A/N: Hello, everyone! This is my very first time publishing a fanfiction in English, so please remember I'm not a native speaker, and I will surely make mistakes.

If you would point them out for me, it would be very kind of you.

Anyway.

This fic was born from a very, very, very long lastingRP I'm having with a lovely fellow Sherlockian, which, in turn was born on Omegle. In this chapter, she was Sherlock, while I was John.

I hope you enjoy reading it as much as I'm enjoying writing it.

Reviews, positive or negative, are most welcome.

The Hardest Puzzle

Chapter #1: Equivalent exchange

It was a slow day at the surgery, and John Watson was almost dozing off on his office's chair.
He and Sherlock Holmes, his crazy genius of a flatmate had been up all night, chasing a drug dealer through London's darkest alleys. They had missed him, and Sherlock had been sulky since they came home afterwards. John had been completely exhausted, but had made an effort to stay awake as long as he could, just to make sure Sherlock didn't decide to run after their escaped criminal and get himself injured or worse. He had managed to get three hours or so of sleep at most, so he was understandably tired.

His phone's screen lighted up to life on the desk, distracting him from the staring contest he was currently having with a scratch on its surface.

John, can you come to Baker St? I have something I must tell you. –SH

The doctor sighed heavily. Yes, it was indeed a boring day at work, but he couldn't just go home whenever he pleased. How many times had he told that to Sherlock? He couldn't even recall. Why bother, if the answer was always the same?
"Dull, John!"

Sherlock, I'm working! –JW

It was pointless to remind him, he knew it very well, but one could only hope. He was fully prepared for the sarcastic retort he was going to receive about his tautological observation, but it never came. His phone stayed silent for about forty-five minutes, which was odd to the point of being alarming. Sherlock never let go of something so easily, much less something which involved whisking him away from his "boring" day occupation. He frowned, tapping his pen nervously on the desk.

Finally, the phone vibrated again.

I'll be there, don't worry Dr Watson. –JM

He blinked at the text once, and it took him approximately two seconds to understand what those initials stood for. His eyed widened.

What, Moriarty? How are you answering his phone? –JW

Oh, please… I can break into the Bank of Scotland, don't you think I can answer his phone? –JM

John grimaced.

Touché. –JW

Thank you. –JM

I wasn't complimenting you.

He stopped typing for a moment, thinking. Perhaps Moriarty had just hacked Sherlock's phone, and he wasn't actually with him. Perhaps Moriarty was just trying to scare him, to make him think he had kidnapped Sherlock.

He needed to know. He finished the text.

Is he with you? Have you done something to him? Pray for your sorry soul the answer is no. –JW

You're hilarious, Dr Watson. I see why he likes you. Don't worry, though. I will take care of him. –JM

Of course, of course he had gotten Sherlock. Silly hope it was, to believe Moriarty had decided to be nice, for once.

He didn't waste another minute, and jumped on his feet, getting out of his office. He sent a quick, angry text.

You bloody bastard, where are you? Sherlock, if you're reading this, I'm coming. –JW

He reached the surgery's reception, where Sarah was typing on the computer. He cleared his throat to get her attention.

"Sarah, I'm sorry, I've got to go." He hurriedly said.

She raised her head, and looked at his face for a moment. That's all it took for her to understand.

"Sherlock is in trouble, isn't he?" She asked, deadpan.

John nodded.

"Again, I am sorry. Take off my pay check the time I'm skipping!"

Sarah waved him off.

"Don't' worry, just go. I'll see you on Monday."

John smiled gratefully at her, taking off towards the exit.

"Thank you, you're a saint!" He called behind himself.

Meanwhile, his phone had vibrated twice.

No! John, don't come, I'll be fine. –SH

Isn't that sweet? –JM

At least he was alive considered John, partially but not quite relived. He quickly replied.

Sherlock, you idiot, if you think I'm going to sit here and just wait for that psycho to murder you in a, I'm sure, very creative way, then you don't know me at all. –JW

His phone vibrated twice again, while he was calling for a cab.

And you think you can stop me, Johnny boy? I can kill you both without even blinking. –JM

John, trust me, I can handle this. Don't come. –JW

The doctor narrowed his eyes.

I could surprise you, Moriarty. Don't forget I invaded Afghanistan.
Sherlock, you know I trust you, and you also know that I won't let you face him alone. I won't risk losing you. –JW

It seemed that all of London's cabs had been sucked into a huge Black Hole, so he just started marching down the street, directed to New Scotland Yard.

This time, his phone vibrated only once.

I own Afghanistan, my dear. God, it would be sooo sad killing you. You are so cute with your boyfriend. –JM

John couldn't honestly say that he was that surprised about Afghanistan.
He decided to ignore Moriarty's insinuation, as it was clearly just an attempt to stress and frustrate him further.

You own… Never mind. Wait until I get to the Yard and I have Sherlock's phone tracked down and THEN I'll show you just how CUTE I can be –JW

Do that, and your precious little Sherlock will die. It takes much less effort and time. –JM

John cursed his own stupidity. Of course seeking the help of the Yarders was a bad idea. He was clearly not thinking properly; bit too distressed for that. In his defence, he had all the rights to be.

You try and lay A FINGER on him and I swear I… –JW

You swear what? What are you gonna do? –JM

He actually growled at that.

Sorry, so many ideas, so little space. But I assure you, I can be creative as well. Let me talk to him. –JW

I will. Not for long, though. But since I am in a good mood, I will let you say goodbye. –JM

Let. Me. Talk. To. Him. Now. –JW

A minute passed without any answer, and John didn't know what to do with himself.

Where should he go? Should he call Mycroft? Or Lestrade? No. Bad, horrible idea: Moriarty would've noticed, and that would've put Sherlock in further danger.

Damn.

Finally, he got a text.

John? –SH

He was well enough to text, then. Good. That was good.

Sherlock! Are you okay? Did he hurt you? –JW

I am fine. I'll be fine. Just stay where you are, ok? –SH

John frowned, turning the corner of a street he did not bother to recognize. He just needed to keep walking.

No, you won't be fine if I leave you where you are. You bloody well KNOW that. Don't lie to me, Sherlock. I'm going to get you out of there. If it's the last thing I do in this life. –JW

There are a lot of things to do in your life, none of them including this. I'll be fine. If I know you are away, I'll be better. So stay away. –SH

John snorted at the phone, as if the detective could hear him.

Which things, pray tell? My life is with you now, you bloody idiot. What the hell am I supposed to do without you in it? –JW

I told you, I'll be fine. As you were before you met me and you will be fine even if I'm not around. But I will be. –SH

And how are you so sure of that? –JW

I am a genius, remember? I know things that you normal people don't. –SH

John almost rolled his eyes. Sherlock managed to be arrogant via text message during a life-death situation. Only him.

Genius, yes, that you are. But I bet clairvoyant is not on the list of the many talents you have. –JW

You don't need to be a clairvoyant to know. Just… Trust me, ok? What could you do anyway? –JW

Well, I have a good aim, for instance. I'm sure you can recall. And I trust you. Always. Even if it's mental to do so. –JW

If you trust me, stay away. He will kill you, no matter how good you are. –SH

And why wouldn't he kill you? –JW

It took Sherlock some time to answer that text. In the meantime, John realized that during his wandering he had gotten to Piccadilly Circus. He wondered briefly if some of Moriarty's men were watching him, if they would kill him from where they were hiding, in the middle of that impossibly huge crowd that was surrounding him. Of course they would. Moriarty almost blew up a men in there, no more than a year and a half before.

His phone vibrated.

He needs me. Even if he will kill me there is no need for you to die as well. –SH

Needs you for what? You know it's not in my nature to sit down and watch. It makes my bad leg ache. –JW

"Where are you?" John muttered under his breath, "Give me a clue, Sherlock, why aren't you helping me?"

To play with him. He gets bored, remember? That's why he set this whole game up a year ago. I am the good guy and he's the bad guy, apparently, as Molly would say. Look it doesn't matter. We don't have much time left anyway. –SH

Of course. A game. It's just a game to him. We should tell Anderson we found a true psychopath, he would be happy. –JW

Anderson is not the one I care about, John. He says we have 2 minutes left. –SH

John stopped just under Piccadilly's huge advertising screens, breathing deeply. He needed to think, properly think. Apply Sherlock's methods. Sherlock had been home, earlier that morning, he remembered making him a cup of tea before going out. He got to the surgery at a quarter to eight, and Sherlock had texted him approximately an hour later. So, Sherlock had been home then, therefore had been kidnapped in the forty-five minutes gap between the first and the second text, or he had been captured already and had tried to get John to go home, safe, and Moriarty ruined his plan by texting him later on?

The possibilities were both plausible, and the places Moriarty could have brought Sherlock in both suspected periods of time were pretty much countless, basing his line of thought on the few data he had. The number still showed the "+44" area code of England, so they at least hadn't left the country yet.

He didn't have Sherlock's brain, but he wasn't going to give up that easily either.

He texted Sherlock back.

I should hope so. Sherlock, whatever happens, know that I will look for you in every bloody corner of London, or England if necessary. I don't care if this is a game for geniuses, or if I'll get killed. You should know that danger is not a problem for me. I won't let him have it the way he wants. I will find you, Sherlock. And tonight we will be back home. –JW

I am sure we will. But please, please just wait for me there. Please. You'll only make things worse if you come here. –SH

Sherlock, you never say please… This is really serious, isn't it? –JW

No, it's fine. Just promise me that you won't look for me. –SH

I… You know I can't, Sherlock. –JW

Why not? For once in your life just listen to me. Don't look for me. –SH

John sucked in a deep breath before texting back.

Because if something bad happened to you and I wasn't there to help, I could never forgive myself. Besides, do you expect me to sip some tea in Baker St while Moriarty holds you hostage? –JW

Why would you blame yourself? It's not your fault. You couldn't possibly help even if you were here. In fact, you would make things worse. –SH

A sense of helplessness washed over him like a cold shower; it just wasn't fair! He ought to be able to help, somehow!

Why do you keep saying that? Not better, I can understand, but how could I possibly make things worse? –JW

Because he could kill you and that would just… At least now the worst thing he can do is killing me. I can fight and I have nothing to lose. But if you were here I would be distracted because I would have to protect you as well. –SH

John noted that Sherlock seemed to selectively delete the fact that the doctor used to be a soldier, until not long ago, therefore quite capable of defending himself. Still, despite their current situation, he found oddly endearing how Sherlock thought it was his duty to protect John.

I… Sherlock I was in the Army! If anything, I have more experience with you in the matter of fighting. You DO remember that time you asked me to punch you… I can defend myself as well… -JW

It's not the same, John. He is not working alone, obviously. He can just kill you as he could at the pool. Um… This is probably the last text I am sending you, so in case I don't see you again… Thank you for everything, and have a great life, because you deserve it. Goodbye, John. –SH

John's brain decided that this could be a good time to start panicking, letting an impressive amount of adrenalin flow in his veins.

Sherlock, no! Please! –JW

He got no answer. Taking off into Regent's Street, John tried to focus on Sherlock's texts, searching for any piece of information he could obtain. Nothing, absolutely nothing. He felt like punching something, preferably Moriarty's face.

He realized bitterly that he didn't even have his gun with him.

Suddenly, his phone vibrated again, and he opened the text, hopeful.

Sorry boys! Time is up! –JM

He almost threw the phone away in a fit of rage, but thought better than that.

You bastard. You won't win your little game. –JW

Is that so, Johnny boy? I think I have already won. I was so kind to let you say goodbye. But now it's time for him to go. –JM

John could almost hear Moriarty's annoying high-pitched laugh mocking him from the few lines in front of his eyes.

I don't think so. Sherlock is far too bloody stubborn to die. And so am I. So wait for me. –JW

All it takes is a bullet, my dear. All I have to do is pull the trigger. So unless your boyfriend is Magneto or a vampire, he will die. As for you, I won't even bother to kill you. –JM

He was halfway through Regent's Street by then and still hadn't the faintest idea of where the crazy maniac had taken Sherlock. He was lost, completely and utterly lost, but he wasn't going to give Moriarty the satisfaction to know.

There's always another way for things to go. And if there's a man in this world who can find it, it's Sherlock Holmes. And sorry to say so (but not really), but he's better than you in every possible way. Oh, and never underestimate a pissed off former army doctor. –JW

And he was pretty pissed off at the moment.

The answer took a while, and he felt somewhat victorious about the fact that he managed to shut James Moriarty's mouth, even if just for a moment.

Unfortunately, it didn't last long.

Maybe he can get away, but I'm not sure if he wants to. –JM

John rolled his eyes at the screen. Was Moriarty really trying to make him doubt Sherlock's loyalty? He must've been desperate. Or completely crazy.

Yeah, right. You are insane. –JW

He didn't tell you? I guess not. –JM

The doctor stopped under a turned off street light and scowled at the screen. What was Moriarty on about?

What are you talking about? –JW

In simple words? If he won't die, you will. –JM

John Watson felt, as cliché as it sounded, the world spinning around him for a moment, and an icy shiver making his way through his whole body, Moriarty's words hanging in his brain in the genius' peculiar voice.

If he won't die, you will.

... To be continued...