Books Of Change

Author at https://www.fanfiction.net/u/275758/Books-of-Change.

A Study in Magic (Harry Potter/Sherlock)

Reviewed by Kathryn Andersen on 8th April 2015 (2)
Tags: Long Novel, Crossover, Family, Adoption, Genderbending, Worldbuilding, AU Divergent Timeline, First Year, Second Year, Third Year, Fourth Year
Characters: Harry Potter, Sherlock Holmes, John Watson, Ron Weasley, Hermione Granger, Neville Longbottom, Albus Dumbledore, Remus Lupin, Sirius Black
(1223K, 492408 words)

Summary: When Professor McGonagall went to visit Harry Watson, son of Mr. Sherlock Holmes and Dr. Watson, to deliver his Hogwarts letter, she was in the mindset of performing a familiar if stressful annual routine. Consequently she was unprepared for the shock of finding the cause behind Harry Potter's disappearance. BBC Sherlock HP crossover AU

Brilliant. Characterisation, world-building, mysteries, deductions, clever plans, relationships, character growth, mistakes, consequences, they're all there, and all well done. This is an epic because it covers Harry's first four years at Hogwarts; you might want to take a breather in between each year... except that you won't want to, because this will drag you in and not let you go.