after John had wished him luck that had appeared to have been that.

The landing party had been on the planet's surface for less than twenty minutes when John's comm crackled back into life. "Doctor Watson," Captain Adler's voice barked. "Something's gone wrong with the landing party. We're a crew-member down and Holmes is compromised. We're beaming them up now, prepare to receive the First Officer for urgent medical attention."

Worry immediately spiked through John's stomach. "What happened? What's wrong with him?"

"I'm not sure yet," Adler replied. Though she sounded as in-control as she always did, John could detect a note of concern in her lilting voice. "It didn't sound good, I requested they beam up before they explained further. I'm coming down to hear T'Penya's report from medical."

John's second-in-command cleared her throat from behind. "Lestrade's hailing us," she told him, nerves making her stutter slightly. "What's going on? Sherlock was on that landing party, wasn't he?"

Molly Hooper had always had a bit of a hopeless crush on the First Officer: hopeless because Sherlock knew about it and had never once acknowledged it beyond the occasional winning smile when he asked her to do something. John knew that it wasn't Vulcan to entertain ideas of romance, but he wasn't sure that Sherlock was a sexual being at all; he'd never asked, quite naturally, and although being the Chief Medical Officer meant he knew that the First Officer possessed working and surprisingly human sexual organs, it was entirely possible that he hadn't inherited any kind of libido to go along with them.

Not that John spent a lot of time theorising about his First Officer and best friend's sexual organs and practices. Curiosity was human, that was all.

"Sherlock's been hurt somehow," he told her. "Take Doctor Stamford down to the transporter bay to bring him back here, would you? The Captain said she's taking their report here. Apparently we lost another crew member too."

Molly's face fell. It had been months since they had last lost a crew member on a landing expedition. "Very good, sir," she said softly instead, and turned to leave.

John had been preparing himself for the worst, but the landing party burst into the medical bay supporting an unconscious Sherlock between them; he didn't appear to be wounded, but his face as they lowered him onto the nearest bed was ashen, even his lush lips turning white. "What happened?" John asked T'Penya briskly, bending over his friend with a tricorder and activating the bed's vital stat monitor. His heartbeat was wild and uneven, his temperature far higher than his recorded baseline.

"I'm not entirely sure," the Vulcan answered him, her voice shrill with panic. "There were things down there, but I don't think they were alive - they were more like ghosts. They were psi-able, I could feel them probing at my mind. I think that's how Ensign Phillamore died: I could stop them getting into my mind, but he wouldn't have been able to. The Commander… he said he would try to communicate with them, that if they were psi-able he could make them see that we weren't a threat, because they were so hostile. But then he didn't react when Ensign Phillamore collapsed, and then I checked his pulse and realised he was dead - and…" she stuttered, tears rising to her bright emerald-green eyes. Captain Adler rubbed her arm comfortingly to coax the rest of the story from her. "And then I turned around to tell Commander Holmes and he'd collapsed too, and he was sort of thrashing around like he was trying to fight them off, and I thought - if he couldn't stop them, it killed Ensign Phillamore so quickly - the rest of the psi-null party were in danger, so I contacted the bridge to get us out of there."

The Captain frowned. "And you'd never seen or felt anything like them before?" she asked slowly.

T'Penya shook her head, tears leaking from her eyes. "They were like shadows, humanoid shadows," she said. "I could feel them pressing into my mind from the moment I saw them. Shutting them out was an automatic response."

John frowned at his tricorder. "He's conscious," he said, trying not to panic. "But he's completely non-responsive. It's like his mind has just shut down."

"It's a sort of last-ditch defence," T'Penya told him, bending over her commanding officer and flashing her pen-light in his eyes. "He will have retreated into his mind to shut them out from the inside - if he doesn't get out, then they can't get in."

The young Vulcan straightened up and looked at John uncertainly. "I… I could know more about how we can help him if I could get into his mind," she suggested hesitantly. "I mean, if I melded with him."

"It's too dangerous," John insisted immediately. "Whatever's in there, it's already killed one person. If you go into Sherlock's mind you'll be a target."

T'Penya shook her head, growing bolder. "I could hold them off before," she protested. "And in Commander Holmes' mind they won't be focussing on me anyway."

John watched her for a moment. It was against everything he'd ever believed to let a younger crew member risk her life for a chance at diagnosing someone else - but this was Sherlock, and if T'Penya didn't risk her life he could die. "Captain?" he deferred, passing the decision onto someone whose best friend wasn't on the line.

Captain Adler gave the two of them a long look. "She says she can do it," she said finally. "The decision's with you, Doctor Watson."

He looked at T'Penya. "It has to be up to you," he said. "I don't like to put you in danger, but if you're certain that you'll be safe… if you agree to withdraw the moment you feel at risk."

The Vulcan hesitated for a moment, her eyes darting down to the First Officer. "I can do it," she said firmly.

"Okay then," John replied, stepping back and sharing a slightly apprehensive look with the Captain. T'Penya stepped forward and placed her fingers on Sherlock's melding points, closing her eyes in concentration.

For a long moment she stood like that, while John tried not to hold his breath in anticipation, unsure what to expect. Then, just as he began to get nervous, the young alien let out her breath in a huff and opened her eyes. "He won't let me in," she said quietly, looking up at John in defeat. "I tried everything I know - he's shut his mind so tightly to them that he won't let me in either."

John looked at the Captain again; she shook her head slightly. "Is there anything else you can try?" she asked T'Penya. "I'm not leaving my FO like this."

"I don't know," the younger woman said, twisting her hands in agitation. "I think if we… that planet's atmosphere was made up differently to this ship, and since the others let us go once we beamed up here, I don't think they can breathe in our air. If we could get them out of his mind they'd die before they could attack anyone else. I suppose we have to hope he can get rid of them on his own."

They stood in silence for a moment, desperately looking at each other. Molly Hooper had listened in from where she was checking up on the other members of the landing party; her dark eyes were wide with fear as she looked desperately at John. Then Captain Adler cleared her throat. "Doctor Watson," she said softly. "I don't like to ask, but… you could try."

John blinked at her. "Try what?" he asked.

She gestured at Sherlock. "Getting into Commander Holmes' mind," she expanded. "T'Penya could assist you with the meld, and it's probable that he will be more receptive to your presence than he was to hers, since the two of you are friends."

"Meld with Sherlock?" John repeated, looking at him. He'd never considered that before. He knew that psi-null beings could learn to initiate melds with psi-able beings, but it had always been an abstract concept, something that other people did and he could never really understand why - surely it would be easier just to continue doing it the other way around. He looked at T'Penya. "Could you do that?" he asked her.

She looked uncertain. "I think so," she said. "I can facilitate your mind to reach out to his, but… he has to be aware enough to know you're trying before he can let you in even if he wants to."

"It's worth a try," John insisted, shaking out his arms as though preparing for heavy lifting.

T'Penya glanced at Captain Adler for confirmation. "All right," she said, sounding apprehensive. "Put your hands here, like this."

She guided his fingers into the correct positions, then placed one of her own hands over his and the other to his temple, connecting them both to her. "Okay," she said quietly. "Close your eyes and reach out with your mind. Imagine your mind leaking out of your fingers and into his head. I'm here, I'll help you."

For a moment, John just stood there with his eyes shut and his hands on Sherlock's face, trying to do as T'Penya said but feeling incredibly stupid. Then something seemed to shift, like he'd lost his balance, and he was falling; he opened his eyes as an automatic reflex to stop himself hitting the ground, and -

He was standing in a field of dry grass, under a pale sky streaked with cloud.

A few steps to his right was a gravel path edged with some kind of pale stone; a garden path, leading up the slight rise where he stood to the enormous stone castle in front of him.

John tried to think of other words for it, other descriptions, but it seemed to come straight out of an old Earth history book depicting the Medieval Age, a towering structure of grey brick extending impossibly far up, ringed in a high wall and apparently deserted. The only thing it lacked was a moat and a drawbridge. In fact, John searched for any kind of door at all in vain. A few crows circled an upper turret, cawing morosely. A breeze ruffled his hair and bent the blades of grass until they tickled his ankles. Besides the castle, the horizon was unbroken, bleak.

It was not at all what he had expected to find here - not that he understood exactly where here was. Was he inside Sherlock's mind, now? Was this his image he was seeing now - a human representation of the Vulcan's consciousness, his own mind attempting to make sense of what was actually here - or Sherlock's own image, the way he wanted to see himself?

Mind-palace, Sherlock had always called it. He'd still expected something a little brighter, more practical, less… morbidly romantic.

And something a little more under siege, he reminded himself, checking the horizon once more. The sky was calm and largely blue, the grass dry but not dead, the air quiet but for the melancholy cries of the circling crows. Perhaps whatever was wrong was confined to that one tower.

There was a noise behind him, a rush of wind, a crackling of gravel. John whirled around, expecting to see Sherlock frowning at him, preparing to shout and rage at this invasion of privacy. Instead, John's jaw dropped.

Behind him, out of his sight, a wall of shadow was advancing on the castle, roiling and charging with a low whoosh of displaced air. As John watched, frozen in shock, the sky above him darkened to black, though that above the castle itself remained calm.

And then John realised that Sherlock hadn't let him into his mind. That Sherlock's consciousness was holed up inside that fortress, cowering while the walls held the darkness at bay. That he, a psi-null being, had little chance against them, undefended out here.

John turned and ran for the castle walls.

Even where the gravel path met the stone wall of the castle, there was no door, but John understood that now. Sherlock had tried to make the place he was hiding in as impregnable as possible. Perhaps T'Penya had even made it as far as he had before withdrawing, unable to find entry. Had she known the danger she was sending John into? Sherlock letting him into his mind-palace was possibly John's only hope - and maybe even Sherlock's, as well.

He banged his fists on the stone, even though he knew that they would make no sound. "Sherlock!" he called. "Sherlock, it's me! You need to let me in!"

Something in the air rippled hesitantly, clouds gathering together above him like frown-lines. "Sherlock, please," he shouted, louder in case the Vulcan simply hadn't heard him properly. "It's John, trust me, I'm here to help you!"

The stone shifted under his fingertips as though pulling away from his touch. John's heart sank; was this Sherlock withdrawing from him, shaking him off, shutting him out?

But after a moment, the shifting stones resolved themselves into a doorhandle, cut with a fine line into the wall. John breathed out in such relief he felt light-headed. "Thank you," he muttered, not sure if he was saying it for his own benefit or just in case Sherlock could hear him.

The shadows were still advancing, seeming to converge on him as though sensing weakness, and so John took a deep breath in and opened the door, stumbling into the courtyard of Sherlock's mind. He slammed the door shut behind him as quickly as he could against the rushing wave of darkness, breathing heavily as the stone melded back into solid wall under the weight of his forehead as he leaned against it.

Once he had caught his breath, John stood up and looked around.

The courtyard was bare, grey stone on all sides. He had expected something of the world to become less real, more the slightly distorted fairytale of his own dreams, but Sherlock's mind was crystal-clear and sharp on the eye, distressingly accurate down to the lichen growing between the cobblestones on the ground. Of course it is, he reasoned to himself. It was Sherlock's mind.

The door to the castle proper stood opposite him, and since the courtyard was achingly empty, John made for it. He knocked out of some kind of sense of politeness, but the door swung open even as his knuckles touched it, inviting him into the cavernous corridor beyond.

For the first few steps it was quiet, the sound of John's Starfleet-regulation shoes ringing loud across the stone, but as he ventured deeper into the hall sounds began to creep out of the walls: voices, a child crying, the ticking of a grandfather clock, a dog barking, the whooshing sound that John recognised as the Adventure at warp factor one. John followed the voices when he reached the end of the corridor and had to choose a direction, calling out for Sherlock as he went.

The Science Officer apparently wasn't going to make himself easy to find in this palace, though, and John wandered for a while, peering into the loudest rooms as he went and raising incredulous eyebrows at some of the oddities therein. One room contained what looked like a giant sphere hollowed into the ground, luminous fish from odd planets swimming around it as a cool female voice intoned academic questions at the empty air. John thought he remembered hearing about Vulcan test simulators in a lecture at the Academy. Another housed a curly-haired Vulcan boy sitting dejectedly on a bench with an older man that John instantly recognised as a young Sherlock with his godfather, Ambassador Spock.

"I know you feel as though your teachers cannot understand how you are feeling," the older alien was saying, rubbing soothing circles on his younger counterpart's back.

Sherlock sniffed. "How can they? They're not even genetically the same species as I am."

Spock made a soothing noise. "I thought the same when I was smaller. My father did not help - the other children would say awful things about my parents, and my father would never deny them. It was not until I melded with a full Vulcan that I realised the species was capable of emotions at all, and not until my father admitted to having them that I realised the truth."

"What truth?" the little boy asked, apparently spellbound by his elder's reminiscence.

The Ambassador looked down at his godson and smiled softly. "Vulcans feel even more deeply and acutely than humans do. Raw emotions the way that a Vulcan feels them can destroy a person - they become too much to bear without collapsing underneath their weight. So Vulcans learn on their own at a very early age to control them, to lock them away, to fear them so much that they will never let more than the smallest glimmer of emotion into the front of their minds. That is why we must endure Pon Farr - the struggle to hold everything back becomes too much."

Sherlock stared as though he didn't believe him. "That's why they always look at me like I'm something disgusting? Because they're scared of emotions?"

Spock gave the tiniest resigned shrug of his shoulders. "We cannot possibly understand the way in which true Vulcans rationalise the emotions of others. All I know is that for a fully Vulcan child to display as much emotion as you do would be dangerous to his mind, and it will take some time for the schoolmasters to adjust to the fact that half-human children do not learn the control that Vulcan children do on their own."

"What did you do?" Sherlock asked, twisting his already pale hands between his knees nervously.

The older Vulcan sighed. "I learned to control my emotions in order to fit in with my peers. It was not until I left Vulcan and joined Starfleet that I socialised with humans at all, and not until I met one particular human that I began to let myself feel emotions again, seeing how his feelings benefited him."

"Captain Kirk," Sherlock said proudly, looking up at his godfather with wide eyes.

Spock smiled indulgently. "Yes, Captain Kirk." His hand finally stopped its soothing motions on the boy's back as the older Vulcan frowned. "Control of your emotions is a valuable skill, Sherlock, particularly whilst you live among Vulcans. But there are times when you ought to allow your emotions to lead you, and friendships are one of them. My friendship with Jim remains the brightest part of my life, and if I had not allowed myself to have it, I would not be where I am today."

The little boy creased his forehead into a mighty frown. "But how do I tell who I can have friendships with?"

The Ambassador smiled, pulling his godson closer against his side in an approximation of a hug. "Trust me, Sherlock," he said warmly, "you will know."

His dark, piercing eyes left the boy, then, and travelled directly upwards to the doorway. John froze, expecting the Vulcan to shout in angry surprise at his presence, but if the alien even registered that he was there, he did not react. Shaken - and slightly guilty that he had lingered to watch such a private moment - John moved on.

At the end of this particular corridor was a spiral staircase winding slowly upwards, and a corresponding hole in the flagstone floor where it descended. John stared downwards; something underground down that staircase was clanking ominously, like the chains in Old Earth dungeons, and he thought he could hear the faint strains of high-pitched, maniacal laughter. For a moment he thought about going down there, to see what Sherlock kept in the dungeons of his mind, but he knew that there was no way the Vulcan was hiding in there to keep himself safe, so he made himself climb upwards instead.

There were more windows on the next level, and plush rugs in rich reds stretching over the floor and squishing pleasantly under John's shoes. A few of the doors along the corridor stood open, revealing bookshelves and science laboratories and what looked like a medical exam room.

By the time he had ascertained that the Vulcan wasn't hiding on this floor, John had an entirely new appreciation for his friend's incredible mind. There was simply so much here - and not only factual information, but memories and hopes and dreams. Sentiment leaked from every room, even the ones clearly designed for the recollection of facts. Much of it was a dark, often frightening sentiment - the shadowy office that seemed to stretch on forever in particular John had shied away from - but they were personal thoughts and memories, all of it so completely Sherlock that even the most threatening rooms made John smile.

The corridor ended in an ostentatious pair of mahogany doors; John pushed them open as slowly as he could, trying to be unobtrusive, but the door creaked deafeningly as he eased it open, making him wince and prepare to apologise to who - or what - ever was in the room beyond.

An enormous, gloomily-lit courtroom greeted him, furnished in sickly green and deep red and rich wood. To John's surprise, it was almost empty; a tall, thin figure loomed from the judge's stand and a solitary man sat in the red leather stands, head bowed. John recognised the judge apparent as Sherlock's older half-brother, Mycroft; facing away, it took him longer to identify the lone audience as himself.

It came as a bit of a shock, though he supposed he had to be in this castle somewhere. He knew he was a significant part of Sherlock's life, surely he must take up residence in his mind, if he made space for some of the other things that John had seen so far on his wander. Neither of the room's occupants seemed to have noticed him, so John watched for a while as Mycroft sat in the judge's seat and stared disapprovingly down at him. Perhaps it was meant to represent the fact that Sherlock's relationship with John was not particularly Vulcan; he had seen that very same look on Mycroft's pinched face the one time they had met in person. He hoped that this wasn't the only representation of him in here, that the shame Mycroft made him feel about their relationship wasn't Sherlock's dominant view of it. It was interesting that the older, full-blooded Vulcan held a position of such power in Sherlock's mind.

But his friend was clearly not in this room, and John had not invaded his mind like this to judge or psychoanalyse it, so he closed the door as quietly as he had opened it and moved on.

The next flight of spiral stairs was made of wood, and the floor above seemed to shine as though the walls were made of glass, but when John stepped off the staircase it was evident that the corridors were simply well-lit by the same sensor lights that Starfleet employed. He grinned at their familiarity.

The barking dog was louder here, but so were several of the voices; John hoped that the light everywhere signified that he had left the nightmarish memories behind. The first door that he opened swung inwards onto one of the tiny rooms the cadets of Starfleet Academy were provided, with a younger Sherlock cross-legged on the bed reading a textbook at lightning speed.

A thunderous crash rocked the room before John had time to process what was inside it; he cried out as he was thrown against the wall, almost touching the occupant of the bed. The young Sherlock didn't move, apparently noticing neither the crash nor the grown Starfleet Officer who had almost fallen on top of him.

John stood up carefully, holding onto the wall against the aftershocks of the crash: assuming the young Sherlock could neither see nor hear him, he rushed to the room's window and looked out.

The shadows had collected around the outer wall of the castle, swarming and shifting, clearly looking for a way in. John suppressed a shudder and turned back to the Sherlock on the bed, who still hadn't moved.

No-one that John had run into so far had noticed him, he realised; opening that door would definitely have caused even someone far less observant than Sherlock to look up. Perhaps these memory-versions of Sherlock were somehow different from him because they weren't real, just like holograms being played back for the real Sherlock's amusement. He supposed that would make it easier for him to recognise the real Sherlock when he found him. Or would that Sherlock not notice him either? What would he do if he never found a Sherlock who would listen to him?

He backed out of the bedroom quickly, closing the door behind him and leaning against it, breathing deeply to try to calm himself down. T'Penya would not have sent him into Sherlock's mind if he could not communicate with the Vulcan from within it. He just needed to find the place that Sherlock would have hidden himself to keep safe, and talk him into fighting off the shadows that were marching on the castle walls.

The next room was a lecture theatre that John recognised from Starfleet Academy, empty but for the furniture. The blackboard was covered in a detailed diagram of what looked like the Adventure's engine bay, although John couldn't tell for sure. He was a doctor, not an engineer, he thought with a smile.

He moved through the rooms faster now, barely opening the door before ascertaining that none of its occupants were the Sherlock that John knew. He paused, though, when one door opened onto a science laboratory at the Academy that John would never forget.

That was his own face, barely twenty years old, sitting opposite a shock of dark curls and grinning broadly. John couldn't help but wander closer to hear the well-remembered conversation.

"John Watson, human and xeno-medicine," the younger him was saying, holding out a broad hand.

Sherlock's back was to him, but John could see the eye-roll anyway. "Obviously. You want to be a doctor. Your father wanted you to join the Earth army, but your sense of adventure and your mother's fears for your safety caused you to enlist in Starfleet and take medical courses instead. You're carrying a copy of Enterprise: Exploratory Missions at the Edge of Space, clearly for light reading and not for study. You fancy yourself a real Leonard McCoy, don't you, John Watson?" he said scathingly.

John beamed, unconcerned. "Yes, I do," he said brightly. Doctor McCoy of the USS Enterprise had always been his hero. "That was… brilliant. I don't think I could have summed myself up that succinctly."

Sherlock had smiled shyly and finally taken the hand that John had held out for him. "Sherlock Holmes," he introduced. "Experimental xenobiology. I'm also familiar with the logs of the USS Enterprise, though I studied them in slightly less sensational form."

His heart squeezed fondly at the deja-vu of the memory, but John backed away from it nonetheless and shut the door behind him. It was unbelievably touching that Sherlock kept that memory preserved like this.

The door beside it stopped him dead.

John didn't recognise the room within, ostentatiously furnished, dominated by the magnificent canopied four-poster against one wall. He only looked at the décor for a moment, though, before his attention was caught by the room's two occupants.

Sherlock was on his back on the four-poster, stark naked, pale skin flushed green. And kneeling over him, just as naked, hands roving hungrily over the bare skin in front of him, was John himself.

His jaw fell open as he watched himself bend to kiss the Vulcan Science Officer; for a moment, his entire world threatened to tip over and leave him on the ground, but John quickly rationalised the scene in front of him.

He'd thought about it, too. Of course he had, his best friend looking like he did - it wasn't like there were a lot of opportunities to release that kind of tension on a five-year assignment with the same crew. He'd be a fool to pretend he hadn't caught himself fantasising about Sherlock's lips or his long-fingered hands or his unnaturally perfect curls, and realistically, if John were to build his own castle for the wanderings of his mind there might be a room just like this one in it, though perhaps with a stronger lock on the door.

He forced himself to look up again, to watch himself sit back on his heels over the Vulcan's belly and take one of Sherlock's hands in his own, pressing his lips against the pads of his fingers. No doubt Sherlock had noticed John's fascination with his hands, with the culture surrounding the anatomical sensitivity of Vulcan fingers, because this John that he had imagined was running his lips carefully over Sherlock's fingers, then his tongue, then sliding the index finger between his teeth and hollowing his cheeks while the Science Officer lay stock still and wide-eyed underneath him.

In the silence of the room, the tiny whimper accompanying John's exhale was painfully obvious, but neither of the occupants on the bed seemed to notice. Not the real Sherlock, then. John probably ought to leave - Sherlock's sexual fantasies were private, after all, perhaps more so than most of the other rooms John had explored so far.

Except that he couldn't leave. He seemed to be stuck there watching just as surely as if his feet had become glued to the plush carpet.

They made a stunning picture together. John had never imagined it from this angle before, always picturing his own perspective - and, now he thought of it, always in a series of impressions rather than a solid image like this one. He'd always felt so guilty using Sherlock like this, even in his mind, that he'd only imagined parts of a whole: the sensation of cupid's-bowed lips against his own, long and confident fingers wrapped around his cock, the steadying hum of his friend's smooth baritone voice. He supposed Sherlock's mind wouldn't allow such imprecise imaginings even if the whole picture did make him feel guilty.

There was no guilt to the scene, though; perhaps it didn't bother him so much. As he watched, John carefully put Sherlock's fingers aside in favour of joining their lips, careful presses of half-open mouths so that John could almost see their breath mingling between them. Gently, he slid down the Vulcan's body until he fit neatly between his legs, falling to his elbows and pressing their bodies together. The pale green of Sherlock's blush sat nicely against John's tanned skin as they moved together, their respective genitalia concealed from John's view but clearly aligned in delightful ways from the shudders rocking both of their bodies. Sherlock's long fingers clutched at John's back as they moved, his head thrown back and gasping for breath.

John leaned against the doorway before he lost his balance, echoes of sensation ghosting across his body. He watched himself lick up the ridge of Sherlock's collarbone, feeling the heat and softness of his friend's skin against his real lips and tongue, suppressing the suddenly overwhelming desire to go over there and find out what Sherlock would taste like. Any chance he might have ever had of shifting his fantasies onto a more appropriate target was diminishing before his eyes: if there was the tiniest possibility that he and Sherlock could have what was in front of him now, how could he ever want anything else?

Something in his stomach clenched as Sherlock's fingers rooted in his hair, joining their lips together once more. This Sherlock was so desperate, as though he needed John to breathe. He'd never imagined that the half-Vulcan officer would want him so passionately: when he had allowed himself to imagine it he'd always thought that Sherlock would be slow and controlled like he was in everything else, almost unbearably teasing and sensual.

But this was Sherlock's mind, Sherlock's fantasy, Sherlock's thoughts on what he would be like if he and John ever got into this kind of situation. This Sherlock, who tangled tongues so fervently with John, one hand sliding from the sweat pooling in the small of John's back down between them to their groins - this was how it would be, this was real.

The John on the bed pushed himself up into one elbow, revealing the places where they were joined to the doorway. He'd seen his friend's genitals before, but never like this: his cock swollen with blood and anticipation, leaping into his hand when he affixed it around the two of them, coaxing a moan from both of the Johns in the room.

The one in the doorway clamped a hand over his mouth, even though he knew no-one else could hear him. Sherlock's back arched as he began to stroke them, even the throbbing of their arousals in perfect synchronisation.

He ached to go over there, and wondered what would happen if he did: would he be able to touch them, or would his hand slide through Sherlock's flushed skin like a hologram? Surely the real Sherlock would be able to interact with his fantasies, to take his own place in this one? Could John do that? Sherlock would know, if John ever found him in this castle; he would take one look at John and see the flush on his cheeks and the rumples in his uniform and he would know.

But would that be a bad thing?

The bed's occupants grew more and more desperate as he watched, hands gripping and caressing, John's lips travelling across the pulse points on Sherlock's neck, the half-Vulcan's body straining as his thighs wrapped around John's hips. The John in the doorway pressed the heel of his hand into his crotch and tried not to move closer as his friend's hips began to falter, his breath stuttering out of his throat. It couldn't have been more obvious that he was close, and John had to forcibly pull his hand away from his groin before he lost control.

Sherlock's gasps gave way to helpless pants as he writhed under the hologram-John's hands and lips, the latter having given up on his own pleasure for the moment to focus on the First Officer's, trailing kisses down his stomach and finally pressing a chaste peck of his lips onto the tip of Sherlock's erection, making him shudder.

The John in the doorway licked his lips involuntarily, his hands squeezing the door-frame until it hurt. He'd imagined this so many times he could almost feel the weight of his friend's cock in his mouth, his hips bucking under his hands, his long fingers sliding into his hair. He closed his eyes and turned away, unable to bear the sight that went with Sherlock's ragged cry of John!.

He stayed that way until the noise subsided, holding on through the desperate arousal at the knowledge that Sherlock was coming not ten feet from where he stood and he couldn't do anything but watch. When he did open his eyes, it was to the sight of himself crawling back into Sherlock's arms, pressing their smiles together as the Vulcan's hand slid down his stomach -

John sighed and turned away, adjusting his trousers as he tried to calm himself down. He had to find Sherlock before he could decide how they could handle this.

The next spiral staircase led onto the bridge of the Adventure; Sherlock himself was conspicuously absent, and Captain Adler didn't spare John a glance from the empty view screen as he wandered through. The rest of the level seemed to be an amalgam of rooms from the ship, including John's office and med bay, the science laboratories and the engine room, where John was startled and slightly disturbed to find two of Lestrade's senior engineers, Anderson and Donovan, locked in an apparently passionate embrace. Like everyone else in Sherlock's mind, the two appeared not to even register John's presence in the room as he hurriedly ducked back out. He'd known there was something between those two, but he hadn't known it was that. Of course Sherlock had guessed it.

The FO himself, though, continued to be noticeable only by his absence. John was beginning to despair a little. He had to be in here somewhere, didn't he? This was his mind.

Another crash rocked him, throwing him against one wall. John's heart pounded in time with the constant shudders of the floor, not subsiding this time but continuing to make finding his feet difficult.

The dog barked again, apparently coming from above them. John blinked.

The tower.

The last staircase from the bridge – John spared a thought for why the Vulcan had to have so many stairs in his mind - was walled with brick, and ended with a solid-looking wooden door. John took a deep breath before he pushed it noisily open.

Sherlock's head turned slowly to look at him from where he sat, curled against the far wall and staring morosely out of the low window. "John," he said softly.

A rush of relief hit him at around the same moment as the dog; a hairy, reddish animal that barked happily and planted its front paws into John's chest, its tongue aiming for his face. He laughed from the sheer relief of it, gently removing the dog from his chest and grinning at his best friend. Sherlock didn't return the expression.

"Redbeard, here," he called the dog without emotion. John started slightly: Sherlock's override passcode to his quarters was 'Redbeard'. He'd always assumed it was a tip of the hat to an Old Earth pirate.

Redbeard lolloped happily back to him, settling down on Sherlock's outstretched legs with a flump. John walked over to him, allowing the heavy door to close behind him, leaning against the wall to protect himself from the rocking of the floor. "Sherlock," he said quietly. "How are you doing?"

The First Officer looked him critically up and down. "You saw everything," he concluded, ignoring John's question.

"Almost everything," John admitted, sitting down on the stone floor beside him. "I'm really sorry, Sherlock, but I had to. Your body is struggling, you can't stay here like this. I had to find you."

Sherlock's hands stroked absently through Redbeard's fur as though he was using it to keep himself steady. The dog's tail thumped heavily against the floor. "I can't go out there," he said dully. "You saw them. I know my body's going into shock, that's why I came here."

"They didn't follow the rest of the crew when they beamed back," John told him. "We don't think they can survive in the ship's air. If you can just force them out of your mind, they'll die."

Sherlock eyed him, still completely emotionless. "You're surprisingly calm for someone who's seen the things you've just seen," he commented. "Most people would be slightly unnerved to find out that their best friend thinks about performing sexual acts with them."

John couldn't stop himself from freezing for a moment before he forced himself to relax and look unconcerned. "It doesn't unnerve me," he said truthfully. "We spend so much time together it would probably be stranger if you didn't think about it. God knows I do."

He realised what he'd said a moment after it escaped his lips and bit them rather savagely in retaliation. He probably hadn't needed to sound so emphatic. Sherlock stared at him intently. "Sherlock, you're my best friend," John told him. "I care about you more than anyone else in the world. I think that can survive me seeing your sexual fantasies."

The science officer turned away, resting his head against the wall behind him. "You didn't stay until the end," he stated quietly.

John frowned. "It wasn't something I felt like I should be watching," he said. "And I wanted to find you and get you back more than I wanted to see how you thought sex between us would end." Sherlock smiled bitterly. "Why, how did it end?" he asked, grinning.

The FO sighed. "It doesn't matter," he lied. It was almost amusing how he always seemed to think he was convincing when he did that.

"Okay," John said. "Let's concentrate on getting rid of these shadowy things, and then I can get out of your mind."

Sherlock stood up, dislodging Redbeard from his lap with a sharp bark, and started to pace. "Those things take out your body through your mind," he said quickly. "Mine has gone into shock from the effort of keeping them out, but the ensign who died - Phillamore, I believe - it must have gone straight to his medulla and stopped his heart. But if I stabilise my body to combat the shock, it should expel them. That's why I locked myself in here."

Trusting Sherlock to know his own body, John nodded. His friend dropped one hand to fondle his dog's ears. "Spock gave him to me when I was six," he explained, smiling fondly at the animal. "A living thing that I could show my emotions to, so that I didn't have to show them to the other children. I thought I could calm myself down with him. It worked for a while."

"Did you know I was here?" John asked. "I mean, you let me in, I thought you'd come looking for me. But then I had to look through the whole castle to find you here."

Sherlock shook his head. "I think letting you in is an automatic reaction now," he said, smiling softly. John grinned. "I just gradually became aware that you were in my mind. I figured you would find me in the end."

John frowned. "But you let me look at everything," he pressed. "If you'd come to find me I might not have looked in that room at all."

"I don't think there's anything in this palace I could have kept from you forever," the xenobiologist said softly. "I suppose a part of me wanted you to see that room."

There was a pause while John worked through the statement. If Sherlock wanted John to know that he thought about… that, if their mutual attraction was out in the open, they would almost have to do something about it. Did Sherlock want him to do something about it? Could they do that without ruining the relationship that they would have to maintain for the rest of their five-year mission?

Sherlock was still watching him with an intense expression: John took a deep breath and met his eyes. "Sherlock, I…"

His friend waved a hand to cut him off. "Come with me," he said instead, holding out the hand to help John to his feet and sweeping towards the door.

The dog bounded happily alongside them as they descended the spiral staircases, ignoring the Adventure's bridge to continue to the level below. "Do you actually know for certain that Anderson and Donovan are sleeping together?" John asked as they passed the bridge, grinning. "Or was that just your mind speculating?"

The science officer snorted derisively. "I don't know how you can see them together and not know for certain," he said. John laughed.

He had a slight suspicion as to where they might be heading, but he was still a little surprised when Sherlock spun himself to a stop in front of the room that John had had to drag himself away from. His breath caught a little from the memories of what had been inside it, and anticipation of why his friend might be bringing him back here. Sherlock turned to him and took a shaky breath in.

"This is how it ends," he said quietly, and pushed the door open.

The two of them were still on the bed, still tangled up in each other's naked forms, skin now slicked with the particular sheen of cooling sweat. John watched as they kissed languidly, hands roaming with reverential fondness.

A sort of lump rose in his throat. He didn't think that he could have sex with someone he cared about as much as Sherlock without some kind of sentiment being involved, but surely this was more than no-strings-attached physical closeness.

Then the John on the bed broke away from their kisses to place one final press of lips onto the Vulcan's forehead, holding him close and stroking tender fingers through his thick curls. The John in the doorway swallowed.

"This isn't a sex fantasy," he stated softly, not looking at Sherlock.

The FO shifted beside him. "It never was," he admitted, sounding nervous again.

John watched them for a moment longer. Could they have that on the Adventure? Captain Adler probably wouldn't like it, though that was almost a point in its favour from John's perspective. He looked up at the science officer, who was staring fixedly at the bed as though trying not to see it. "Okay," he said finally, meeting his friend's eyes firmly.

"Okay what?" Sherlock asked bewilderedly.

"What do you want?" John asked him. He would have died for the taller man hours after they had first met: perhaps that ought to have been his first clue. Thinking about having this kind of intimacy with him was like lifting a floodgate in his mind, allowing himself to consider something he'd always shut out of his thoughts before it could take conscious hold.

Sherlock stared at him. Then he looked back at the bed; John had picked up his PAD-D and was looking at what appeared to be the med-bay duty roster, one arm still looped around Sherlock's back as the FO dozed against his chest. The John in the doorway smiled. "Okay," he repeated. He reached out with one hand and folded it around Sherlock's long fingers. "I want that too."

The crash this time was almost deafening, and John thought he heard the sound of wood cracking and splintering from far away. He looked up at Sherlock in horror, but the Vulcan was still staring at him as though frozen as their world shook around them. "John," he whispered after a moment, his fingers clamping down on John's hand.

And then they were kissing, and it was brilliant: Sherlock's lips pulled and sucked at his own with the scientist's usual determination, their fingers clutching at each other to keep themselves upright as the floor shook around them.

"Are you sure?" Sherlock asked when he finally pulled away. John cupped his cheek with one hand, slightly startled at the serious look in his grey-green eyes. "John, can you promise me?"

John pulled his chin down to press a fond kiss to his lips. "I promise," he assured him. "Trust me. I'm a doctor."

Sherlock snorted, taking the bait; the argument around the adage was an old one between them. The rattling from outside quieted slightly. "John, you are aware that your medical qualifications do not automatically make you more trustworthy," he said for the umpteenth time.

"I'm your doctor," John laughed. "Does that help?"

The Vulcan smiled, a genuine one that warmed the corners of his eyes. "Yes," he agreed, placing his large hand over John's where it cupped his jawline. "That helps."

John stepped forwards, almost falling over as the floor jolted underneath him, and folded Sherlock into a tight hug. "I promise, Sherlock," he repeated earnestly, grinning as his friend's arms wrapped around him and a strong nose pressed into his neck. "I'll keep you safe, I promise."

Something below them screamed, a horrible sound of anger and agony; John tried to disengage from the hug, to run and help whoever was making that sound, but Sherlock tightened his hold on him, keeping him in place. "Don't let go," he pleaded. John obeyed him, trying to shut out the screaming. This was Sherlock's mind, surely he knew what was making it, would know if it needed to be dealt with.

The noise grew and swelled and intensified until the two of them trembled with it, burying their faces deeper in each other's shoulders to shut off their ears to it. John could feel Sherlock's heart rate speeding dangerously higher than his already frightening base rate, his arms trembling from the strength with which they were clutching John to him, his jaw almost cracking from the way he was clenching his teeth. "Sherlock," he said quickly, stroking a hand through his hair to try and calm him down. "It's all right, I'm here, you're okay," he lied soothingly.

The screaming peaked, so loud and intrusive that John worried their eardrums would pop and he held Sherlock tighter to block out the pain of it: then, quite suddenly and without warning, everything stopped.

John held his breath, but the only noise in his ears was Sherlock's panting. The floor remained steady under his feet, and the only thing that attempted to assault them was Redbeard jumping up to lick at John's fingers fixed around Sherlock's waist.

"Are you all right?" he asked his friend softly, stroking one hand up and down his back. "Are they… gone?"

Sherlock laughed weakly. "Never better," he assured him. "I happen to have an excellent doctor."

Slowly, he loosened his hold on John and attempted to stand on his own feet, swaying slightly. John smiled at him. "This doctor is recommending bedrest," he said firmly, and then frowned. "Can you get rest inside your own head?"

The science officer snorted lightly. "Not while you're in it," he replied. "I'm still unconscious. You need to break the meld, and I want to see what happened to the creatures when they left me. Then I will rest for as long as you want, doctor."

John raised an eyebrow. He doubted his friend would stay willingly in the med bay for longer than a day; once he had woken up, John would have to strap him to the bed to keep him there like he usually did.

Sherlock's lips twisted into a wry smile, like he was thinking exactly the same thing. John couldn't help but laugh. "All right," he said, leaning forwards quickly for another kiss. "I don't really - I've never melded with anyone before, I don't know how to break it. What do I do?"

"Remember that this is all inside my head," the Vulcan told him, his deep voice as rich as homemade treacle, seeming to surround John's head until he was submerged in it. "That you exist outside of my head as well."

John snorted. "But it's so nice in here," he said lightly. "I don't know how you can bear to leave."

The scientist raised an eyebrow. "Some things are better in the real world, John," he said sagely. "Besides, you're out there."

"I'm in here, too," John pointed out. "Several times over."

Sherlock shook his head. "It's not the same." He hesitated for a moment, then drew a deep breath in. "You're welcome to come back," he said tentatively. "I mean… we could meld again. If you wanted."

John smiled, flattered at the trust Sherlock was displaying to let him into his mind when his life wasn't hanging in the balance. "I think I'd like that," he replied. "When you've rested a bit." The Vulcan rolled his eyes good-humouredly. "So how do I get out of here?"

"Remember how you got in," Sherlock told him. "I know T'Penya helped you, but I'm guessing she told you to think of your mind as separate from your brain - to think of your mind travelling into mine through your fingers?" John nodded. "Well, now you have to remember that your body is still where you left it, and imagine the version of you that is here reaching out to it, so that it can travel back through your fingers into your head. I'd imagine T'Penya will still be in contact, she'll feel you reaching out and help you if you need it."

John breathed slowly. The idea that there was an entire castle in Sherlock's head was suddenly a strange one, like he'd almost forgotten it, and the fact that he was himself in here made it even harder to believe that he was really just made up of thoughts in someone else's mind. "Okay," he said. "I'll see you on the other side, I suppose."

Sherlock grinned. "I look forward to it, John." He leaned down for one last peck of their lips, and then rested himself against the wall with a mock-salute.

He thought of the med bay, where he had put his hands on Sherlock's temples and fallen into his mind. He tried to imagine himself floating upwards towards the castle's ceiling, as though he could still see his hands reaching through the cloudless sky.

Something cold touched his left temple, and John jumped, his eyes opening in fright; T'Penya grinned at him, withdrawing her hand from his face. "Very nicely done, sir," she said brightly. John gaped at the med bay, the transition so sudden he could barely believe that it had happened.

Captain Adler cleared her throat. John spun around to look at her and almost fell over; his head seemed considerably lighter than it had been in Sherlock's mind, the world around them unnaturally sharp and clear. T'Penya's arms fixed themselves around him, holding him up. "I would suggest that you rest, sir," she said firmly. "Melding can be draining even for the psi-able."

"What happened to them?" John asked Adler, allowing the Vulcan to help him to sit on the end of Sherlock's bed. "The creatures?"

The woman crossed her arms, glancing behind her. John looked: the floor right outside his office was covered in a thin film of dust. "They disintegrated," she explained, grimacing. "They weren't happy about it. The screaming was awful."

John shuddered to remember it. "It was worse in there," he told her, looking over at the still-unconscious First Officer. "How is he?" he asked Molly, whose face was pale but smiling.

She pulled at the stat monitor until it was angled towards John. "Much better," she said, grinning tiredly. "I don't know what you did in there, but he stabilised a few minutes before those things left him. T'Penya helped to defend the rest of us in case they went for us, but they went for your office and then they sort of… blew up."

John looked at the young Vulcan in surprise. "I think some sort of promotion might be in order, Captain," he suggested. "It sounds as though T'Penya has saved all of our lives."

Captain Adler smiled at the younger woman, and for a moment John thought he saw a twinge of something familiar and intimate in her sharp eyes. Then Sherlock stirred, and everyone's attention was diverted to crowding around him as he opened his eyes. "John," he murmured.

Ignoring the others and the potential consequences of the action, John took his hand and clasped it tightly. "I'm here."

Sherlock smiled faintly. "You look terrible," he said.

"You look fantastic," John lied brightly in return. The scientist snorted.

"You're all right, though, John?" he asked, struggling for a moment to sit up and then giving up and falling back. Molly yanked the stat monitor around to examine it; John nodded in answer to the question. "T'Penya," the half-Vulcan said, looking around until he lighted on the younger officer and gave her a rare warm smile. "You did brilliantly."

She beamed at him. "Thank you, sir. You ought to rest, both of you. We'll have someone clean up what's left of those creatures and eject it just in case."

Adler cleared her throat once more as Sherlock craned his neck to see the dust on the floor. "I expect a full report from the both of you tomorrow when you've rested a little. Commander Holmes, you are relieved of duty for the rest of the week. Doctor Watson, I'll assess your fitness for duty after receiving your report."

He nodded. Sherlock too, surprisingly, didn't protest; John shared a sceptical look with his Captain, who smiled at the two of them. "Take it easy, you two," she said sternly, a lascivious gleam in her eyes. "No hanky-panky until you're rested."

John laughed as she led the others out of the med bay, one arm fixed proudly around T'Penya's shoulders. Molly hesitated for a moment, looking torn, but at John's expectant look she too departed, drawing the curtain around them and muttering something about replenishing supplies.

When she had gone, John eased himself up the bed. Sherlock met him with a slightly wary look, but when he opened his arms John slid into them easily and pressed a careful kiss to his lips.

He sighed in comfort: Sherlock was warm and smelled of Starfleet-issue soap and sweat, dimensions that had somehow been missing from the castle, though he hadn't noticed it at the time. His friend's arms slid tightly around him, and John could feel him smiling against the top of his head. "Whatever do you think she meant by hanky-panky?" he said, the tone of amusement in his voice vibrating against John's hair. "It's like she thinks we had some kind of romantic awakening back there."

John laughed. "She has a point," he replied. "One of us saw into the other's mind. There was no way that wasn't going to happen." Sherlock exhaled sharply, though in amusement or relief John couldn't tell. "She'll never let us hear the end of it," he remarked.

"Oh, she will," the xenobiologist said smugly. "You saw her with T'Penya. Any little knowing looks will be returned just as strongly."

They breathed for a moment, John feeling the weariness creep into his body and his eyes slide shut of their own accord. "Rest now," he told his friend sleepily, reaching up to pat his cheek. "In the morning I'll show you exactly what she meant by hanky-panky."

Sherlock chuckled again. "Is that a promise, Doctor Watson?"

John smiled contentedly. "Trust me," he said, unable to keep the smile out of his voice. "I'm a doctor."


Finally: I just want to mention that there are some incredible people running a charity auction for LLGS in honour of Mark Gatiss' birthday. It should go live today, I think, and you should totally check it out, and not just because I donated both whatever fic-writing skills I have and a signed copy of one of his Lucifer Box novels.