Jack is a successful spinal surgeon. He works at the same hospital where his father, Christian Shephard, works. Jack became a doctor in an attempt to receive acceptance from his father that never comes.
Jack has no children; although he was once married to a woman he operated on. She was considered a lost cause, but Jack saved her life. They divorced because he worked too much.
Jack went to Sydney in search of his alcoholic father. His father lost his license after Jack reported him to the hospital board for drinking before a surgery where a patient died. Jack arrives in Sydney only to find his father dead.
Jack books passage on Oceanic Flight 815 to bring his father’s body home.
LOST starts with Jack’s eye opening to see a beautiful blue sky. He wakes to find total chaos and that the plane has crashed. He goes in to doctor mode trying to help any he can.
Jack is appointed the leader of the survivors, a bit unwillingly. His sole mission is to ensure that they all find a way home.
Jack ends up becoming one of the Oceanic 6 (the only six to successfully leave the island). He makes a home with Kate and Aaron, but sabotages himself. He drowns himself in alcohol and pills trying to forget the need to return to the island. After three years, he is finally given the chance to return and does.
Jack is sent back to the 1970s when he gets to the island. He takes Faraday’s advice and sets off a hydrogen bomb in hopes of destroying the island and returning to the “real world”. In the process, Juliette is killed, which causes him to doubt himself. He returns to the current time, but is still on the island.
After much thought and a near death experience, Jack gets his “mojo” back and becomes Jacob’s replacement. This only lasts long enough to destroy the man in black and save the island.
LOST ends with Jack lying in the same bamboo field were we first saw him. This time his eye closes as he dies.
He was able to accomplish what he set out to do. He saved his friends, returned them home and saved the island.
In the flashsideways, Jack is able to reunite with Kate and all of his friends. He is able to move on, finally let go and allow himself to be happy.