John yawned as he came down the stairs, rubbing his eyes as he passed through the living room into the kitchen. Sherlock was already there, showing no signs of having been elsewhere all night. He finished writing down some notes, then dumped whatever he was working on in the trash, immediately looking irritable.

"Finished with that one, are you?" the sweater-clad doctor asked mildly, already knowing the answer. John didn't need to glance up from making tea to see the annoyed expression on Sherlock's face. He could practically hear the eye roll and the unspoken "Obviously."

John handed Sherlock his tea when it was ready, popping bread in the toaster and getting out two plates.

There was a certain whining tone bordering the edge of Sherlock's voice as he asked John, "When will my next case be?"

"I don't know; I can't control the clients, Sherlock." John was calm as he answered, holding in a sigh. This question had started day two without a fresh case; it was now day eight and Sherlock was near intolerable. Luckily, Sherlock had distracted himself with some experiments for a few days, but he had just finished the last of them and would be utterly bored again in–John checked his watch–20 minutes.

The toast popped up. John slathered each with a thick coating of jam and slid one plate to Sherlock. There was an unrelenting gleam in his eyes, face set in his no-nonsense expression. "Eat. You're not on a case."

Sherlock glowered at the toast and sulkily took a bite. John watched him until all of it was gone, then nodded to himself, satisfied for now, and turned to eat his own toast.

Their morning proceeded as normal: John read the paper in his armchair and Sherlock paced the living room before flopping onto the couch groaning about how incredibly bored he was.

Sherlock brooded on the couch, his back to the room, grumbling. He held out his hand toward John. "Give me your gun."

"No." John didn't even look up from his paper.

"John."

"You will not shoot any more holes in the wall, Sherlock. No."

Sherlock muttered scathing insults under his breath at John, but the doctor ignored them with a skill born from years living with the consulting detective.

Sherlock let out an aggravated huff of air and turned over onto his back, glaring up at the ceiling as if it would rain a case down on him if he only glowered hard enough.

He was blessedly silent for a few minutes, and then: "John. I need them."

John lowered the paper with a loud rustle so he could glare at Sherlock's prostrate form. "NO, Sherlock! You're doing so well! A new case will come soon, have you-"

An exasperated scoff plus a thud as Sherlock rolled off the couch cut John off. "Of COURSE I've already checked the blogs, John! AND I've texted Lestrade! Nothing, nothing! – I NEED THEM! Where have you hidden them?!"

John rolled his eyes as Sherlock stormed about, tossing papers and books and who-knows-what-else around in his hunt. "No, Sherlock. You agreed to quit. You've been clean for months; I'm NOT letting you break that streak. Play your violin or something." He returned to his reading.

He sighed; really, he had been expecting such behavior from the genius, since he had reacted similarly the last time John had made him quit his addiction cold-turkey. Back then, it had taken Henry Knight and his case, The Hounds of Baskerville, to bring Sherlock out of his mood. John hoped the next case would come soon, it had already been over a week and he was beginning to worry about Sherlock's mental state.

John didn't have work today, so he decided to catch up on the large pile of dishes that needed washing in the sink after he finished the interesting bits of the paper. Meanwhile, Sherlock poured his frustrations into his violin playing. The ex-army man winced at the horrendous screeches coming from the living room.

"Playing like a dying cat will not bring clients to our flat faster, Sherlock." John's shoulders relaxed a bit as the noises stopped. A few moments later, softer and more beautiful tones came floating on the air. John recognized it as a piece of Vivaldi's La Stravaganza–his knowledge of classical music had dramatically increased since he first moved in to 221B–which was one of the pieces Sherlock played through when he was exceptionally bored but still wanted to be in John's good graces.

A sudden, odd sound interrupted the cascading notes and the flat fell to silence around it. John could only describe it as… vworp vworp vworp. Curious, John turned off the tap and walked into the living room. Sherlock was near the window and looked equally startled. A great wind was blowing papers around, smaller trinkets flying around the room. There seemed to be a blue light flashing near the ceiling, getting stronger. Under it, a blue boxy form was starting to take shape, beginning translucent and faint but getting stronger and more solid with each pulse of light and vworp sound. It only took five vworps for there to be a very real and very there 1950's style blue police call box sitting in the living room of 221B. Sherlock put down his violin and joined John on the door side of the sudden new centrepiece of their living room. John glared at him, freaked out but trying not to let it show.

"Sherlock," there was a panicked warning tone in his voice, "did you mix chemicals in the mugs again?"

"You're not hallucinating, John."

"Like hell I'm not! There, there… there must be some gas that's being pumped into the flat or-" His voice turned angry and a bit scared as Sherlock gave him a blank, yet mildly amused look. "Don't give me that look, Sherlock! Police call boxes just…don't….bloody hell."

The door was opening. John steeled himself for whatever was going to come through, his fingers twitching; he didn't have his gun on him, an early morning decision he was regretting.

What stepped out of the Police Box was nothing at all what John was expecting. It was a man, a human looking man, with tousled yet upwardly styled brown hair and a lot of little freckles. A long brown trench coat brushed his ankles, worn over a crisp blue suit jacket and matching pants. He was wearing a pale blue button up shirt with a red tie that had subtle swirls on it under the suit jacket. There were red Chucks on his feet and a huge smile on his face.

"Allo!"

John was stock still and silent after the strange man's cheery exclamation. Sherlock just calmly stepped forward, the slightest smile on his face as he shook the stranger's hand.

"Ah, the Doctor. Finally, something INTERESTING!"

John sputtered, breaking his silence. "E-exCUSE ME?! You know him?!"

Sherlock gave John a smirk, one side of his mouth quirked up almost smugly. "Yes, I made the Doctor's acquaintance while I was…abroad. The Doctor saved my life."

The…Doctor, as Sherlock called him, was beaming and leaned his elbow on Sherlock's shoulder after letting go of his hand. "Sherlock here saved mine and Rose's lives a few times too, it was great fun." Sherlock gave the Doctor a tight lipped smile that John knew meant he was feeling uncomfortable and pushed the elbow off his shoulder, stepping closer to John again.

John was struggling to make sense of all this. "So… he's a doctor-"

"No, THE Doctor; please, John, for once, do keep up."

"But… Doctor who? What's your name? ...what?" John looked between the two taller men, who were sharing a little secretive smirk. John felt cross and left out. He folded his arms across his chest, scowling at the man who was now chatting with Sherlock as if he had known him for some time. But Sherlock said he had only met him once, yet this man, this Doctor, seemed to know so much about the consulting detective. It didn't make sense.

Sherlock was currently talking; John must have missed some of the conversation while he was lost in thought. "…you look different from when I last saw you; something big must have happened to force you to regenerate."

It was the Doctor's turn to look uncomfortable. He scratched the stubble on his chin. "Yeah…" He tilted his head this way and that with a myriad of shifting emotions passing over his face, not really looking at Sherlock, his voice dropping to a softer level. "Time Vortex."

Sherlock nodded once, like he understood or was acknowledging pain. "Ah."

John finally exploded, confused and feeling alienated from the conversation. "WHAT?! Sherlock, what the HELL is going on? Regeneration? Time Vortex? Who are you? Why are you here?!"

The Doctor brightened again and hit his forehead with his palm. "Oh, right!" His expression and tone turned more serious and he looked between the consulting detective and doctor. "The world is going to end, and I need your help to stop it. Both of you. You need to come with me. Ah-" he held up a hand, as both were about to ask questions. "No, please, let me explain. I am gathering as many of the Earth's greatest defenders and protectors. There is…great evil afoot, but I dare say no more until I have gathered those I need. The Americans have already agreed. Well," he looked both cheeky and thoughtful, and rocked on his heels, paused and started to sway side to side, "SOME of the Americans – no, MOST of the Americans have agreed. Rose is watching the scanners for the Winchester brothers." He looked at them, almost smiling as though he already knew the answer. "Sherlock Holmes, John Watson… will you come?"

Sherlock narrowed his eyes in thought. "Hmm… No."

The Doctor blinked and brought his head forward as if he didn't hear him correctly. "Sorry… did you say no?"

Sherlock looked remarkably disinterested. "That's correct. I'm far too busy-" he ignored John's incredulous "What?!" "-and it doesn't seem worth my time. But, I'll send my best man for the job." He patted John's shoulder as he passed him to lean against the back of his armchair, watching them, a tiny smirk on his otherwise expressionless face.

The Doctor looked very lost and confused, shocked even. "What? But…" He blinked a few times, trying to understand.

John was almost pleading with Sherlock, but anger and annoyance colored his tone the most. "Sherlock, what are you talking about, you haven't a case in eight days, you are NOT busy. Dammit, Sherlock, the world might end-"

Sherlock's icy blue eyes met John's brown ones and Sherlock raised his eyebrows. "Better get packing, then, John."

The flatmates glared at each other, the muscle in John's cheek twitching as he clenched his jaw repeatedly, his fingers curling into white-knuckled fists. Sherlock looked almost amused. John knew what he was doing, why he had phrased it that way, almost his exact words from the Baskerville case. And dammit, he didn't care if he was giving in, the fate of the world depended on them and Sherlock was being petty again. John stomped over to the sheep's skull on the wall and pulled a box of cigarettes out from behind it. He shoved them at Sherlock, who tossed them over his shoulder.

"I don't need THOSE," he proclaimed gleefully, his mood violently shifting from disinterested to the excitement of a kid at Christmas, "The possible end of the world, aliens, superheroes – the game is most definitely ON, John! Pack your bags, we're going to America!" Sherlock strode toward his room, then stopped and turned. "I'll be needing the couch. You should bring John's chair as well. They help me think." He turned back and continued to his room, the occasional muttering or curse coming from the room, as well as the sounds of Sherlock going through his closet and tossing things around.

The Doctor ducked his head down to John's level with a confused expression, still staring after where Sherlock disappeared to. "So…..he IS coming?"

John gave an aggravated sigh, wondering how much they were going to owe Mycroft for plane tickets. "Yes, he's a right git, but he's coming."

"What was...THAT all about, then?"

John waved him off a bit shrugging. "Oh, he got re-addicted to nicotine while he was...out of the country for a few years. He's gotten clean since, but he still gets cravings when he's bored." John grumbled to himself as he paced the living room, "How are we going to get the couch to America? Shipping costs a fortune, not to mention who knows WHAT has been spilled on it that sniffer dogs would pick up on. Planes are bloody expensive too- Hey, hold on a second!" The doctor whirled and stared at the Doctor. "How exactly did you manage to get that Police Box in here?"

The man in the brown trench coat jerked his thumb over his shoulder in a casual point. "That's my TARDIS," he corrected.

A silent stare met this response. "…your what? How does that explain anything?"

"Time and Relative Dimension In Space." Sherlock's cool voice behind him made John jump. A smirk quirked up the corner of Sherlock's mouth,. "He's an alien, John, and that's his spaceship."

The Doctor piped in helpfully, "It travels through space. And time."

Sherlock set down the large suitcase he had packed by the door of the blue box and turned to John. "Hurry up and pack. I only need to grab our laptops and I will be ready."

John puts his hands on his hips, frowning. "What about the experiments in the kitchen?" Sherlock scoffs. "And someone needs to tell Mrs. Hudson and Lestrade that we'll be gone for–" he turned to the Doctor. "How long will we be gone?"

The Doctor pursed his lips off to the side of his mouth, scrunching up his face in the process as he looks into the distance. "Ooh, tch, hard to say, really." He looked back at John almost apologetically but with the light of mirth in his eyes. "The end of the world doesn't really keep to a schedule. It does tend to drag on, though. Could be months. Years, even. This is only the very beginning of what will likely be a long battle."

John let out an inarticulate aggravated noise. "That means I'll have to quit my job. AGAIN. Sherlock, at least go clean out the fridge of body parts and put them in those biohazard bags Molly gave us. And DON'T you DARE bring them with us. I'm going to go pack." John trudged up the stairs as the Doctor curiously followed Sherlock into the kitchen. The ex-soldier meticulously folded his jumpers and jeans and other clothes, compressing them to get as much as he could in his suitcase. He ended up taking most of his closet, many of the jumpers ones Sherlock had brought back for him from his…travels. Once all of his clothes were packed, as well as extra pairs of shoes, he packed up most of the things from the bathroom, including the things Sherlock didn't bother packing–he either forgot about them, or he figured John would just pack for him, the clever git–into his old army duffle bag. He brought his luggage down and set them next to Sherlock's bags. He went into the kitchen to check on Sherlock's progress and to grab a few necessities. After all, who knows what kind of tea they sell in America and he's not sure he could deal with aliens and superheroes without his daily cuppa. Once the kitchen was straightened away, they went back to the living room. John eyed the TARDIS critically.

There was doubt and disbelief in John's voice, "How is this going to fit in that little box?"

Sherlock smirked, crouching to pick up one end of the couch. "Humour us, John."

John huffed and hefted his end up. The Doctor held the door open and Sherlock went in first. John didn't notice anything until he was all the way inside–he dropped his end in shock, jaw dropping open. He openly gaped.

"I-it..it..what?! WHAT?! It's bigger on the inside?!" He ran back out, circled the box, and tried to peer in the windows but was too short. He rapped on the wood to feel the solidity of the panels, then slowly went back inside. A careful look around the inside, then he went back out to repeat the outside inspection, popping his head in a few times. John sat down heavily on the couch that was still where they had dropped it. His shaking hands covered his face. "What...I…bloody hell. Jesus."

Sherlock was unaffected. "Yes, well we still need to bring in your chair, as well as our bags."

"How are you not freaked out by this, Sherlock?!" John demanded, looking up from his hands to glare at his best friend. "It defies physics!"

"I've already seen it," Sherlock replied, sighing as if explaining all this to John was incredibly tedious, "And it's simply far more advanced science, it's not like it's magic, John. Honestly, what IS it like in your brain?"

John bit back a scathing remark, instead helping Sherlock get his arm chair into the TARDIS as well. Sherlock and the Doctor loaded their luggage in while John went downstairs to tell Mrs. Hudson that an emergency case came up and no, he can't tell her any details and he's not sure how long they'll be gone, but they're needed in America. He promised her that rent would still be paid-he wasn't entirely sure how he'd manage it, but surely owing Mycroft a bit more wouldn't hurt too terribly, or else he could surely get a job in America-but she assured him that the flat would still be waiting for them when they returned. John thanked her repeatedly before going back upstairs and double checking for things they forgot to pack.

Sherlock texted Lestrade and his brother at John's insistence: GOING TO AMERICA. IMPORTANT CASE. POSSIBLE END OF THE WORLD. EMAIL ME ONLY THE REALLY INTERESTING CASES, NOTHING LESS THAN A 9. - SH

John sat on the couch, which had been moved to the flat area around the central control console, his hands pressed together over his mouth. It was a habit he had picked up from Sherlock, for when he was really baffled. A pretty blonde girl with a thick London accent-which John for one was glad to hear, the Doctor...unnerved him so something familiar was welcome-sat down beside him. She introduced herself as Rose Tyler, the big smile on her face making John smile back.

She looked over at the armchair, where Sherlock had perched. "Now I know why you were fighting so hard to get back to London, Sherlock, John is such a dear!" John flushed slightly and looked at Sherlock, who was not looking at them.

"Sherlock? You...told them about me?"

Sherlock glanced over. "Don't be stupid, John, of course I did. They required an explanation of my actions."

John didn't really have anything to say to that and Sherlock had already tuned him out, so John turned to Rose. "Where did you meet Sherlock?"

Rose launched into an excited retelling of their adventure in South America. Sherlock now took the time to inspect the Doctor's companion, as he had not seen her since their last encounter. It was obvious to Sherlock that the Doctor was even more attached to her than before. He was comfortable sitting very close to her and she did not protest the lack of space between them so she was fond of him too. Sentiment. She was practically dressed with her running shoes, blues jeans, and a pink babydoll tee underneath the green jacket she wore. Her voice, British-they had recently visited her home so the accent was stronger. She looked a bit older and more mature now, it was hard to tell exactly how long she had spent with the Doctor since the last time they met, and adventurous, one always has to be when they traveled with the Doctor. She was slightly above average in intelligence, not book smarts, street and common sense smarts. Witty and quick, Sherlock could tell she grounded the Doctor to a more human and sociable level. Sherlock narrowed his eyes in thought for a moment. All of that was the same as when they had first met, but there was something else... Based on how she moved her fingers in her lap, while she cared deeply for him she was still getting used to the differences between this regeneration and the last. There was also a touch of guilt in the turn of her sleeves, she had some major part in his regeneration. She looked haunted around the eyes, like she had seen the secrets of the universe; the Doctor had mentioned the TIme Vortex, so it was possible she saw into it.

She turned to talk to the Doctor, who had gotten up and was messing with things all around the control console; honestly, it looked less like a control console and more like a shiny junk pile to John, but he kept that thought to himself.

"Doctor, why don't we have a sofa?" Rose asked, her fingers playing with the blanket John had thrown over the back of it.

"We do have one-"

"Not in the main part of the TARDIS, it's all the way in the library!"

"Well, we've got the bench," was the Doctor's slightly defensive reply, pointing with his thumb at the three-person seat on the other side of the platform.

Rose rolled her eyes, grinning at John. "Yeah, but sofas are comfy! That thing is barely tolerable for short journeys!"

"Alright, next time we have to fight off an invasion in IKEA, I'll make sure we take the time for you to pick out furniture," the Time Lord retorted, grinning around the glowing column.

"I'm gonna hold you to that, Doctor," Rose warned with a smirk.

John had a feeling these two time travelers bantered like this all the time. He didn't want to interrupt their easy chatter, but he had to ask: "Where are we going exactly?"

The Doctor worked his way over to the side of the console they were on as he talked, "Normally, I'd say anywhere you want to go, but in this case we're going to the Avenger's Tower in New York City."

John blinks. "Avenger's Tower? Oh, you mean that great big STARK tower that was damaged in the Chitauri attack a few years ago?"

The Doctor turned with a big smile. "Yes, exactly!"

"He said he was amassing a team of the Earth's finest defenders," Sherlock stated before John could even ask, "the Avengers are an obvious choice."

John took a few moments to think, the TARDIS shuddering gently around them as it traveled. When he spoke, his words were slow and minutely hesitant, as if afraid the Doctor would return them to England for what he was about to say. "Okay... Them I can understand, but... us? Sherlock Holmes and John Watson? Protectors of the Earth? How can we fight aliens? Hell, Sherlock barely knows about the solar system, let alone anything beyond it!" Sherlock pouted in John's chair.

"Who said you would be fighting aliens?" the Doctor asked calmly.

John flushed a light pink. "I, er, figured, since we were in a spaceship..." He was expecting Sherlock to make a scathing remark about not assuming things, but he stayed silent.

"You might end up fighting aliens," The Doctor said after some finer fiddling with doodads on the dashboard, "I honestly don't know who exactly you'll be fighting. I may be from, well I may have VISITED the future, but that doesn't mean I know everything that will or could or might happen. As to why you were picked...you two are the best detective team of any time. Thousands of stories have been written about you. The Avengers may be able to fight, but I have always believed that knowledge is the best weapon of all. Do you understand?"

John nodded while Sherlock preened at the praise. "I...yes, thank you, Doctor."

The rest of their trip didn't take long, as a few moments later the TARDIS shuddered to a stop. They got out in a large room that looked to be some sort of storage area. The TARDIS had landed in a large square that was a similar color blue as the box and had "TARDIS LANDING ZONE - KEEP CLEAR" painted in black on a yellow border all around the edges.

A voice spoke out from everywhere, making John jump and nearly pull his gun. Even Sherlock looked startled. "Welcome to Avengers Tower, Dr. Watson, Mr. Holmes. Welcome back, Doctor, Miss Tyler."

The Doctor smiled. "Thank you, JARVIS." He saw John's baffled expression. "JARVIS is the Tower's AI unit. Tony built him, he basically runs the Tower all by himself."

Rose pushed a panel and part of the wall slid away to reveal a well-lit hallway leading to an elevator. They all got in and the Doctor pushed the button for the desired floor.