Lyman's grandmother, Susan is an artist from the East who marries an engineer and moves West, navigating life in various frontier towns while maintaining a correspondence with her close friend Augusta.

Susan's husband and Lyman’s grandfather, Oliver is a dedicated engineer, whose struggles with failed projects and personal challenges are central to the family history Lyman investigates.

A young woman from the hippie generation, Shelly interacts with Lyman as he explores his family’s past, often challenging his perspectives with her contrasting worldview.

Augusta is Susan's lifelong friend whose correspondence with Susan plays a pivotal role in Lyman's research; Thomas is Augusta's husband and a successful literary editor, representing the life Susan might have had.