He follows John Winchester to the cemetery in Eureka, California where John and Jacob were searching for a Black Shuck. Hunter watches as Jacob is killed and then saves John. He takes John under his wing and becomes John’s trainer in the art of hunting.
Hunter is known to the crowd at Harvelle’s Roadhouse where the supernatural is a way of life. It’s a gathering spot for the hunters to rest and share information.
He is responsible for taking John on his second hunt with Ichi which leads to John’s first kill, a shapeshifting creature.
The Hunter later reveals himself to be the master of the Helldog they’ve been chasing, and not really a human, just something that inhabits the body of a former hunter.