Title: "A Promise"

Fandoms: Sherlock and Doctor Who

Beta: None. My mistakes are my own.

Notes: I had written this plan for a Who/Lock story a few weeks back but I hadn't gotten the inspiration to actually write it till now. This is post-fall for John and pre-fall for the Doctor and Sherlock.

Spoilers: Spoilers for Sherlock season two ending and Doctor Who Season seven mid-season finale. Tread carefully if you haven't seen "Reichenbach Falls" (Sherlock) and "The Angels Take Manhattan"(Doctor Who).

The Doctor loved being a time traveller. It was the only thing he knew, of course, but there were certain perks to being a Time Lord. First off, there was the discovery of new planets, new species and trouble. There was always trouble when new anything was concerned. Then there were the interesting people one would meet on what felt like a normal day of the week. Some of those people he became very attached to but he didn't want to think about that now. And then there were the other worlds. Worlds closed off by the Time Lord – parallel universes that were the same just slightly different. He loved parallel universes; they were very interesting to say the least. He loved watching himself in another dimension, prancing around all useless and, sometimes, human.

This time, as he parked the TARDIS in an alleyway in some quaint little town, he looked up from his viewer and smirked. He loved this universe. Everyone was an actor, magic was only an illusion and telly's ruled all. He was just a glimmer in someone's imagination. No aliens towering over the world, no threats from the vast space above, just plain old Earth. Boring, sure, but when The Doctor needed a break, this was exactly where he wanted to be.

As he soon found out, the TARDIS didn't land in a quaint little town. It landed in the heart of London, in the middle of the night. As he stepped out of the TARDIS, touching it's wooden panel and promising to be back in a mo', The Doctor walked out of the alley and stretched. His back popped rather loudly and it felt wonderful! It had been a while since he had felt normal – or, rather, human. The Ponds had taught him how to be human, they had taught him the best of human kindness. They had transformed him into something better.

And it wasn't about to be ruined by some mugger coming up behind him. The Doctor turned back to the mouth of the alley, hand reaching for his sonic, and looked around. Nothing. He was sure he'd heard footsteps, but there was no one coming his way. With a shrug, he turned to his left and rubbed his hands together.

"All of London… where shall I start? I'll go this way!" He said walking in the general direction.

Behind him footsteps followed. The human, because it had to be human since there were no aliens in this version, was on his tail the moment he turned left, appearing beside him on the street like a ghost or a stalker, a hoodie covering his face. Strange, The Doctor thought, how this seems so normal. Like old friends, The Doctor and the stranger walked on until the suspense began to kill The Doctor.

"Soooo… hello," he told the man next to him. "Wonderful night, isn't it?" The man only nodded. The Doctor stopped walking, the man stopping as well. "I don't think we've been introduced. I'm The Doctor and you are?"

The man removed his hoodie and said, "John Watson and I need your help."

Last Year…

John had had another row with the chip and pin machine only this time it hadn't been his fault. The damn machine kept trying to make him pay twice for the same items. He had been grateful that it was late at night and only a few people had been around to see him yell at the thing like one does during a football game.

He was yelling obscenities at it as it said, in its robotic voice, "please swipe your card and try again."

"I've already swiped the damn thing four times!" John yelled throwing his hands in the air in exasperation. "What you want me to do? Go for the record?"

A store clerk approached him, her red shirt indicating she was in charge. She stepped right up to him, took his card and swiped it through the machine. And what did the thing do? It finally went through. "You have to do it slowly."

"Yeah, thanks," John muttered as the machine spewed out a receipt. He left the moment he could, not sparing a glance at the girl who had helped him; he was too embarrassed.

He made it to 221B twenty minutes later, putting down the groceries to pull out his key from his pockets. As he was turning the knob on the door, a woman behind him screamed. On high alert, John turned and saw a man on the floor holding his stomach in pain, his trench coat bloodied. Doctor mode took over as he reached the man, taking out his mobile to call for an ambulance.

"N-no d-doctors, p-plea-please," the man said through clenched teeth. "I-I c-can't … p-please."

"Alright, alright," John said with a shake of his head. "No hospital but I am a doctor. I can help you."

"Y-yes, h-h-help…" the man trailed off, unconscious.

John managed to take the man up the stairs of 221B with Mrs. Hudson trailing behind with the groceries, freaking out about the bloodied man. Sherlock was off on a case, a simple case as he explained it - Something to do with diamonds, a bomb and an elephant. John didn't see how that was simple but then again he wasn't the great Sherlock Holmes. But he was a good doctor and this man needed his full-undivided attention.

With Mrs. Hudson acting as his assistant, John managed to remove the man's trench coat, suit jacket and shirt. His wound wasn't deep but it seemed to have hit a major organ. John stopped the bleeding, stitched him up with someone Sherlock's medical equipment and gave him something to stop the pain. Together, they dressed him back up and carried him to John's room. Sherlock wouldn't like some strange man in his room, he would only have a tantrum and, after today, John didn't need another headache.

Three hours later, the man awoke just as Sherlock arrived. At once John saw Sherlock's interest pique. He threw Sherlock out of his room and told their guest to rest up a bit.

"No," John said to Sherlock. "He's injured and no."

"No what? I haven't said anything!"

"I know what your thinking, Sherlock!" John yelled. "I've seen that look plenty of times and the answer is no."

"There is a strange man in your bedroom and you don't want to know who, or what, he is?" Sherlock asked. "Why is he even here? He could be a trap!"

"He was injured. I cleaned him up," John replied, rolling his eyes. "Does he look like he's a spy? You saw him for a minute, more than enough time to deduce that. So, tell me, is he a threat?"

"No," Sherlock said, his eyebrow twitching slightly at the admittance. "But it was only one minute."

"Like I said, more than enough time." John turned back to the bedroom and said over his shoulder, "No."

Sherlock, who had begun to follow, stopped and turned away. Perhaps there was something in the man's trench coat…

The man had a remarkable ability to heal. It had been almost five hours and the wound was barely visible now. John was even able to touch it without having him flinch at his touch. It was truly remarkable.

"What's your name, then?" John asked as he checked his pulse. "I can't keep calling you, well, you."

"I- well, I don't remember," the man said, blinking as he thought about the question. "I-I truly don't remember… golly, that's new."

"New? What you mean?"

"I-I don't know…"

"I do." John turned to the door where Sherlock stood, the man's trench coat in his arms. "You're name is John Smith according to this paper." He held up a wallet with an ID card saying John Smith and the man smiling in the picture was indeed John's patient.

"Well then," John said. "Mystery solved, yeah?"

"No," Sherlock said. He came closer to the man and said, "You are a traveller, that is easy to see. But a traveller from where?"

"Not now, Sherlock," John said. "He needs to rest."

"Why? His wound is almost healed, he needs no more rest."

"Sher-"

"Let him speak," the man said from the bed. "If I'm not John Smith, then who am I?"

"Let's find out." Sherlock threw a fob watch with what look to John like scratchy lines carved into it. The man caught the watch and stared at it, his eyes blinking rapidly as if he knew he had it in his hand but couldn't see it properly. "Open it."

"Do I know you?" The Doctor asked. "You've been following me for quite a bit now. Loudly stomping around behind me. I have ears you know."

"Y-you," John breathed out slowly, tears brimming his eyes. "You said if I ever saw you again, you would repay me with a favour."

"Sorry, mate, don't know you. You got the wrong fella." The Doctor continued to walk but John's voice stops him.

"D-doctor… please… I-I must see him. You have to help me… Please." John's stared at the back of the man's head, the tears flowing freely from his eyes now. He didn't care that he looked like a lovesick sick, he just needed to see Sherlock once more. He had to see him. "Please…"

"See who?" The doctor turns back, his eyes narrowing. "How do I know you?"

"Well that was rather dull," Sherlock exclaimed throwing himself in his sofa and fiddling around with his violin. "I was hoping to be entertained for a bit longer." John and the man followed him to the living room. Sherlock turned to the man and said, "Off you go, then."

"How did you know?"

"I'm that good," Sherlock replied with a smile. "Or … I know you from your future. You told me that one day you would pop in and I would have to show you the watch you carried with you. I wasn't expecting an entire life – as extended as it is – to pop out of it. But then again, what else would a Time Lord carry about but his entire life in a pocket watch."

"Brilliant!" The man said walking towards Sherlock, his hands clasped together in a clap. "I'm The Doctor and you must be Sherlock Holmes and," he turned to John, "Doctor John Watson." John nods, confused. "What a pleasure this is, truly! I've read all the books, even the unprinted ones! You are my favourite!"

"Sorry, favourite? Favourite what?" John asked.

"He's a time traveller, John, keep up!"

In the end, The Doctor couldn't say no to John Watson. They turned back and walked to the TARDIS as John told him what had happened. The Doctor, still mourning Amy and Rory, knew the pain John must have been feeling. He had, also, seen his best friend jump off a roof to meet the jaws of death. Amy had survived the fall, however, Sherlock had not. Not even the best detective in all the worlds could survive his own death.

"His phone call to me was his note," John told him. "But I can't… he wa- is my best friend and I wouldn't be his if I didn't try to do something to stop him from… from jumping."

"Sometimes," The Doctor began, "things are just meant to hurt. I know how you are feeling, John, I do. I… I recently lost someone – two someones. They made me better and I couldn't stop them from dying. I couldn't help them. I miss then terribly but… if I look back and think about how I could have stopped it, I wouldn't be alive. I would be stuck in the past. I take it in stride to have shared all the moments we did and I live on. You should too…"

John said nothing until they reached the TARDIS. As The Doctor opened the door, he put his hand in front of him and said, "He died without knowing how much he truly meant to me, Doctor. It hurts me that he died without knowing how much I cared for him. I have to tell him at least that."

The Doctor stared at John and wondered what could have made Sherlock want to jump. The only logical reason was because he had to. Perhaps someone or something that was out of his control forced him to jump… perhaps he was saving John from harm by jumping. But in the end he did harm John, Sherlock just made it worst. Now John had unanswered questions, unresolved emotions.

He nodded. "Let's go see Sherlock Holmes."

The Doctor remained outside whilst John spoke with Sherlock. It didn't seem appropriate for him to be there; they hadn't even met yet. Sherlock was his future, a future he wasn't particularly happy to live. Not with the master detective's death being a fixed point in time. But time was a tricky thing and, from what he knew, Sherlock would be back from the dead soon in John's future.

An hour after dropping John off, the TARDIS door opened and in came Sherlock Holmes with John Watson at his side. The Doctor almost shook to his core. He was about to meet the Sherlock Holmes and he wasn't even wearing his Sherlockian hat!

"Fascinating," Sherlock mumbled as he looked around the TARDIS. "This travels through time and space, you say?"

"Yes, yes it does. Hello! I'm The Doctor. Pleasure to meet you, Mr Holmes!" They shook hands, Sherlock's eyes buzzing all over The Doctor's face before a smile appeared on his face.

"John tells me you have brought him here from the future," Sherlock said.

The Doctor only nods.

"I am to die soon, he says." The Doctor nods again, his eyes on the ground. Sherlock turned to John and said, "If you are to travel back to your time, John, you should at least say good bye to Mrs Hudson properly."

"Um, okay," John said. "I'll be back, then."

John left, the TARDIS doors closing behind him with a squeal. Sherlock took another long look around the TARDIS and The Doctor. The silence in the room was deafening. It made The Doctor nervous. Just as he was about to speak, Sherlock stood in front of him, his eyes unusually sad.

"Might I make a request of you, time traveller?"

"Anything."

"Be there when I fall," Sherlock said softly. "If you save people, as I know you do, you must be there when I fall. You can't let him suffer like this. Don't let me make him suffer. Promise me."

The Doctor nodded, a hand on Sherlock's shoulder. "I promise."