I love this story beyond my ability to express! Your characterization of Watson and of nineteenth-century England is note perfect. I was wrapped up in the depth of portrayal of both the wizarding and the Muggle worlds, with skilled, intelligent, and dangerous characters in each. The plot was engaging at every point. I adored Watson's outsider POV on the professor and two students, and his journey from astonishment to acceptance of the wonders of the wizarding world. Draco maturing, Harry growing into his power, and Snape as deadly competent are my favorite takes on the characters. And Holmes's solution to the mystery is so absolutely perfectly Holmesian. A masterpiece!
"No," Potter breathed, "I don't expect you to do anything except what you've always done: spit vitriol into my face and protect me with your life."
Probably the best description of Snape and Harry ever written. ♥