The author says that this is “what happens if, instead of making them wait twenty years, I give them everything they need to fix themselves right now?”
Sherlock is orphaned at 11 and Mycroft is responsible for him. He hires Mrs. Hudson to help care for him and then six years later John Watson and Greg Lestrade come into their lives. The plot has a great mix of elements from canon and series one of Sherlock.
This was another one of Issen4’s excellent recommendations! It’s 43 chapters long and sucked me in until I didn’t want to do anything else but read it.