Jim Gallien is the man that meets Alex when he is ready to embark on the final leg of his long journey to find whatever it is he thinks he would find "in the wild." As Alex walks along the road in Alaska trying to find his way to a spot he's chosen along "the Stampede Trail," Jim offers to give him a ride.
He also points out some of the inadequacies in Alex's plan and tries pretty hard to convince him to go back to Anchorage in order to get some of the supplies and gear that Jim knows he will need. He even goes so far as to try and tell Alex that he really is doing something foolish but obviously Alex wasn't willing to hear it.
So Jim brings him to the closest point he can along the road and drops him off, forcing him to at least take a pair of boots that Jim had in the bed of the truck. Jim is the last person to see Alex alive as he moves off down the trail.