The Youngest Holmes

When a mysterious young woman who appears to have the same brains as Sherlock moves into 221A (the flat above Sherlock and John) you can only imagine how interested Sherlock, Mycroft, and John become in this girl. But imagine how Mycroft and Sherlock will react when they discover that she was hidden from their knowledge by their parents after she was born and became the youngest Holmes. (SPOILERS FOR SEASONS 1-4)

DISCLAIMER: I do not own any of these characters or places, including: Sherlock Holmes, John Watson, Mycroft Holmes, Mrs. Hudson, 221B Baker Street, and I will be adding things as the characters and places are added. I do however own the storyline of the sister in this story, not the cases, however. I also own the character of Aurelia Holmes. (Also, some of these parts will be different from the tv show, because of where I'm going with the story during the chapters