Disclaimer: I own my words and my ideas, but not the characters or premise, which belong to the BBC and Sir Arthur Conan Doyle.

A/N: So this just sort of occurred to me while reading some Sherlock fanfiction or another (I believe it was Anything But Elementary by xox-hattii-xox, which is an excellent work which you should read), though the idea itself had little to do with that story. Sally Donovan's comment about Sherlock's inevitable graduation to murder at some point popped into my head, and I went, "Sherlock wouldn't kill someone. Where's the challenge in that?" Aaaaaand this is what came out of that thought. It's probably a little out of character, and it ends rather abruptly because I didn't want to get into the case itself.

Hope you enjoy!

Crime

"I tell you, one day we'll find a body and Sherlock will be the one to have put it there."

While Sherlock ignored the comment, as he always did, John had finally had enough. He rounded on Sally, face set in a steely expression that had likely served him well as a soldier and was certainly enough to shut up one member of the police.

"Do you think," he ground out, tone clipped and angry, "for one second, that if Sherlock were to kill someone, you'd ever know it?"

The room fell silent. While they'd come to expect John Watson to defend Sherlock, this was not the usual sort of defense. Even Sherlock seemed slightly taken aback.

"Sorry?" Sally, aware of the eyes on her, shifted uncomfortably.

"Do you think that if Sherlock Holmes decided to kill someone, you would ever even suspect him, let alone know what he'd done?" John's tone had turned vaguely mocking, and he exaggerated every word as though speaking to a child. "He is possibly, no, probably the smartest man in London, if not the country, and he studies criminal behavior for fun. If he wanted to commit a murder, he would do so in such a way that nobody would be able to link it back to him, even in the slightest. In fact, he'd probably end up helping you solve the case, though of course he'd have framed someone else for it, and his arguments would be so airtight that nobody would have a hint of doubt that he was correct, just as with every other case he solves for you. Either that, or there would be no case to solve, because the person would simply vanish for a perfectly valid reason and there'd be no hint of foul play."

"John... perhaps this isn't the best...?" Sherlock trailed off, looking unsure as to the optimal course of action. While he appreciated the compliment, as he did all of John's compliments on his brilliance, this was a little strange, even for him.

"And furthermore," John continued, ignoring Sherlock completely, "why would he choose to kill anyone? He 'gets off,' as you so charmingly put it, on solving crimes. He thrives on the challenge of it. There is no challenge in getting away with murder. People do it all the time, for reasons other than intelligence or planning. They get off on technicalities or sympathetic judges or ambiguity in the evidence. It's actually rather easy to get away with murder these days. So why would Sherlock kill someone when it's harder to find a murderer than be one?"

By now, one could have heard a pin drop in the silence. John, apparently done with his speech, turned back to Sherlock and raised an eyebrow. "Are you going to be finished examining the scene before I'm due at the surgery, or should I call in sick."

"Call in sick," was the murmured response.

"Excellent. Excuse me." And with that, he left the room, fishing his mobile out of his pocket as he did so.

"What was that?" Sally, like everyone else, looked vaguely shell-shocked.

"That, Sergeant Donovan, was the truth." Surprisingly, it was Lestrade who answered the question. "No need for you to continue insulting someone who is here at our own request, and who is responsible for solving more cases than you are, however much he grates on our nerves while doing so."

"But..."

"That's enough, Sergeant. Sherlock? Any thoughts?"

"The mother did it." When all he received was a blank stare, he frowned. "Must I explain everything to you?"

And they were back to what passed for normal.