Who is Pat from Junky and what is their importance?

Pat is a junky and drug dealer in New Orleans. Bill meets him in a gay bar and describes him as having a peasant face. Pat is Irish, intuitive, and shrewd malice. He supplies heroin to Bill who nearly overdoses, and then regularly supplies him for several weeks. Eventually Pat and Bill form a partnership to buy and resell drugs. They are arrested together, and Pat spends a brief period in jail and then returns to drug use. Pat remains in New Orleans while Bill moves to Texas and, later, Mexico.