Spoilers: post The End of Time, non-canon
"Before Harry met Lucy" is part of a series called “A Timelord and his Madman”, but can be read as a stand-alone. The series include: (1) His Silent Mind, starting from the events of the End of Time, but with an alternative twist that the 10th Doctor was not forced to regenerate. (2) Judoon Justice. (3) A Murderous Feast. (4) Shattered Worlds. The links to these stories can be found on FF account author's page, or go to my WEBSITE for more information.
Genre: drama, romance
Characters: The 10th Doctor, The Master (John Simm), Lucy Saxon, River Song.
Synopsis: The Master travels with the Doctor back to the Christmas of 2004 before Harold Saxon had ever met Lucy. A sinister creature escapes from a 18th century painting and threatens the life of his future wife. Will the Master succeed in rescuing her without affecting his own future?
Chapter 1 is HERE
Chapter 2 is HERE
Chapter 3 is HERE
Chapter 4 is HERE
Final Chapter 5 is HERE