John Locke was not raised by his biological parents. He was sent from foster home to foster home and didn't know his biological mother and father until his mother found him and scammed him into thinking that he'd found his biological father on his own. His father, Anthony Cooper, befriended him, and then let it slip that he needed a kidney transplant. Locke was quick to offer his kidney, but after the operation, his father didn't want anything to do with him. Locke was obsessed with wanting to know why his father didn't want his friendship.He met Helen and they began a relationship, but she wanted him to stop watching his father. He couldn't do this and Helen left him.
When Locke found out that his father was conning a family, he interceded and his father pushed him out of an eight story window. Locke survived, but was paralyzed from the waist down.
He began working for a box company. He wanted to do a Walkabout tour of the Australian Outback, but when he showed up in a wheelchair, the company said he couldn't go. They sent Locke home on Flight 815.
Island: After the crash, Locke gets sudden use of his legs. He believes that the island has healed him and that he must listen to the island and do what it asks.
At one point he sees something that he later describes as a beautiful white light (Ep: 1x4, Walkabout).
After he and Boone find a hatch in the ground, Locke believes it's his destiny to open it and he is so obsessed that he ends up getting Boone killed after he has Boone climb up a cliff and into a small plane.
Locke and a group get dynamite to blow the hatch open and they find Desmond inside. Locke's new purpose becomes punching in the code and hitting the execute button to reset the timer every 108 minutes.