Sherlock calls it his mind palace, but there are days when it feels more like a train with no driver heading down a hill at full speed with no end in sight and as it runs more thoughts occur and more trains branch out and out and away, left and right, until there are a dozen, a hundred, a thousand, a thousand million trains all racing in different directions; he can't stop any of them because all of them are leading somewhere (and why should he want to stop them they're helping him get to the conclusion, the answer, the ever elusive key that will make them all make sense but until then they race, gathering details to fill their furnaces like coal, fueling them faster and faster until there's nothing left to do but ride them to their inevitable end) as suddenly the blunt force head wound matches the pan on the stove; the wine in the glass matches the stains on the wall; ligature mark matches the twine from the parcel in the front hall—and all these things line up and form a single, coherent picture and no one else notices these things because they are all idiots—and the parcel came from a company which is an obvious front for an embezzling scam and…

John.

"Sherlock, breathe."