Tony Stark had just spent the last week in his lab. At least, it felt like it. He hadn't slept in three days at best, running on coffee and whatever mystical energy that powers geniuses to work past the point a normal man would fall comatose. He stumbled out of the elevator to the communal kitchen in the top floor of the Avengers Tower. He didn't notice anything but the coffee pot in his quest for more energy.

He didn't see the large blue box sitting in the middle of the living room that was to the left of the kitchen.

But Bruce did. After all, even after a night in the lab with Tony, Bruce was incredibly observant. And it was big. And blue.

Dr. Banner skirted around the new addition to the living room with wide, baffled eyes.

"Um…Tony?" Tony grunted into his coffee mug, already swallowing down his third cup . "Did…Why is there a Police Call Box in front of the couch?"

"A wha?" Tony was obviously not coherent yet.

"There is an old British style Police Call Box in the middle of the living room. Did you put it there?" Bruce tapped the box with his pencil, half expecting it to explode.

"Are you sure you aren't seeing things, buddy? I started hallucinating, oh, about 4 hours ago. Very distracting," the super genius said. He came into the living room and blinked, taken slightly aback. "Unless our minds have somehow telepathically connected from spending so much time together surrounded by probably more than harmless material and we're seeing the same hallucination, it's actually there." A bit more intrusive than Bruce, Tony twirled and stood in front of the blue box. Handing Bruce his coffee mug, he knocked a 'rackety rap tap tappa tap' on the door. Tony smiled at Bruce's stern, bewildered look and shrugged. "Gotta find out if anybody's home."

Opening his mouth to comment, Bruce was cut off as the door to the Police Call Box unlocked with a snk. Bruce pulled Tony back by his shirt, neither letting their eyes leave the blue door. The panel swung open and a pretty, blonde, young woman popped out smiling.

"Hallo all, I'm the Doctor." She stated in a British accent, a wide grin showing off her pearly whites.

"A doctor, huh?" the flamboyant billionaire said, sliding on a charming smile. "My buddy here is a doctor, too, but maybe you can help me, miss. I seem to be hot, hot for you." Tony stepped closer to the blonde, quirking his eyebrows. In response she raised a single eyebrow herself, giggling. Behind Tony, Bruce rolled his eyes, crossing his arms. There was a scuffle from within the box and a shout and Bruce walked behind Tony to see what was happening, bewildered by it all. A thin man with seemingly gravity defying hair and a dark brown pinstripe suit came tumbling out with a strange metal instrument in his hand, which he pointed at the blonde woman.

"Don't do that again," he scolded, a hint of a smile softening the bite. He turned to the other men in the room, "She is not the Doctor." Pointing to the woman then to himself, "She's Rose Tyler. I'm the Doctor. Rose. Doctor." Switching his pointing, he turned his finger to Tony and Bruce. "You're Iron Man and the Hulk." They both nodded slightly. The Doctor gave them a lopsided, gleeful smile. "Excellent."

Bruce was wary of that tone and the man from the box. "Why is that excellent?"

"Because!" the man exclaimed, clapping his hands together. "You're exactly who I need to talk to! Well," he looked around, "two of them anyway. But you especially because you," he gestured to Tony, "own this tower."

Tony shrugged, "My company does, at least. It has – or, used to have – my name on it. So?"

"I need your permission to house some other heroes here while we deal with the end of the world," the Doctor said casually, bouncing on his heels.

"Wait wait wait," Bruce held up his hands, "I think you need to start from the beginning." He turned his head to look at Tony, "And I think we need to call the others in on this."

"Yes, let's make it a party!" the Doctor cheerily proclaimed, sauntering over to where Rose was sitting on the closest couch and flopping onto it beside her. "Ooh, this is comfy!"

Tony raised an eyebrow. "JARVIS, inform the others. Business meeting, 20 minutes, living room. Get Mr. Angry in on it too, he'll want to be in the loop."

"As you wish, sir," the voice of the Tower's AI replied. Tony was expecting them to look startled, but the Doctor just grinned as Rose giggled at the British accent.

"Your tower has a British AI? Very classy, Mr. Stark." She grinned, leaning her head back to look at him over the back of the couch.

Tony leaned on the back of the couch near her head, smirking. "Please, call me Tony. MR. Stark makes me sound like my father. Can I get either of you a drink?"

"Water would be lovely," the Doctor replied, looking around.

"I wouldn't mind a glass of wine, Tony." She made sure to stress the name change and he grinned, winking as he turned to get their drinks.

"Coming right up!" He strolled over to the bar. As he was pouring the wine, he heard the Doctor quietly comment about how he hadn't been in this New York in a long time. There's only one New York, Tony thought, unless…time traveler? It's not impossible...just highly improbable. "So how exactly did you get in my tower? JARVIS didn't inform me of a security breach, which means you either corrupted his codes, hacked in, or aren't a threat."

The Doctor held up his hands and said, "Oh, we're not a threat. Quite the opposite, in fact." At the same time that JARVIS commented, "I do not sense any ill-intent with them, Sir."

Tony handed them their drinks, smirking at Rose as he gave her the wine glass. "That still does not explain how you got in-" Tony fought the urge to roll his eyes as he heard the very soft sound of a bowstring being drawn back. "A bit early to the party, Clint."

Rose looked confused, until a voice spoke from near the ceiling that was not JARVIS's. "Tony. Who are they?"

Tony gestured to each. "The Doctor, Rose Tyler." He gestured to a nook in the ceiling."One of the resident Master Assassins, Clint Barton, aka Hawkeye. They're not a threat, Legolas."

"How sure are you, Stark?"

"Let me put it this way: JARVIS let them in. Though I still can't figure out exactly how they got in, but we're making progress." Tony finally heard the bow string relax and the soft tap of feet hitting the ground. Clint came out of the hallway with his bow still open and an arrow notched, ready to fire at a moment's notice. Rose raised an eyebrow at his weapon over her wine glass as the Doctor gave a two-fingered salute of greeting accompanied by a smile.

Clint kept his arrow locked on the visitors as others began to file into the room, all of them surprised by the blue police box in the center and the two newcomers. Pepper was especially concerned and she yanked Tony from the back of the couch and dragged him over to a corner to have a whispered argument. Thor loudly welcomed the new visitors, sitting beside the Doctor.

"I am Thor Odinson, God of Thunder!" he proclaimed proudly, his booming voice making the Doctor flinch ever so slightly.

"I am the Doctor, pleasure to meet you!" The Doctor proclaimed, equally as loud, and he shook the god's hand vigorously. Then, softer, "You're not from Earth."

"Seriously?" Rose asked incredulously, leaning around the Doctor to get a better look at Thor. "He's an alien?"

Thor nodded once, smiling broadly. "It is true, I hail from Asgard."

"Asgard, eh?" the Doctor mused. "Haven't been there yet."

"Do you think we could go?" Rose asked excitedly.

Thor was about to question them when a dark man cloaked in black leather came in.

"Ah, Director Fury!" Tony beamed, eager to get away from Pepper's reprimands. Director Fury nodded in a quick acknowledgement and was followed in by Steve, Agent Coulson, and Natasha, who went to stand by Clint. They had a short conversation in Russian and the Doctor pretended not to be able to understand them.

Fury paused, his hands resting behind his back, and gave the phone box a critical look with his one good eye, then turned his gaze on the Doctor and companion. "Who the hell are you?"

The Doctor stood smoothly and fixed the lapels of his suit. "I am the Doctor. This is my companion," he swept his arms to gesture at her, "Rose. Now that you're all here, I can ask you what I came here for-"

"First I think you need to sit your ass down and explain EXACTLY who you are," Fury commanded.

"And how you entered the Tower without using any of the doors," Tony chipped in. He held up a tablet when all but Fury looked at him. "I just checked the security cameras. That...box just appeared in my living room."

"That box," the Doctor said, going to stand by it protectively, "as you put it, is my TARDIS. It's my...spaceship, though it doesn't just travel through space, it travels through time as well. That's how it parked in your living room."

Steve furrowed his brow, trying to wrap his mind around this. "So... you're, what, a Martian?"

The Doctor rolled his eyes, exasperated. "Why do Earthlings automatically think I'm Martian? No, I'm not. I'm from a planet far, far, far away and long gone called Gallifrey. I'm a Time Lord. The last one, actually." He looked a bit sad at the end, and Rose reached out to take his hand in hers. He smiled down at her, though it wasn't a fully happy smile.

"You'll have to forgive Stars 'N Stripes here for the Martian remark, he's still getting acclimated to the new century," Tony said, patting Steve's shoulder.

"Ah, yes of course. I forgot about that detail."

"Acclimated?" Rose echoed.

"I was frozen for 70 years in ice, miss," Steve answered. Rose gave a silent 'oh' in response, her brow furrowing in thought.

Bruce came over to lean on the back of the couch, fascinated by the blue box. "How does that work, then? Time and space travel? Does TARDIS stand for anything?"

The Doctor flapped his hand in a dismissive gesture. "T.A.R.D.I.S. It's stands for Time and Relative Dimension in Space. It's a lot of wibbly wobbly, timey wimey stuff beyond human comprehension."

Tony walked over to stand by Bruce, appraising the ship. He was messing with code and information on a tablet, tapping buttons and scrolling. There was a shrill beep from inside the TARDIS and the Doctor excused himself, going inside. The door shut before anyone got a good look inside. He was only in there for a few moments, then he came back out, frowning at Tony as he shut the door behind him.

"You're trying to hack into my TARDIS," he accused, though there was amusement in his tone. Tony shrugged, not at all concerned that he had been caught in the act.

"I am inherently curious. And I like shiny new science."

"She may be new to you, but she's actually quite old." The Doctor chuckled. "We both are."

"She."

"Yes, she."

"You say that like the TARDIS is alive."

"That's because she is."

Tony narrowed his eyes slightly at the box, calculations and equations almost visible in his eyes. "Not an AI then, just an I. Some sort of advanced bioelectric system, then? Not surprised, alien technology and all. How does she travel through time?"

"Didn't you say the TARDIS was tied into a Time Vortex or something?" Rose piped in.

"Time Vortex, hmm?" Tony rubbed his hands together after setting the tablet on the back of the couch, delighted at the new challenge. He rattled off some complicated theories, about the substance of what time was and how it moved, the physics of dimensional travel as described by Jane's Einstein-Rosen bridge theory, and a whole slew of other extraordinarily complex ideas. Bruce argued some points back, adding in his knowledge. Those in the room who weren't geniuses or ancient aliens only caught the occasional word like "waves" or "particles" or "the." The Doctor, however, looked absolutely ecstatic and knelt on the couch cushions with his hands on the back, facing those behind the couch, as he explained to them the complicated physics and working of his TARDIS. Bruce and Tony only looked mildly overwhelmed, nodding and asking the occasional question as they attempted to understand the enormously advanced science.

This went on for a good 15 minutes, and would have likely gone on longer had Steve not pointedly cleared his throat and Rose said, "Doctor" in an admonishing tone, even though she was glad he had found people to talk about his sciences with. The three looked sheepish – well, Tony just raised an eyebrow at his interrupted science time – and the Doctor turned around to face the room at large again. Bruce seemed a lot more comfortable now, leaning on the couch near the Doctor's head and gazing at the blue box while he digested the new information.

"You mentioned there was a reason you were here," Steve brought up when it seemed no one else was going to speak, "What is it?"

"Ah, yes." The Doctor leaned forward, clasping his hands between his spread knees, forearms resting on his thighs. The gleeful smile faded into something far more serious. "My TARDIS picked up on some...well, I'm not exactly sure what, some sort of temporal signal. What I do know is that someone, possibly a small group or organization, intends to bring about an Apocalypse here. I plan to stop it, but I need help." He stood and turned so he could look each person in the eyes. "The Earth needs her greatest defenders. I can't do it alone this time; the Avengers are an obvious choice, but they are not the only ones we need."

Tony gave him an incredulous look. "Seriously? Who else is there?!"

"Oh, the Earth has many defenders," the Doctor remarked, leaning back against the couch, "but we only need a few more to complete the team-"

"Hold on," Fury barked, aggravated. "Who the hell do you think you are, barging in here and ordering around my team?!" He ignored Steve's look. "You have no credentials, no experience-"

"Oh, on the contrary," the Doctor interrupted, both smug and annoyed. "Just do a simple internet search for 'Doctor Who.' I have saved this world from more threats than you can imagine, and many other worlds besides. Moreover, 'your' team has free will. It is their choice whether or not to help me, not yours."

Fury and the Doctor glared at each other. Steve stepped forward to break the tension. "Will... will we be meeting these other heroes?"

The Doctor turned his gaze to him with a small smile. "Of course, Captain. How else could you work together?"

"Where will we be working together?" Natasha spoke up for the first time, her eyes trained on the Doctor.

The Doctor shrugged. "Wherever the trouble pops up, I suppose. The readings showed a large area, almost the entire globe."

"But what about when we're not all fighting?" Steve questioned. "Where will those others stay? Surely it would be best to keep us all together, so we may be better acquainted with each other." He turned his blue eyes to Tony. "Tony, surely we could house these other heroes here, between missions?"

The Doctor's half-hearted and fake protests and Fury's sputterings were ignored by the grinning billionaire. "Sure thing, Spangles. I'm rather interested to see who else is worthy enough to defend the Earth against the end of the world."

Steve nodded once, firm, his expression set. He fell into the Captain America persona, standing up straighter, his voice commanding as he declared, "Then it is settled. Avengers Tower will be the base of operations for those fighting the end of the world." Steve thrust his hand out to the Doctor while Fury and Agent Coulson had a heated whispered discussion. "The Avengers will fight by your side, sir."

The Doctor was amused as he shook Steve's hand. "Glad you're on board."

"How many rooms does JARVIS need to prepare?" Tony asked, already moving things around on a screen.

"Eight," the Doctor replied. "Six other heroes, and one each for myself and my companion here. I doubt we'll use them much, but it'll be nice to know they're here if we need them."

Tony nodded and relayed the information to his AI. The other Avengers came up to the Doctor to introduce themselves. Fury walked out after a brief warning to the Doctor about lying to S.H.I.E.L.D., his coat flaring behind him.

Tony's redheaded CEO/girlfriend, Pepper, was very sweet and the Doctor immediately liked her. "How long will you be staying with us, Mr. Doctor?"

The Doctor laughed, "It's just Doctor, and actually I should head out. Other people to ask and all. I should be back with them soon."

Thor seemed perplexed. "You will not dine with us? Come, we must celebrate our new friendships and the ones to come!"

"And the end of the world, don't forget that." Clint's dry remark came from the kitchen, where the clatter of plates and cutlery could also be heard.

Bruce smiled shyly at Rose and the Doctor. "We eat dinner as a team every day. Helps build moral and keeps us close, I guess. You are welcome to join us."

Rose smiled and tugged on the Doctor's sleeve. "We'd love to join you."