In Taylor Swift's “august” love-triangle story, James is 17 years old. The song presents a fictional teenage romance involving James, Betty, and the unnamed narrator associated with August.
“august” is told from the perspective of a girl who falls for James during a brief summer relationship. James is already connected to Betty, and the story eventually leads him back to Betty after the summer ends.
The age detail places the song’s emotional world firmly in adolescence. It also helps distinguish the fictional narrative from Swift’s autobiographical songwriting, since Folklore deliberately created imagined characters and story arcs.