''The Ghost Map'', by MadameGiry25, is an AU to the events of the Sherlock Holmes short stories "The Final Problem" and "The Adventure of the Empty House". The FF.N summary is as follows: Over his lifetime, Sherlock Holmes has likely encountered more sinister crimes than there are stars in the sky. But now, it seems that he pales in comparison to this new microbial killer that threatens to destroy London forever.Dr. Watson helps to bring the spread of the dreaded cholera to the attention of Sherlock Holmes. When the disease breaks out into an epidemic, Holmes investigates, believing the whole thing to be spearheaded by a mastermind. Then... it gets personal.
Ironic Echo: Moran confronts Holmes in Camden House, where Lestrade arrested Moran some time ago - this time, the game is Moran's. Holmes acknowledges the irony.
It's Personal: When Wiggins dies of cholera, Holmes bows out of the investigation, saying that he wants to speak with the criminal responsible once the police have found him. The narration even comes close to invoking this trope, following up with: And no one should be able to harm the ones who were closest to him. Not without paying for it with their own life.