Sherlock was experimenting on the kitchen table. John was reading the newspaper on his armchair. Mrs Hudson was downstairs, taking her 'herbal soothers'. All was well.

Suddenly, there was a buzzing in John's pocket. He surreptitiously withdrew his hand-held device and checked it.

Harry's face grinned up at him from the screen. He motioned for her to be silent, eyes widening; then got up quietly from his chair and hurried up to his room, muttering something like, "Got to check my email."

Sherlock seemingly paid no attention, concentrating hard on his titration. As soon as John closed his bedroom door, however, his head snapped up, and he stood up silently as a mime and followed John upstairs.

John sat again on his bed, door open a crack. Sherlock eased it open as much as possible without it creaking, then concentrated on the voices from within.

"…last time," Harry was saying apologetically. "Ran into some Vogons. Well, I say ran into. It's entirely possible they were trying to get their ship back."

John rolled his eyes, but he was grinning. He looked happier, and more at ease, than Sherlock had seen him in a long time. "I thought you weren't going to steal anything else, after that run-in with the Judoon?"

"You make me sound like a felon, John," she said, pretending to be hurt.

"Why have you called this time?" he asked her. "I thought you would call me sooner."

"Yeah, sorry about that," she said. "Got distracted. Anyway, I need your help."

"With what?"

She pursed her lips and leaned forward conspiratorially. "I lost Dad. I've been looking for him for months. And I've found him now. Well, sort of. I need your help."

John started to look excited, but caught himself. "I can't Harry. I'm in the middle of a case. A big one."

"I'm intrigued. Tell me more."

"There's a man, here in 2010, by the name of Sherlock Holmes. He's a detective."

Harry laughed. "That's a heck of a coincidence."

John didn't smile. "That's the thing, you see. It's not. The Sherlock Holmes we know, Conan Doyle's character – he doesn't seem to exist anymore. I've looked everywhere, and he's just…gone. There are no records of the fictional detective. The only Sherlock Holmes now is my flatmate."

She frowned. "But that's simply not possible."

"Like it or not, that's how it is," John said grimly. "So I'm here, trying to figure out what happened. I can't go off for long periods of time, Harry. I have a life here now. And a wife," he added as an afterthought.

Harry didn't mention the wife, instead studying him almost pityingly. "You have been gone a while, haven't you? We're Time Lords, John. We control time, not the other way around. You can go away for years, and be back in time for tea."

John's face slowly began to brighten as he remembered. "When can you meet me?"

She smiled. "That's the spirit. Now, London…are you anywhere near St. Bart's Hospital?"

"Right around the corner, almost," he said. "But why there, of all places?"

Harry shrugged. "I have history there. Be on the rooftop, 10am tomorrow. We're going on a Dad-hunt!"

They both laughed, then Harry terminated the connection. John sat back with a smile on his face. He could practically taste the adventure waiting for him the next day. Sherlock, meanwhile, slipped back downstairs noiselessly, to think over what he had heard.

The next morning, John put on his coat. "I'm just going out, Sherlock," he called into the living room. "Back in time for tea."

Sherlock didn't move from his position lying on the couch. He gave no indication of having heard John, who sighed and went outside. He stopped and did up his coat, pretending to shiver in the cool winter air.

A second after the front door banged shut, Sherlock's eyes flew open. He swung his legs around and stood up, hurrying downstairs and pulling on his coat. The door closed silently behind him.

-o0o-

John stood in the middle of the rooftop, looking around impatiently. Eventually, there was a vworp, vworp sound behind him, and he spun around.

The blue box stood behind him in all its glory, lights shining brightly. John felt his hearts leap, but kept a neutral facial expression.

The door squeaked open, and Harry poked her head out, looking around until she saw him. She was wearing a green T-shirt and black trousers, with practical boots, just like normal. She hadn't changed a bit since John had last seen her, despite decades passing for her. She looked a little older around the eyes, but aside from that, there was no change.

Upon seeing John, her mouth formed into a large smile, which faltered when she saw his face. "And what sort of a time do you call this?" he asked disapprovingly, tapping his watch.

Harry glanced at hers. "Two minutes past ten," she said, before looking up at him guiltily.

John mock-tutted at her tardiness, then stopped and grinned. He crossed the space between them in two bounds, and pulled her into a tight hug. "It's good to see you," he murmured into her ear.

"You too, Johnny," Harry said, returning the hug. Then she pulled back and held him at arm's length. "How've you been? You look terrible."

"Thanks," John told her. "I've been really good, actually. Life's slow here, but that suits me just fine. I wanted to settle down, you know, after the War."

She nodded. "Yeah, I feel the same." John raised an eyebrow, and she elaborated. "Not in the same way as you, of course. Just…wanting to get away, to do something different. So I travelled the universe, while you shut yourself up in this little country."

"Don't let Dad hear you calling it little," John warned. "He's very fond of this place. And so am I."

"I can tell," Harry said, indicating the wedding ring on his finger. "What's her name, then?"

John hid his hand behind his back bashfully. "Mary. Mary Morstan."

Harry wanted to laugh, but noticed that John seemed tense when talking about Mary. She decided to change the subject. "Can you show me where you live? You said it was just around the corner, right?"

He nodded and led her over to the edge of the roof. He put an arm around her shoulders and pointed. "See that red roof there? I live right behind that, at the moment."

She frowned. "Bit small, isn't it?"

"Says the woman who's flying around in a telephone box."

She laughed. "Point taken."

It was John's turn to change the subject. "You said you'd found Dad."

Harry's smile vanished, and her face turned grim. "Yeah. Well. Sort of. I found his TARDIS."

John raised an eyebrow. "I can see that. Is this all you've got? His TARDIS?"

"Well, that's not all!" she said defensively. "There's also a warning inside, but I can't understand it."

"So you thought I could help you."

"I think Dad's in trouble, John. We could save him. Think of all the times he's saved us. Saved other people, other civilisations, all around the galaxy. And now we can help him. What do you say, Johnny? One last adventure?"

He smiled. "In that case, how could I possibly refuse?"

Harry held out her small hand, and John took it in his larger one. Together, they walked towards the blue box, and went in the open door.

John stopped inside the door and looked around the control room. "He's redecorated."

"I know," Harry said, skipping over to the console. "I don't like it either."

He shrugged, following her to the middle of the room. "It's okay, I guess. How've you been, old girl?" he asked, this time talking to the console which reached up to the ceiling.

It mumbled in response, lights flashing. "It's been a long time for you, hasn't it?" John said in the way someone might talk to a well-loved pet. "I've missed you."

Over the other side of the room, Harry frowned. "John, take a look at this."

He hurried around the console. "What's up?"

She pointed. "There's a strange warning on the projector. It's saying there's another person on here, but they're unidentifiable."

"Impossible," John told her. "A TARDIS can identify anything."

"Not this person. It doesn't even know where on the ship they are."

He glanced around, suddenly gripped by fear. "So you're telling me that there's someone else here, and they could be anywhere?"

Harry nodded worriedly. "Swimming pool, library, broom closet, even that little room that has nothing in it except for a sink."

John noticed another alert, and read it quickly. "The TARDIS is panicking. It's going to shut down any second now."

As he said the last word, all the lights turned off simultaneously, and the engine sounds froze. The only light was the soft glow of the console, barely enough for the siblings to make out each other's faces.

They looked at each other, then slowly turned so they were standing back-to-back, staring out into the darkness. Harry reached her hand back to grasp John's. "I'm scared," she whispered.

"So am I," he admitted in a whisper. "I'm hoping I'll wake up and this will be a bad dream."

There was a pause when neither spoke. After a moment, John said, in a slightly louder voice, "I don't see how this is possible. I didn't think there was a creature that was undetectable to the TARDIS. I've certainly never met one."

Harry had just opened her mouth to agree with him when a very familiar voice spoke. "Actually, John, you have."

They both spun around to see a figure on the other side of the console, the view distorted through the glass of the rotor. It moved to the side, and John took an involuntary step backwards.

For standing there, the dim light of the console casting green shadows upon his face, was none other than Sherlock Holmes.

Harry froze, her eyes narrowing. "Who are you?" she demanded.

John seemed lost for words. He blinked once, twice, and shook his head. Then he cleared his throat. "Sher- Sherlock?"

"Hello, John," the consulting detective replied in his rumbling baritone.

Harry was staring between them. "You're Sherlock Holmes? John's flatmate? How did you get in here?"

He looked at her. "You left the door open when John was showing you where we live. I merely slipped in while you weren't looking."

"You gave the TARDIS a panic attack!" she told him indignantly.

Sherlock addressed them while walking down the stairs towards them. "Ah, yes, the TARDIS. Your ship?" he inquired, popping the 'p'. "Very nice ship. It appears to be bigger on the inside. Or is it smaller on the outside?" He stopped, one hand resting lightly on the console. "Either way, it seems impossible. Like the conversation you had yesterday. I heard you, John.

"You know," he continued, "all this time, I've been searching for cases to keep me occupied. However, all this time, there was a case, a big case, sitting in front of me drinking tea. The case of John Watson."

Sherlock was leaning right in towards John, staring into his eyes. John did not move, just stayed where he was, staring right back at Sherlock.

"Go on then," he said. "You're good at deductions. Deduce me."

Sherlock frowned, continuing to display his total disregard for personal space. "You're very old, aren't you?"

John stared back at Sherlock unflinchingly. "Older than you will ever be," he said, much more calm than he had been less than a minute earlier.

"There's so much in your eyes," Sherlock mused, straightening up. "I thought it was the war, but there's more than that, isn't there?"

"These eyes have seen things you can only imagine, Sherlock Holmes. Countless horrors from beyond this world."

"What Harry said to you yesterday, about time. 'We control time, not the other way around.' What did that mean?"

John pursed his lips. "I'm not who you think I am. I'm not even what you think I am. I'm not human, nor is Harry."

"What are you then?"

"Time Lords," Harry said from behind Sherlock. He spun around to see her staring up at him. "Aliens, at least to you. We're from the planet Gallifrey, in the constellation of Kasterborous. We are each hundreds of years old, and currently looking for our father, who is closer to a thousand years old. Oh, and we're standing in a spaceship and time machine, which appears much smaller on the outside than it is on the inside. Any more questions?"

Sherlock considered her. "Harriet Jennifer Watson, I presume?"

She nodded. "That's my name in English."

"And in your language?"

"Names have power," she said simply.

He frowned. "You're not an alcoholic."

She smiled slightly, for the first time wince Sherlock had revealed himself. "What's John been telling you?"

"He didn't tell me anything. His phone did."

Harry looked over at John. "Are you still using that old one Clara Oswin gave me?"

He shrugged. "It fits with the time period."

Sherlock spoke up. "Time, yes. Time Lords. Aliens that control time, or so you say. Tell me, how exactly does that work?"

John sighed. "This ship. The TARDIS. Stands for Time and Relative Dimension in Space."

Sherlock turned to Harry. "You said it appeared to be smaller on the outside. Why 'appeared'?"

"The blue box on the outside is a gateway," she explained. "This is another dimension we're in now."

"And how big is a dimension?"

"Infinite."

Sherlock nodded vaguely, and glanced around. John sighed again, and pinched the bridge of his nose. "Look, Sherlock. What are you doing here?"

"You mentioned a mystery. I'm here to solve it."

"You're the mystery," Harry said. "You shouldn't exist. You don't exist, according to the TARDIS. You have mass, but you do not exist."

"Speaking of the TARDIS," John said, "we should probably try to get some more lights on." He reached over and flipped a few switches, then typed something into the keyboard. The lights flickered on, and they could see each other properly for the first time.

"How can I not exist?" Sherlock asked calmly. However, John could see that Sherlock looked almost worried, an alien emotion for the normally calm, in-control man.

Harry shrugged in answer to his question. "How can you be in an infinitely large telephone box talking to two aliens, one of whom was your flatmate for years?"

John took pity on Sherlock and explained. "How well do you know the works of Arthur Conan Doyle?"

"Reasonably well. I read most of his stories in university."

"Well, in the world that Harry and I know, his most famous stories are about a Victorian detective called Sherlock Holmes. He has a friend called Doctor John H. Watson, and a landlady called Mrs Hudson. Dr Watson narrates all the stories but four. Is this sounding at all familiar?"

Sherlock was frowning. "But that's impossible."

"Yeah. Welcome to our world," said Harry.

He looked around the TARDIS, then back at the siblings. "So I'm a copy, then? A copy of this fictional detective?" He stared at John, a helpless look in his eyes.

John put a hand on his shoulder. "I'm sorry, Sherlock, but it appears you are."

"How about Moriarty? If I wasn't around, he wouldn't have been stopped all those times."

"He was in the books as well," Harry said gently. "So was Mrs Hudson, so was Lestrade, so was Mycroft, so was Irene Adler, so was John."

"So you're a copy as well?" Sherlock asked John quickly.

"Not really. My name isn't Watson, it's just a name I picked up from a gravestone. I'm fulfilling a prophecy, more than anything else."

"But why? And how? How do I know you're not lying to me?"

Harry picked a book up off the console and chucked it to Sherlock. He caught it easily, and scanned the cover. "The Hound of the Baskervilles, by Arthur Conan Doyle," he read. "'A Sherlock Holmes Mystery'. Is this where you get the titles for your blog from, John?"

John blinked. "Um, yes," he said. "You don't seem very surprised."

"So, your ship doesn't recognise me because I don't exist?" Sherlock asked Harry, changing the subject.

She blinked. "That's right. John just told her that you were safe, so she's stopped panicking."

"Your ship is female?"

"Essentially, she's a matrix inside a machine. It's hard to explain. She can hear us talking, when she wants to."

The TARDIS console rumbled and a few lights flashed, as if agreeing with the statement.

Sherlock opened his mouth to ask another question, when the floor suddenly started to shake. The ship lurched, unbalancing everyone first one way, then the other.

Harry and John grabbed the console with practised ease. "What was that?" Harry shouted over the sudden noises from the TARDIS.

"Turbulence in the time vortex," John replied, checking the monitor.

"But we're not in the time vortex!" Harry yelled in confusion.

John grabbed a hammer from under the console, and whacked the console. The ship slowly stabilised itself.

"I think she took us there to shake off the intruder," he said, when things were calm enough for him to be heard. "Without asking, I might add," he said pointedly, glaring at the time rotor.

"Speaking of the intruder," Harry asked, "where is he?"

John glanced around. Sure enough, Sherlock was nowhere to be seen. "Sherlock?" he yelled, suddenly worried.

He was answered by a low groan from the other side of one of the coral struts. "Sherlock!" John said anxiously, running around to see him.

The detective was lying on the floor, head resting against the coral strut. He had apparently been thrown through two branches by the jolting. His eyes were closed. "Can you hear me?" John asked clearly. "Are you all right?"

Sherlock's eyes flickered open at the sound of John's voice. He tried to sit up, but could not. "I…I'm not sure," he said shakily.

Harry had followed John, and was also crouching at Sherlock's side. "John," she said urgently, "he's bleeding."

John looked at the back of Sherlock's head, where his sister was pointing to, and cursed in Gallifreyan. "Let's get him to the med bay."

Together, the Time Lords carefully picked Sherlock up and carried him through the door into the corridor, despite his protestations. John sat him down on a small bed, while Harry opened a cupboard and looked inside.

"I'm fine, John," Sherlock complained.

"You've got a deep cut," John told him. "You would need stitches for that."

"'Would'?" Sherlock asked. "I don't need stitches because…?"

"Because of this," Harry said, walking over to them holding a small bottle like a medicine bottle. She gave it to John, who took off the lid and poured some liquid onto a cotton ball. Sherlock could swear it was smoking.

"This won't hurt a bit," John said, before gently wiping the cut with the cotton ball.

"Ouch!" Sherlock said, and jerked backwards. "That did hurt!"

"I lied," John said calmly, putting the lid back on the bottle.

"What was it?" Sherlock asked, gently touching the area where the cut was. It appeared to be healed.

"On a basic level, it melts your skin and fuses it back together. You don't want to know the details," Harry explained.

"Nice," the detective commented.

"You should sleep now," John said worriedly. "The serum isn't intended for human use, and you might experience some side effects."

Sherlock stood upright. "I'm perfectly fine, John," he said dismissively. "My body is merely trans-" That was all he managed to say before he collapsed into Harry's waiting arms. With John's help, she lifted Sherlock onto the medical bed, and they left him to sleep.