Title: One Good Man

Setting: The closing moments of "A Study in Pink."

Disclaimer: I do not own Sherlock. The characters in this story are the products of Steven Moffat, the BBC, and the formidable Sir Arthur Conan Doyle.

Detective Inspector Lestrade knew in his bones that John Watson had killed the cabbie. As soon as he noticed the good doctor hovering unobtrusively behind the crime scene tape, with that oh-so-innocent expression of mild curiosity, he knew. Lestrade was surprised and inwardly amused that it took Sherlock so long to work it out, but it was definitely worth it to see the look of dawning comprehension on the face of the arrogant and smug consulting detective. Sherlock was always so sure he knew everything before anyone else did; maybe he actually was in shock after all. (Besides, some of the guys actually did get photographs of him in the bright orange shock blanket. Lestrade had actually sneaked one with his mobile to save as future blackmail material.) But, more to the point, Lestrade also knew something else: it would be utterly futile to pursue Watson in the cabbie's death.

First, the cabbie was, in fact, a serial killer, and a source of embarrassment for the Chief Constable in the media. Many people would be more than happy to see the end of the incident and leave it at that. (Lestrade, for his own part, was relieved not to deal with the court case, anyway, especially since by Sherlock's own admission the shooting was more than justified at the time.) It wasn't as if there weren't piles of other cases waiting for him in his office, either.

Second, the only physical evidence was the bullet that the forensics team had dug out of the wall, and it was mangled beyond recognition after passing through a window and the cabbie before burying itself in the far wall. There was no way to match it to a murder weapon even if they found one.

Third, even if there was any further evidence to be found, Sherlock, now that he realized that his flatmate had saved his life, would use his considerable powers to hinder any sort of prosecution. (This was in itself an oddity. Who would have thought that the two men, so vastly different from each other, would bond to such a degree so quickly? Lestrade dared to hope that Watson might... no!)

Fourth, no one who met Dr. Watson in passing would think that such an unassuming, mild-mannered, even diffident man to be such a crack shot. DS Donovan, for instance, would definitely laugh at the suggestion. But Lestrade knew better. Despite any insults Sherlock threw his way, Lestrade was a keen observer in his own right; he'd seen Watson concealing the powder burns on his fingers. "History of military service," Sherlock had said, and Lestrade didn't doubt it one bit, especially now that he was looking past the modest facade the doctor projected. He certainly managed to disappear into the woodwork, with that unremarkable face and bland jumper. But the way Sherlock defended him, even asking his opinion! The DI couldn't think of any time that Sherlock had actually asked anyone else's opinion, on anything. Lestrade should have seen it at the crime scene the first time they met, but he was too preoccupied with the case. As soon as he got back to the Yard, he was going to run a thorough background check on the good doctor.

Finally, Lestrade had no desire to arrest Watson, anyway. According to instincts honed by twenty years with the Met, the doctor was a good and decent bloke who was looking out for a man who, despite (or maybe because of) his undeniable brilliance, definitely needed someone to look out for him.

As Lestrade watched the pair leave together, he saw them exchange words with Sherlock's brother, who had just pulled up in his usual melodramatic manner. From Watson's change in body language, he could tell that he had met Mycroft already - the man had a remarkable knack for intimidation. Lestrade had had the dubious pleasure himself several times since he began associating with Sherlock, and each encounter with Mycroft had left him undecided on whether to arrest him, pummel him, or run screaming in the opposite direction. Surprisingly (Or not, perhaps, Lestrade mused), Mycroft hadn't managed to scare Watson away, because after a few moments, Sherlock and his flatmate took off again side-by-side.

Amazing.

Chuckling softly, the veteran detective inspector pondered how fate had delivered this ordinary-extraordinary doctor into Sherlock's life. Had it only been a day or so? Lestrade prayed deep down inside that it was a sign for the better. If John Watson could help Sherlock, it was well worth it in his book. Maybe, just maybe, one good man could make all the difference.