Marginny’s husband and Aggie and Cayenne’s father. Frank and Marginny live next door to Penn and Rosie in Seattle, and when they stop by to introduce themselves, Rosie blurts out that Poppy is transgender. Frank and Marginny decide not to tell their kids about Poppy, and their decision kicks off the secrecy of Poppy’s gender in Seattle. Frank is accepting of Poppy’s gender, although he occasionally says insensitive things without thinking. The Grandersons and Poppy’s family have a monthly get together they call “Dueling Dinners,” and they all enjoy a nice and easy friendship.