The closing track of Hit Me Hard and Soft, "Blue" is a sprawling, six-minute exploration of acceptance as Billie Eilish wrestles with understanding an ex-lover's troubled past, acknowledging they're unlikely to change.

"Blue" is actually a Frankenstein's monster of two previously written songs: "True Blue" and "Born Blue."

"True Blue" dates back to Eilish's early days, penned alongside her brother Finneas around the time of "Ocean Eyes." It never saw the light of day at the time, but a 2022 leak inspired Eilish to work on it again. "We brought back this song that we made when I was 14 and Finneas was 18 called "True Blue," Eilish told The Sydney morning Herald. "We brought it back and we changed it a bunch, but we kept the hook." The reworked "True Blue" gets a fresh coat of paint with a new verse that references every track on Hit Me Hard and Soft (except "The Diner" – that one's from a different perspective, right?). This isn't the first time Eilish has played with interconnectivity within an album. "Goodbye," the closing track of her debut project, and "NDA" from her sophomore record both reference songs from their respective albums.