Who is Drew Dix, Special Forces Sargeant Dix from Rogue Warrior and what is their importance?

Drew Dix is a Special Forces Sergeant on loan to the CORDS local pacification program in Chau Doc. Drew works with the Nungs, who are Chinese mercenary forces. He is willing to give intelligence and help Richard when Richard shows up in Chau Doc, unlike the official U.S. local commander.