Faith Harrington is the main character in the semi-canonical tie-in novel Endangered Species by Cathy Hapka. Her sister is Gayle Harrington, a woman who is often mentioned due to the fact that Faith often remembers her words of wisdom.
Before the crash
As a teenager, Faith lived in an apartment block with her sister Gayle. Early in her life she took care of a neglected dog, nursing it back to health. Faith is obviously a clever woman, having been accepted into one of the toughest PhD programs in the country.
Faith was an environmentalist and reptile expert who studied with Dr. Luis Arreglo. She fell in love with Oscar, and joined an extremist environmental activist group with him against Arreglo. Her romance with Oscar was very rushed. Oscar had asked her to move in with him on their second date. Faith complained that she could never remember her dreams. She was tricked by her boyfriend, Oscar, into letting him come with her to meet her former college professor. Oscar injected snake venom into her professor. Oscar wanted to leave the country with her, start a new life. But she smacked a bucket onto his head, so that she could leave him. Faith was on the run from the police before the crash. Faith was able to purchase a ticket for Flight 815, because someone else cancelled.
On the Island
Soon after the crash, Faith noted that she had blacked out during the crash and had landed in the jungle. She saw a snake, Morelia Viridis soon after she awoke in the jungle glade. In addition, she had ripped her best skirt, her faux-silk blouse was streaked with mud and grime and she had lost her shoes. She had scratches on her arms and an ugly-looking gash on her left shin, but was otherwise alright. She met a stranger in the jungle, and she was clutching a broken arm on her stomach or holding a wound on her torso (in actual fact she had just removed her handcuffs). The stranger's face was smudged with dirt and her forehead was dotted with sweat. She then ran to the beach, and was far away enough to see, but not be hurt by, the turbine explosion. Shortly after, she met George, who convinced her to start collecting luggage. Faith and George saw Boone running around with pens in his hand for Rose. She then witnessed the wing of the plane fall near Jack, Claire, and Hurley. Faith asked Jack about her injury, just to make sure; and was worried that Jack and Kate were laughing at her. Faith went into the jungle with George, Hurley, and Boone to search for more food, when she sees a Paradise Parrot, which has been extinct since the 1920's. She recovered the Backgammon game with Locke and saved George from a snake, which George saw as an offense against his manhood, and shouted at Faith. She later saved him from a snake, called a Death Adder, which are particularly dangerous.