A/N:I am sure that I am not the only one who has thought of the similarities, and I have by no means listed them all and I may have not thought this through or accurately because I have only seen four full seasons and one episode of the fifth in Doctor Who, so... I hope you all enjoy! Plus, let me warn you, I feel that I am terrible at characterization so I warn you now, be prepared. PS. please tell me if you feel that it ought to go in the crossover section, it isn't really one, but if a few people think it should then I will move it.

Disclaimer:I do not own Sherlock or Doctor Who.

"Then why do you stay with him! How can you, if he's- if he's so impossible?" She had cried as if she knew very well how weak his argument had been. She probably had, he conceded.

He had tried to answer her, he really had, but all he had been capable of doing was opening and closing his mouth several times. Janice had stood there, just looking at him and waiting for an answer, but seeing that one wasn't forthcoming, she had given a slight scoff and walked away. And that had been that. No more dates, no more sweet kisses, and no more Janice. All that he had now were—admittedly less than ideal—memories and a question that he didn't know the answer to.

Why did he stay with Sherlock? How could he stand to be around self-diagnosed sociopath, and a man who appeared to be a psychopath to so many people?

No, he did know why. It was instinctual, and that was the problem. How could he explain to anyone when he couldn't properly describe it to himself? He had no words for 'why'. It just was.

But if he could put his decision into words…

First, he supposed, he would have to explain the man himself, what he saw that apparently no one else did. It was everywhere, in the little things. Like the way the man would laugh with John after a case; the way his face would lose some tension as his deductions were proven right. Then there were the times that were few and far between where Sherlock would listen to John and when he would ask John to try and deduce. There was the way that he would soak up any praise from his friend like a little child showing off a scribbled drawing. Then there was the unholy racket he would choke out of his precious violin that would miraculously turn into something lulling after a particularly trying case was finished.

Yes, Sherlock's heart certainly seemed tiny but, it really was much bigger than it appeared. It- It was like the TARDIS—bigger on the outside than on the inside. John smirked at the analogy. Plus, there was the way it was either entirely overlooked or looked completely out of place wherever it was. Only those who understood it and had been granted a glance, no matter if it was only slight, inside it could gain any appreciation for it.

Donovan and Anderson most definitely did not appreciate even the idea that Sherlock possessed a heart. They hadn't been aware or lucky enough to see its presence. But John –John had. He could and did appreciate how rare it was for anyone to gain a foothold in the Consulting Detective's heart.

A triumphant warmth spread through John at the success his thinking had achieved, but too soon his face fell. He couldn't very well try to save a relationship with that analogy. At the very worse a girl wouldn't get the reference or think that he was mocking her. Most likely they would think him crazy or obsessed and dump him anyways.

He groaned. How else could he describe his flat mate?

No matter how he tried he couldn't quite…form the words…or…

No. There was no way he could describe him that made even the slightest sense. The man was just a bundle of contradictions. How could he say that the man was a genius, but awfully ignorant? Or that the man was, despite appearing fit, terribly unhealthy? No. No. He couldn't.

But perhaps he could explain why he stayed. Or the simplest reason for it.

It was nothing less (but so much more) than the fact that the man had saved him. Perhaps had not physically saved him—at least not at first—but mentally Sherlock had rescued him. He had been in a tough spot when he first got back to London, and then the man had deduced his way into the medic's life. It was much like if he had still been in Afghanistan. If a comrade had saved his life there was no way that John would leave him to die in turn. Somebody might argue that it wasn't the same; Sherlock was hardly in any danger.

In response to that, John would only be able to smile pityingly and direct the sadly mistaken person to his blog. If it wasn't a case then Sherlock would do himself in, there were so many ways it could happen and John shuddered to think of the possibilities. As a doctor it was his responsibility; as a friend it was what he wanted.

Yes, that would do. No one could argue against that and if they did then they weren't worth it. Yes, yes. It was much better than the TARDIS theory. Except personally, John really did prefer the Doctor Who reference. He could only imagine what Sherlock would think about being compared to an illogical phone box. But, if John had any say, no one would learn of that particularly embarrassing comparison.

John sighed as he slowed to a walk. Earlier in the evening he and Sherlock had visited a crime scene. It was the fifth in a series of gruesome murders and only then had the criminal made a mistake. They had hardly been there five minutes and John was in the middle of his third compliment when Sherlock had suddenly frozen until he was standing ramrod straight. There was the familiar expression of cobwebs being cleared from his eyes, and a soft 'Beautiful,' that was barely breathed, and then he was flying out of the room.

John had tried to follow him, but he had been stunned by how quickly everything had happened all of a sudden, and he'd had no idea where Sherlock was headed. He quickly lost track of the man. Torn between annoyance and fear he had texted Sherlock. He had no delusions that he would receive a reply so he sent a text to Lestrade asking him to message John once the DI heard from Sherlock.

For now John resolved to pick up some coffee from the nearest café and perhaps try to deduce on his own. Perhaps he could ease his worry. It wasn't often he was left behind after that first murder, but it did occur on occasion. It was often enough that he knew it was useless to try and figure out where his friend had gone. The only thing he could do is try to not panic.

Around an hour later, John was sitting in a small coffee shop by the window, when he received a text. It was from Lestrade and it told John the address where Sherlock had apprehended the murderer.

John was out of his seat before the address had fully registered in his head. Once it did, John was surprised to realize how close the location was to the coffee shop. At the same moment, John registered sirens in the distance, and though he never saw them he knew where they were headed. He picked up his pace and a few corners later he saw the sure signs of Sherlock's presence.

The area had been blocked off and there was a crowd of people craning to see what had happened while others ducked their heads and quickly passed by. And there was the ambulance with the paramedics just exiting the vehicle, quickly and efficiently. To anyone else, it would appear to be a normal crime scene, but John knew better. There was Lestrade, looking quite harried and frustrated, arguing with a very annoyed Donovan. Out of the building came the paramedics with a body on a stretcher and John felt fear clutch at him. He shoved his way through the crowd, not apologizing at the grumbles the people he pushed threw his way. It really didn't matter. All that mattered was the possibility that Sherlock could be hurt.

"I'm sorry sir, but civilians are not allowed beyond this point."

The man who had stopped John from going beyond the boundaries set up must have been new for him to not recognize John. The poor officer received a glare in response to him doing his job.

"I am with Sherlock Holmes and you better move out of my way because I have connections in very high places and if you don't, things could start going very badly for you." It was safe to say that John was not in the mood for someone to be doing their job correctly. He was also more than willing to threaten Mycroft on the unsuspecting man.

"John!" It was Lestrade and he was hurrying towards John with a look of immeasurable relief. "Would you please tell Sherlock that he needs to get his arm looked at, or else bleed out?" The grey-haired Detective Inspector glanced at the pale police man and the dark expression of one John Watson. The said expression had relaxed immensely at Lestrade's words, and Gregory Lestrade decided that he really didn't want to know.

He lifted the police tape for the smaller man to duck under and led him to where Sherlock was standing in front of the building, arguing with a very red paramedic who seemed to be using several breathing techniques to try and relax. At the sight, any of the fear that had remained vanished and John began to feel quite annoyed himself. If only Sherlock would stop and think for once, instead of just thinking all the time and conveniently being an idiot where it really counted, they would be able to avoid situations like this. At the very least, they would be in these sort of situations together.

Sherlock was holding his upper arm and John could see the blood seeping through his fingers. With a sigh, John assured the red faced man that he was a doctor and would be able to attend to Sherlock's wound. Once the man had left, John gently rolled up Sherlock's sleeve. There he found a rather large gash.

"You're definitely going to need stitches for that; more than one layer by the looks of it. It'll probably be two."Sherlock submitted to John's administrations without a word of complaint and John sighed again. "You know, there's most likely going to be a day when I'm not here to look after you and you're going to have to let someone other than me stitch you up."

Sherlock continued to not say anything and John managed to beg off a needle and some surgical thread from the paramedics. He soon sat Sherlock down on the ground and started to stitch the man up. Sherlock had refused to take any pain killers (prideful idiot) and had to sit and clench his jaw through the pain. When John finished, Sherlock stood up. John followed his example. Tired, he spoke.

"Go talk to Lestrade. If you can manage to hold off questioning till tomorrow, great. In the meantime, I am going to return this and hope that you didn't rile their ire too much."

Sherlock snorted. "I didn't say anything but the truth. I didn't need their attentions. It's his fault that he thinks that he's above everybody else. If he wants people to like him, then he should conform to the masses."

"Of course, you don't care either way."

The detective shot him an imperious look. "Naturally."

"Naturally, right. Well, I'm going to try and smooth things over. Just do what you're going to do, and please, try to not insult Lestrade too much; he puts up with a lot."

Sherlock rolled his eyes "Of course not, John." And off the man stalked.

Watching to make sure that Sherlock wouldn't disappear again, John cleared up the mess and packed everything away before heading towards the ambulance where the paramedics were tending to the murderer. It appeared that he had been knocked unconscious and wasn't too terribly injured. If that was the case then hopefully Lestrade won't be too mad at Sherlock.

And there were the fates working against him, stopping John from doing anything without some sort of obstacle.

"He's going to stop waiting for you all together if you're not careful." Yep, Donovan tall and proud in front of him, once again trying to warn him off Sherlock. Honestly, you would think that by now she would have realized that John wasn't going anywhere.

"Well, when that day comes I'll know where to go." He shoved past her. Donovan wasn't about to let him go that easily, not with that sarcastic reply.

"You see? He's already rubbing off on you." Yes, Sally, I have never once in my life been sarcastic before I met Sherlock. "He's not healthy. I've already warned you. The freak. Doesn't. Care."

Now, John was really tired and in no mood for any sort of hindrance, especially in the form of slander towards the man currently in the center of his foul mood. So, it really isn't a surprise when John started pouring out his soul and concern to the Sergeant.

"I think that you don't have any idea what you are talking about! I can't think of anywhere I would rather live than with Sherlock and all his foul experiments. Sure! He drives me up the wall, but it really doesn't matter because he's my best friend! And before you even start telling me about whether he cares or not, I think I have a bit more experience on that subject than you.

"I am the one that lives with him in case you've forgotten. And as for warning me about Sherlock, let me remind you, Sergeant Donovan, that I have already given you a warning about Sherlock. Do not call him a freak." John spat the word as if the very taste of it was disgusting. "He is my friend, and as any friend who is worth being called such, I refuse to let him be insulted in front of me. Do you understand?"

The woman just stared at him, much like his girlfriend had all those months ago. Actually, like many of his girlfriends, just after or before they broke up with him because of Sherlock. The stare that asked the million dollar question, 'why.'

So, when Sally's mouth opened, John was prepared for the question that he knew was about to be asked.

"You refuse to listen. I don't understand; he's only going to hurt you. Why won't leave him."

"You're right, you don't understand." John sighed. Then, before he could stop himself, the thought that had been plaguing him until he had gotten all the quirks worked out, flew from his mouth. "He's like the TARDIS."

It really isn't surprising that the initial response to that was eyebrow-slanting confusion.

"What?"

Oh, well. John had started it, he might as well finish it.

"You know, from Doctor Who?" She nodded, but still didn't seem to understand where John was going. "Well, Sherlock is—well, his heart really—it's like the TARDIS. Not many people know it exists, and sometimes, when they catch a glimpse of it, they find they might be able to rationalize it away. But those who know, they know it exists. And they can't help but feel better for the knowledge. The TARDIS isn't perfect, it messes up sometimes, but it still works and it's—" fantastic, magnificent, beautiful, amazing, "—it's… yeah. Indescribable."

When Donovan just continued to look at him, John became embarrassingly aware of his stuttered, ineloquent explanation. It had sounded so much better inside his head.

"Right." And then she left, stepping around him. John turned to watch her leave, wondering if she was going to go gossip about how brainwashed John was with Anderson, and found himself face to face with Sherlock.

This time, his embarrassment made itself known on John's face. "Sherlock." His voice sounded slightly higher from surprise. "So, you talked to Lestrade, then?" The detective remained silent, his face inscrutable and John felt the absolute certainty that Sherlock had heard a good deal of his conversation with Donovan. Sherlock opened his mouth, and John half dreaded what he would say.

"There's a good Greek place a few blocks away; how about some lunch?"

That was when John knew that Sherlock really was all those things the TARDIS was. He was in John's honest opinion completely fantastic, magnificent, amazing and brilliant.

"I just had some coffee while you were off gallivanting with a criminal."

"I was hardly gallivanting, John, but if that's how you feel, then we shall forgo the Greek and—"

"Hold on! You haven't eaten for at least the past eighteen hours; you are not getting out of another meal. Come on, lead me to this Greek restaurant of yours."

"The owner owes me a favor. I stopped her son from accidentally eating some poisoned mushrooms that had found their way into the bin after a murderer dropped them, trying to dispose of evidence."

"Hang on, what was her son doing eating from the trash."

Sherlock gave John a look that said he really grieved for the fate of mankind. "He was four and looking for buried treasure." John was unable to contain a snort.

This is what the soldier really loved; bantering after a case. The relief and removal of the weight of a mental countdown that led to a giddy aftermath was what really made it all worth it. John reflected back on his theory of Sherlock being like the TARDIS. While some people might flee from the impossibility, and others might hate it for not understanding it—for it being alien—there were those willing to accept the truth for what it was. No matter how improbable. John was determined to be one of these people, he would stay. After all, there didn't seem to be too many people willing to be Sherlock's companion. (Now, Sherlock being a reincarnation of the Doctor, that was an interesting idea.)

Something must have shown on his face because Sherlock was saying with no inconsiderable amount of indignation, "As to Donovan, while I appreciate your coming to my defense, I must question your motives. Really, John? The TARDIS? What is a TARDIS in the first place? Please don't tell me it's a ridiculous pop culture reference."

John couldn't help it, he laughed. While few people were able to appreciate the TARDIS fully, even fewer people had a Sherlock Holmes of their own in their lives.

A/N:Thank you so much for reading! Sorry for any mistakes that I did not manage to catch.