Back in November 2020, Swift revealed the identity of her mystery Folklore co-writer William Bowery, which was revealed to be her boyfriend and actor Joe Alwyn. Bowery continued to gain co-writinng credits on her December album Evermore, on the tracks "champagne problems", "coney island" featuring The National and Bon Iver collaboration "evermore", and in a new interview with Vulture, Alwyn spoke about working with Swift on the tracks.

Alwyn revealed that he was "messing around" on the piano and was singing what would become the first verse to Folklore track "exile" when Swift asked him to help her finish the song. Alwyn said, "It was completely off the cuff, an accident. She said, ‘Can we try and sit down and get to the end together?’ And so we did. It was as basic as some people made sourdough."

When asked how he managed to unintentionally write a verse for a Swift song, Alwyn responded, "Who doesn’t walk around the house singing?"

According to the piece, Alwyn had been listening to The National, and ended up writing the chorus for "betty", "I’d probably had a drink and was just stumbling around the house," Alwyn explained. "We couldn’t decide on a film to watch that night, and she was like, ‘Do you want to try and finish writing that song you were singing earlier?’ And so we got a guitar and did that."

Read the full interview on Last week Taylor Swift released "This Love (Taylor's Version)".