Austin Reynolds is the son of serial killer Tommy Tolliver.
Austin is a 12 years old boy who lives in Ohio with his mother; he and his father are estranged. He owns a Facebook page, which Sam Winchester used to track his status.
After Cain murders Leon and Tommy, he goes after Austin. Having realized that Cain will be targeting the boy, Sam, Dean and Castiel get Austin to safety before Cain arrives. Once Cain appears, Crowley uses an illusion spell to make it appear as if Austin is still at home and to lure Cain into a devil's trap so that Dean can kill him. Cain is unable to see through the illusion of Austin until after he's inside the devil's trap. Unable to escape, he is forced to fight Dean, who manages to kill him.