In January 1990, Adam's mother met John Winchester in Windom, Minnesota when he came into the hospital where she worked as a nurse, when he was injured during a hunt. Adam was born on September 29, 1990 although he didn't have any contact with John until he was twelve. Thereafter he had sporadic contact with John who taught him pool and poker, took him to ball games on his birthday, bought him his first beer when he was 15 and taught him to drive in the Impala. In 2009 he was studying pre-med at the University of Wisconsin.
Adam and his mother are killed by Ghouls in revenge for the killing of their parent by John Winchester. One of the ghouls took on Adam's form and memories in order to lure John to the town, only to find out that he died. The ghoul then decides to kill Sam and Dean in John's place.
While Dean is initially sceptical and assumes Adam is a supernatural creature, he and Sam come to believe that Adam is human and their brother. Dean is envious of the time John spent with Adam, but when he recognises that John tried to shield Adam from hunting, he clashes with Sam who is keen to train Adam as a hunter.
Dean finds the bodies of Adam and his mother in a crypt, and after killing the ghouls, insists that he is given a hunter's send off in the form of a funeral pyre similar to that given to John by his sons.