John and Sherlock were chasing after one Dr. Grendel. John wasn't completely sure why, it involved Sherlock yelling 'brilliant!' a great deal and then 'insidious' and then 'absolutely perfect but inelegant.' If it was inelegant, John wondered, could it be perfect? He was rather running on too little rest and tea, begging to be able to sleep for at least four hours, just four, or one, or fifteen minutes, it had been two days and he had no idea what they were even chasing after. There were a gaggle of flustered physicists, a few distressed Austrians and a dash of Mycroft with a raised eyebrow. This was definitely one of those cases where John just needed to run after Sherlock, shoot things that needed to be shot and then sew everyone up at the end. John had slumped in a chair outside the office at the lab buildings of what uni he wasn't sure and of whom he didn't even know while Sherlock flustered around inside.

It wasn't John's preferred way of doing this, of doing cases. But he was so glad, so happy that Sherlock was finally, finally shaking off the whole Irene Adler fiasco. It was like sometimes, John thought, Sherlock thought of people in three categories. The general populous, who's main purpose was to be loud, stupid and if Sherlock was very lucky, a murder victim. That, although it was hard to understand at first, was not something personal; the general populace existed as a sort of crowd of extras. Second were the bit players, people whose names Sherlock actually made an effort to remember. Anderson, Sally, Molly unfortunately although she spoiled him awfully and obviously wanted to be his friend, the thousand little businessman who got him the things he needed and the things he wanted for free. And then the pinnacle, the blessed third category, was the real people. Mycroft was real, Sherlock childhood hero turned nemesis, likely because that was the most impressive honour Sherlock could think of bestowing on anyone. Although there were some rough waters there. John wasn't sure, Sherlock seemed the sort of child to bite people when he was pleased. Moriarty was real and fascinating, very dangerous that one, the closest thing Sherlock thought there was to himself. And somehow in the space of less than a quarter of an hour Irene Adler striped off her clothes, raised an eyebrow and became quite real. And then she was gone, then alive and ruining Mycroft's clever plane plan then dead again. That was the greatest shock of all. That real people could die. That people Sherlock cared about could die. John saw how that frightened Sherlock and made him pull into himself like a wounded animal. As impossibly fast and hard to understand this case was for John he didn't mind it if it would draw Sherlock's mind away from the wounds he carried to his vulnerable underbelly.

"We'll lose him if we wait another second!" Sherlock yelled suddenly, leaping back into the hall with the one of the distressed Austrians peering after him just as John was starting to doze. "This is better than murder! Abduction is so pedestrian! The impossible thing won't work of course…" It was at this point that John had completely lost track of the conversation if he had ever had it in the first place.

It involved a great deal of physics. Both the case and the conversation, and admittedly John's interested ran closer to chemistry and biology than physics and whatever else they were babbling about. He was also fairly sure Sherlock was deleting most of it as soon as it was poured in his head. John would have said no, would have said he needed his sleep, but when Sherlock called he felt adrenaline hum up from his heart to his fingertips and suddenly the tiredness was gone. Besides, who else was going to run after Sherlock, shoot things that needed to be shot and then sew everyone up? Sherlock shot him a grin and they were clambering through the hall and down the stairs like over excited schoolboys.

Then there was across the grassy green dislodging snogging students and into a cab, breaking into a flat (John was there for that one) stealing a planner, back in a cab and out to the middle of nowhere just in time to miss tea. John Watson was not a fan of missing anything with tea in it.

"Oh relax," Sherlock huffed in the cab as if answering the complaint of his own stomach. "We'll get you tea enough when the case is over. You'll get to drink that semi-solid abomination Lestrade insists is coffee."

John smiled his small pleased smile, tucked up tight like an origami frog, "Lestrade has a reputation to maintain as a Yarder." The recognition of his sacrifice made it alright somehow. John didn't voice a complaint.

Then they were hunched behind an old laboratory in the rain (of course, lucky John had gone for a jumper instead of just a button up) and Sherlock was vibrating pleasantly like only an excited Sherlock could. "He wants to do what to people?" John said, with his hands under his arms to keep warm. This was one of those squinting nights where his hair was plastered to his head and there was water just about everywhere. He knew how it was going to end too, with the two of them hipchecking each other to get to the shower and kettle first. Well mostly the shower. Sherlock preferred to drink tea John had made so he lurked until John had blinked and then carried out a stealthy tea steal.

"Do keep up John," Sherlock said turning his head, his long hair slicked all over his face. "Haven't you been listening?"

John couldn't help grinning at him; Sherlock looked a bit like a wet rat. Or a limpet. A little like a limpet. It was something to do with time and paradoxes and people exploding in conferences for physicists. It was all slightly incoherent at that point. His brain was focused on keeping Sherlock alive, a constant worry and keeping himself alive, also important. Everything else was, as Sherlock said, transport. He floated in his happy little war space, riding high on their friendship. It must be a friendship, Sherlock was the best friend John's ever had, for all the in flat experiments and he was pretty sure Sherlock was rather fond of him too. If nothing else it was a fierce little codependency. He understood enough, Dr. Grendel had been cut from a team of physicists before said team one some big award. He was outraged that they so dared to steal his notes. He (believed he) had a weapon that could bend time and space. He also blew up a scientist as a fancy conference. Dr. Grendel was also about to get arrested.

John had paid a little attention.

They get a quick grin to each other, John all smile lines and mouth and Sherlock all cheekbones and eyes, before they were picking the back lock and running in. Later John thought he should have asked for greater specificity.

"I'm going to erase you," Dr. Grendel had said after they burst into the room of the bare laboratory but before Sherlock could press the send button to call Lestrade and before John got his hand to the small of his back where his Browning lurked warmly. John was exceptional at hiding his Browning, although Sherlock was somehow always able to find it. John was infinitely grateful Sherlock hadn't yet accidentally killed himself, as, if he ever knew that service pistols are quite literally ready to shoot at a moment's notice in emergency situations, he had probably deleted it. It was a miracle he hadn't shot one of his feet off. Dr. Grendel had his funny gun pointed at Sherlock. John was calculating in his head the amount of time it would take him to get his hand beneath the back of his jumper and retrieve, aim and shot his gun. He didn't like the way things were going, not at all. Sherlock didn't believe Dr. Grendel's claim, but a gun was a gun. "You'll just stop existing," Dr. Grendel said. "It will be like you were never born."

"It didn't work with Dr. Connor," Sherlock replied, insultingly calm and Dr. Grendel's face exploded with rage.

It wasn't a conscious thought per se, it was more like a series of flaring realizations. He couldn't draw his gun in time, that realization was just a matter of muscle memory. After that John's brain just moved forward with Sherlockian logic toward his final deduction. First millisecond, he thought about that first case he had solved with Sherlock and all the cases Sherlock had solved. It wouldn't be good if Sherlock hadn't solved those cases. Second millisecond, John would never have survived without Sherlock there, and as much as he didn't want to admit it, he really does love the danger. Third millisecond, he wasn't that great at much anyway except ruining dates, having bad dreams and making a cuppa. Which he was actually quite good at doing.

Fourth millisecond, will this block the bullet, yes? Good. Wait, not a bullet… Fifth millisecond, what is that?

Then his rapid thoughts dissolved into pain, hot white pain. It destroyed everything. Burnt everything in him, like a fire in a barrel. There wasn't London, there wasn't the war, there wasn't Sherlock, there wasn't John. There was only fire, and a single, last burst inside him, like that spinning, consuming fire in the barrel had hit a chestnut and there was a memory. John was eight and holding a sparrow, it was dying in his hands and he thought, (black coat flapping in front of him, Welcome to London? Laughter. Haven't laughed like that for a while, feels so) I want to be a doctor.

When he opened his eyes again everything hurt a lot and he found that he was not erased at all. He was instead incredibly sore; every cell of his body was like a pinprick of fire. He was laying on a rooftop. In those quick first breaths of aftermath he didn't know what had happened, but he knew that there was danger and that he wanted to be a doctor. He was a doctor. He named all the bones in the human body and the chambers and arteries of the heart and the systems of the body one after the other. He knew how to set a broken leg and how to stop internal hemorrhaging. A relief swept over him so strong that he almost started weeping.

He was on a rooftop, when he rolled over to lift himself up he found that he was a great deal smaller than he remembered. Also dry, which was an improvement. This was distressing, but not as distressing as peering above the edge of the roof and seeing Sherlock pant after a cab. Because John remembered this night. He remembered how easy it was to run without a flack and gear on. How free. He remembered thinking that Sherlock was absolutely mad. Amazing, but definitely mad.

He remembered the feel of stairs and iron and gravel and road beneath his feet.

He remembered the taste of the pasta, the richness of the sauce, the burst of spices, the awkward dinner conversation.

But on this night he remembered so well, Sherlock was alone.

John lay on his back carefully, like he had been shot but didn't know where yet. Like he had been picked up in a bomb blast and wasn't sure he was still all in one piece. His Browning dug into his spine now that it didn't fit as intimately as a hand in the small of his back, then he really did start to cry.

It took a long time for him to remember everything about this night, he was so miserable. Curled up in a pathetic little ball, weeping his pathetic little eyes out, but he finally did.

He propped himself up on a chair to give him some height. Didn't want it to be too obvious.

His hands didn't shake.

Sherlock was still his best friend.

Power of Deduction:
Crack shot, nerves of steel. Strong moral character. Military man, likely Iraq or Afghanistan, skilled at infiltration. Possibly special forces. Tall.