Barry Cook was in Sam's homeroom class in Truman High, and was Sam's friend.
Barry is a smart kid and has planned his future out. He desperately wants to get far away from high school, and he tells himself this to help him get through the day. Barry meets Sam, and when Sam accidentally drops his butterfly knife, Barry is amazed Sam has one. He later introduces himself to Sam.
During class, Dirk begins to bully Barry, and Sam tells Dirk to stop. They become friends when Sam help Barry pick up his books. Barry tells Sam of his plan to go to Michigan State to become a vet. When Dirk later tries to fight Sam, Barry runs to get a teacher and comes back with Mr. Wyatt. Sam continues to protect Barry up until he has to leave. As Sam leaves, Barry waves goodbye to him.
A year later, Barry slits his wrists in the school washroom. When Sam learns of this years later, he feels immense guilt, saying that if he'd stayed at the school maybe he could've helped Barry. However, Dean doesn't believe this to be the case, saying that Barry was on every anti-anxiety and anti-depressant known to man and his parents had just split up. When a ghost haunted Barry's old school, Sam and Dean believed he was the ghost as he was the only violent death on the property and burned his bones, causing Sam even more guilt as Barry was his friend.