Who is Uncle John from Mrs. Mike the Story of Katherine Mary Flannigan and what is their importance?

Uncle John Kennedy is Katherine's uncle, her mother's brother, whom Katherine goes to visit. Uncle John indirectly introduces Katherine to love. First, Katherine meets Sergeant Mike at her uncle's ranch. Second, her uncle tells the story about why he tolerates the behavior of Johnny Flaherty's drinking binges. There is a bond between the men who served in the war together. Johnny is also a terrific cook.