Origin: Goodwin pretended to be a survivor of Oceanic Flight 815.
Since Then: Goodwin ran out of the jungle and called for help, shouting that there was a man in a tree. Ana followed Goodwin and helped Bernard to safety. Ana took a leadership role, supported by Goodwin. The two seemed to share a budding romance, until Nathan's death and Bernard's discovery of a radio. Goodwin volunteered to trek to higher ground to help get a signal for the radio, and Ana followed. The two had a conversation, and Ana exposed Goodwin as a spy for the Others. She subsequently killed him, impaling him on a spear as the two rolled down a hill fighting.
Origin: Sometime after Juliet arrived on the island, she struck up a friendship with Goodwin, who provided her with some solace as she's prevented from leaving the island.
Since Then: Juliet found out that Goodwin was married to the Others' psychiatrist, Harper. Goodwin and Juliet embarked on an affair despite this, and when Harper tried to warn Juliet about the consequences Juliet mistook Harper's concern as nothing more than jealousy. When Flight 815 crashed, Ben sent Goodwin out to infiltrate the Tailies, where he ended up getting killed by Ana Lucia. When Ben showed Juliet Goodwin's dead body she was devastated.