Just found this fanfic, Never Look Back. It’s a crossover between Neil Gaiman’s short story A Study in Emerald (full version, PDF) and Sherlock, the BBC tv series which sets the Sherlock Holmes stories in modern Britain. A Study in Emerald is itself a crossover fanfiction between the classic Sherlock Holmes series and H.P. Lovecraft. So basically the fanfic updates Gaiman’s story to the modern world. Read it. It are good.
Seriously, I’m not into slash but I’ll make an exception for the fic (that, and the slash parts are easily skippable). I’m green with envy at the prose.