(I am working on Michael Dibdin's "The Last Sherlock Holmes Story" from Holmes's pov but . . . I'm so sorry – I lost the email and can't remember who reqeusted it! Would you be so kind as to remind me so I can give credit?)
Mrs. Hudson gave a scream that would have been the envy of Ellen Terry or Sarah Bernhardt. Then her hands were buried in her face to smother violent sobs. Holmes moved to comfort her but stopped suddenly when he heard the masculine tread on the step.
It was like looking into a mirror – a twisted mirror with strange, deliberate mistakes. This other version of himself was too short and not quite thin enough. The hair color was a shade too light, the complexion a shade too warm, the eyes too blue. The hand that grasped the banister was too square, too quick to show its strength. The shape of the face was all wrong for a Holmes.
Of course, it was no longer quite Watson's either, though that was who the man was. Watson – attempting to look like Sherlock Holmes.
The voice had changed too, he noted, more ringing and clipped. It was not the voice of Sherlock Holmes but neither was it the voice of Dr. John Watson. At least, not the Watson he had left three years ago.
He could only imagine what forces in his friend's life would have pushed the doctor to metamorphosize into the detective. And then he decided he did not want to imagine. Whatever they were, they had been powerful enough to chip away at Watson's sanity that not even a bloody war or their most eldritch of cases had.
Both men knew full well there could be only one Sherlock Holmes alive in the world. The former version had returned. It remained to be seen if the new one could revert or if the Watson of old was lost forever. Looking at the strange glint in his friend's newly strange eyes, Holmes found himself inclined to fear it was the latter.