A/N: Right, okay. This is probably the longest chapter yet because there was such a lot to fit in, and no opportune moment to cut it short. Lots of explanations for the madness here! Roll up, roll up!

It is also the last chapter. I know, I'm genuinely sad that this one is finished. This verse is such fun to write, and I've had such a brilliant, unexpected, response to it - I will miss talking to you guys! D: Always feel free to drop me a PM!

In happier news: OH MY GOSH NEW DOCTOR WHO TRAILER ASDJKSLDSQ88QGDWQI!

Disclaimer: You don't need to be Sherlock to deduce this one guys; the question of my ownership is the opposite of 'Yes, I do own it.' (More's the pity.)

Warnings: One swear word. Sorry about that, John got cross :')

Review Replies:

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(For old time's sake…)

Geronimo!

John stood behind Sherlock in the hallway of 221 Baker Street, frowning and resisting the urge to rub his eyes in disbelief like they do in all the old movies. "The stairs were right here." He pointed at a blank wall. "We saw them, then we pretended not to see them, and now we want to find them they've just gone? They can't have actually vanished, surely?"

Sherlock sighed in frustration, "No, they're still here, just… hidden more effectively." He moved to run a few long fingers along the wall, watching for any dips in the seemingly smooth surface that would indicate a disguised entrance. Nothing.

"Should we get the Doctor?" John asked from his position opposite where he could remember the staircase being. "Maybe he could help."

"Probably" Sherlock muttered, now tapping at his phone keypad.

"So we're going to get the Doctor?"

"Don't be ridiculous John." Sherlock raised an eyebrow. "We're going up the stairs." And with that, he threw his phone at the wall.

Not quite as high-tech as John had hoped for, but it got the job done. He'd long since given up trying to predict Sherlock's behaviour.

Either way, it would seem that even alien technology can't fool your brain about the whereabouts of a wall when you witness a phone passing through it like a ghost and bouncing harmlessly off a previously hidden staircase. John grinned, "After you."

…..

Amy and Rory crowded around the Doctor, who was busy tapping buttons and levers on the console, before shouting "A-ha!" when the correct file appeared on the screen in front of him.

"Evophantom-" He grinned, reading through it quickly, "are brilliant."

Amy waited a few minutes to see if he was going to expand on his statement before asking the question that had been bugging her. "What do they actually look like? I mean, you said they're shape-shifters, so I'm going to hazard a guess that they don't look like that-" she gestured towards Mike, "all the time."

The Doctor spun the screen round to face her, which was currently showing a file headed 'Evophantom' with a picture of a strange creature and what looked to be a short list of credentials - rather like a Top Trumps card.

The Evophantom in the picture was quite short, dumpy, and with skin the startling colour of blue usually only seen on cloudless summer days. Her hair was a mess of tangles and stray curls, and seemed to have been in the process of moving of it's own volition when the photo was taken. The most shocking things about the image were the eyes, however. They glowed brightly in her blue face, a deep purple that the Doctor recognised from seeing the same in both Mike and John's eyes.

Well, that or the three legs. They were pretty shocking too.

"Doctor!" Rory pointed at the screen happily, and holding up one of the pictures he'd taken on the camera. "I think we've found our ash-footstep culprit."

"Indeed." The Doctor grinned, "This has rather given it away."

Amy was scanning the screen over Rory's shoulder, trying to find anything that might be of use in finding the aliens responsible for the spate of crimes over the last week and a bit. "Doctor" She interrupted The Doctor and Rory's conversation. "It says here that Evophantom are particularly vulnerable to high frequency sound waves. Couldn't that help find them?"

"It's not the best plan." The Doctor frowned, remembering how John had screamed when he'd used the sonic screwdriver in the Tardis.

"Then what do you suggest we do?" Rory interrupted, shooting glances between The Doctor and Mike, who was sitting exactly where they'd left him, and eyeing the dry toast in his lap with thinly veiled disgust. "We have to find them somehow, they've still got Mrs Hudson!"

"If I may interrupt." Mike groaned, standing up. "I suspect they'd still be at the flat. You've hardly given them enough reason to move on."

The Doctor could sense an insult in there somewhere. "Well then, to Baker Street!" He announced, flicking a switch to get the Tardis moving and barely disguising his grin when Stamford sat down sharply. Ha, that'd teach him to insult his investigative abilities.

…

Sherlock bound up the stairs with his usual enthusiasm, leaving John to take a few deep breaths and follow him up with a stoic 'we-might-as-well-get-this-over-with' expression. By the time he'd caught up with Sherlock, the detective had already pushed the door open.

Following Sherlock into the room, John was greeted with the strangest sight, and that was definitely saying something coming from the man who lived with Sherlock Holmes and had spent a few months living life as a Victorian.

Staring at them was them.

No, that wasn't the best way to put it at all. Facing them from across the room was themselves. Or at least, extremely good replicas of themselves. The only thing that had John convinced they weren't just gazing into a mirror was the fact that the two men facing them had burning purple eyes. Last time he'd checked, his had still been brown.

Sherlock was the first to recover, the men opposite them seemingly frozen in the same state of shock John found himself in.

"Who are you?" Sherlock asked, always straight-to-the-point. "And what are you doing in my flat?"

There was a tense moment of silence wherein the couple opposite them exchanged a look. Other John had opened his mouth to speak when there was an almighty crash from the doorway - and all four of them spun round to find themselves face to face with a very unhappy looking Rory, a cross Amy, and an excited Doctor.

"You came without us!" The Doctor pouted, moving further into the small room so as to leave space for Mike to stand in. When he finally arrived, that is.

"Sorry." Sherlock shrugged, not moving his eyes from his body-double. "I guessed it wouldn't take you long to catch us up."

"I'm disappointed in you, John." The Doctor frowned his way. "You're supposed to control him."

"Don't drag me into this." John replied, still stunned. He waved towards his doppelganger. "… does my hair really look like that?"

Rory glanced between the two Johns. "Yes." He shrugged, wondering when it had become a common occurrence for him to be playing spot-the-difference with an alien and actual Doctor John Watson.

"I really need a haircut." Was John's response.

The Doctor had apparently decided that they had had more than enough time now to deal with being faced with alien versions of themselves, (and hell that would never not sound strange), because he clapped his hands and stepped in between the matching sets of flatmates.

"Right" he announced, "I think we have found our impostors."

"No shit, Sherlock." John ground out. Then widened his eyes apologetically when everyone in the room turned to stare at him.

Sherlock frowned. "I didn't say anything."

"Sorry." John grimaced, "It just sounded right. Like, 'You don't say, genius.'"

Sherlock blinked slowly. "Well as long as it was a round-a-bout compliment…" He grinned lopsidedly in John's direction.

The Doctor coughed loudly, and everyone snapped their attention back to him again, just as Mike came puffing up the stairs and into view. He was now in full Evophantom form after a hurried agreement that it was probably best not to completely confuse John and Sherlock by announcing that their mutual friend was actually an alien.

"Sorry I'm late." Mike panted. "You move too fast. Far too much-" He waved his hands in the air in front of him. "-running."

Sherlock turned from Mike, eyebrows raised, to the Doctor. "Care to explain?"

The Doctor grinned. "It would be my pleasure." He stated. "You see, Michael here is an Evophantom. The Evophantom are a race of aliens from a planet a dozen or so galaxies away, best known for their shape-shifting abilities and love of literature." He paused, waving the last statement away, then continuing his explanation at double the speed. "Anyway, these-" he gestured towards the still-silent Other John and Other Sherlock, "are a couple of star-struck children who decided to try their luck at being you."

"Why?" John asked, and it sounded so deep and metaphorical that he realised he had better explain. "I mean, why us?"

Other Sherlock opened his mouth. "Because of the books!" He announced, then went silent and withdrew into himself after a sharp glance from Mike. Well, it was either the glare from Mike or the appraising look from Sherlock.

Scratch that, it was definitely the look from Sherlock. The poor kid looked like he was going to faint.

"Books?" Sherlock asked.

"We have books derived from your so-called 'blog' back at home." Mike stated, sounding so bored about it all that no-one thought to question him. Amy was incredibly impressed with his acting abilities.

"Oh Jesus." John muttered, lowering his head into his hands. "I really should spell-check it more then."

Mike shrugged one bright blue shoulder. "I wouldn't worry about it."

"Doctor, you were explaining." Sherlock prompted, having seemingly decided to just take everything said in his stride, and ask questions later. It had clearly worked better than John's 'panic slightly at everything' tactic, which had him barely moving in the corner.

"Yes." The Doctor nodded, watching as Mike glared the Other Sherlock and John into resuming their Evophantom shapes. "These two were responsible for the kidnapping of Mrs Hudson, the fire in Baker Street, and the cases you've been investigating for the past couple of months."

"The murders?" Rory shuddered, stepping back a little. "I sort of forgot about them."

The alien that had previously been Sherlock took a deep breath, rolling his eyes and glancing between Sherlock and Mike. "They weren't actual murders." He shook his head. "Just an interactive image created by a perception altering field."

"I swear to God if someone mentions perception filters again I am going to go insane." John muttered into his hands.

"I think you should probably take a break for a bit John." Amy pursed her lips, "Why don't you go and get Mrs Hudson?"

John smiled at her gratefully. "Where-"

"Downstairs in 221C." Mike answered, he'd been muttering quietly with the two child impostors in the corner.

"Right. Well. See you in a minute." John nodded, backing towards the staircase before disappearing down it gratefully.

There was another silent moment in which Mike pulled a notepad seemingly out of nowhere and began taking notes, muttering under his breath as he did so. The two Evophantom stood silently, fidgeting and taking furtive glances at Sherlock, then looking down and blushing a furious green. The Doctor looked to be avidly inspecting something outside. Amy and Rory just moved closer together and waited quietly for someone to give in and break the silence.

"You know" The Doctor said suddenly, "I think that you should probably be going."

"I couldn't agree more." Mike sighed, "We have quite a bit to discuss." He looked in Sherlock's direction. "I think you and I should probably have a talk at some point about why exactly Sherlock Holmes and John Watson are clearly experienced in dealing with aliens, Doctor."

The Doctor shuffled his feet guiltily. "Yes, well. I'll pop round when everything here is sorted, shall I?"

Mike raised an eyebrow. "Yes, thank you." He nodded, gripping the elbows of the two teenagers, then disappearing in a flurry of noise. Amy could've sworn she heard excited chattering from the two aliens; ('Did you see him? He's just like he is on the telly!', 'total OTP!') but she put it down to being sleep-deprived.

…

John knocked lightly at the door of 221C. "Mrs Hudson?" he called, as he turned the stiff key he'd collected from her flat in the lock. "Are you in there?"

He was greeted with a cheery shout. "Yes dear! Are you finished with your latest test?"

John frowned. "What? Actually - don't worry. I'm going to need to kick the door, it's a bit jammed… Can you move away from it?"

There was an audible sigh. "Of course."

After a few well-aimed kicks at the splintering door, (and John would never get tired of being able to do that again), it cracked neatly just behind the locks, and swung open to reveal Mrs Hudson sitting calmly in an armchair with a cup of tea and a frown.

"You broke my door." She accused.

John found himself, once again, without words. "Erm, hello Mrs Hudson." He tried. "Sorry about, y'know, the door."

"That's quite alright, I do expect you to fix it before you leave though."

"Leave?"

"Aren't you going back home soon?"

"I am home." John said slowly. "I live here."

Mrs Hudson frowned and leant forwards, squinting at John's face. "Oh!" she giggled, "Sorry John, dear. I thought you were the other one."

John closed his eyes and took a deep breath through his nose, holding it for a few seconds before letting it out through his mouth. "The alien one, you mean?"

"Yes" Mrs Hudson nodded. "But you're not. Can I come out now?"

John just nodded, dumbfounded. "I think you need to come upstairs first." He said, floundering a little.

"Right, of course." She nodded. "I'll just leave this here." She put the half-full teacup back on a small table next to the armchair, then bustled past John into the hallway. "Oh, look!" She exclaimed happily, pointing at the hidden staircase. "I never knew I had another floor."

John wondered if she was in shock, or actually just insane. "It was hidden, before." He sighed.

"Well, obviously, dear." Mrs Hudson turned to him, peering at his face. "You know, you don't look too well. Maybe you should go for a lie down?"

"Soon." John promised, as much to himself as to her. Then followed her obediently upstairs.

…..

Sherlock had been quizzing the returned Mike for the last ten minutes. Rory had absolutely no idea how the poor man hadn't spontaneously combusted under the hard stare of the detective.

"So this is your fault?" Sherlock folded his arms.

"As I've said before-" Mike rubbed a hand across his eyes, "This was a mistake made thanks to a hole in our security measures. I am not a security guard."

"What exactly is your job?"

"I'm a fiction man."

"Fiction man?"

"Like a fire man, but specialising in fiction as opposed to fires." Mike bit back sarcastically. "Often shortened to Fan man actually. Or fan boy. Fan girl if you're female."

Sherlock raised an eyebrow. "Why are you here then, if this was a security breach and had nothing to do with fiction?"

The Doctor decided that was definitely his cue to cut in, and he did so - waving his hands about in an accurate representation of a windmill. "Right, that's enough ladies!"

"Oi!" Amy cried, "You don't see me making a fuss!" Rory shrugged as Sherlock grinned in her direction.

"Erm, that's enough men?" The Doctor corrected himself, looking to Amy for approval. Mike groaned aloud.

"Can I leave now?"

Sherlock folded his arms, his attention back on the evophantom. "Shouldn't you pay for the fire damage?"

Mike reached into another hidden pocket and withdrew a small device, which he then threw at the Doctor. "You'll know what to do with it." He said. "Any other questions, you know where to find me." And he disappeared again.

"What is it Doctor?" Rory asked, pointing at the device.

"It's a setting designer." The Doctor grinned, "Oh, that's brilliant!"

"Setting designer?"

"I can fix the settin- Baker Street." The Doctor grinned, "The setting of your, erm, life."

Sherlock's lips quirked upwards. "Oh good, John was rather upset about the armchair."

….

"We'll be back" The Doctor promised, gripping John in a tight embrace and kissing the air either side of his cheeks. "Promise."

"Yeah, well. When you do, make sure you leave your extraterrestrial mates at home." John smiled, shaking Rory's hand while Sherlock gave Amy a farewell kiss on the cheek.

Rory shrugged. "I'll do my best." he vowed, "But I make absolutely no promises."

"That, I do not blame you for." John grinned. It seemed even the most well-laid plans disintegrated in the Doctor's presence.

The Doctor had since moved to watch the goodbyes from a corner, a sad sort of look in his eyes. He'd asked Sherlock if Lestrade had contacted him with any new cases, and been told that they had a few lined up - something about geeks and a man called 'Knight'.

He knew the Fall wasn't far away.

Mind you, he also knew that Sherlock had pocketed one of the perception filter devices from Mike when he wasn't looking. And he didn't have to check his jacket to know that the psychic paper he always found so useful was also missing. He grinned.

You never knew when it was going to be useful to create the image of a dead body, or be able to move around the country with ID that proclaimed you as someone else.

The doors to the Tardis opened when The Doctor snapped his fingers in their direction, and he turned round proudly. John grinned, and waved as Rory and Amy went to join the Doctor in the blue box. They were about to shut the door and leave when a greeting from the doorway had them pausing.

"Hello dears!"

'Panicked' didn't quite cover the look on the Doctor's face as he glanced between himself and the entrance of the flat.

Mrs Hudson strolled in calmly, holding a plateful of biscuits and with a couple of bottles tucked under her arm. She tutted when she saw them. "Leaving already?"

The Doctor looked to Rory for help. He shrugged. "I- Sorry?"

"That's quite all right, I did suspect you wouldn't hang around for long." Mrs Hudson said, patting John on the arm as she passed him and holding out the plate and bottles to Amy. "I've got you some biscuits and lemonade for the journey - you all look about ready to drop."

"Thank you" Amy smiled, taking them and sniffing the warm biscuits appreciatively. "You're a star."

"So I've been told." The landlady smiled. "Do come and visit!"

"We will." Rory promised, mouth full of chewy cookie. "These are really good." Mrs Hudson ruffled his hair in response.

"You'd be a brilliant companion." The Doctor stated, looking to everyone else for back-up. "Wouldn't she?"

"You've said that before."

"Well then." He nodded. "It must be true."

When they did finally leave, smiling and waving and full of doughy goodness, the three travellers decided they were the happiest they'd felt in a long time.

As John leant into Sherlock's side, their flat finally alien-free and Mrs Hudson back in her rightful place, he couldn't agree more.

…..

Once in flight Rory headed to the bedrooms to collect the blankets and pillows, (Amy and the Doctor had voted for making a bedding fort in flight around Venus. He'd have preferred Pluto.) Amy had followed the Doctor around the console, pushing at random shiny buttons and hoping for the best.

"So the Evophantom… could they do that with any book?" She asked, leaning her hip against the console beside where the Doctor was busy prodding at an exposed wire.

"Hmm? Oh, yes." The Doctor looked up at her, grinning. "You should see what they've done with Potter."

A/N: And that, my friends, is that. Forgive me whilst I sob quietly in the corner and clutch my 'companions and their geniuses' t-shirt to my chest.

Feedback? Pretty please? As always, I'll pm a reply to all reviews given on this chapter (: