Swift then explained to her co-producers Aaron Dessner and Jack Antonoff the role Alwyn played in the creation of Swift's duet with Bon Iver.
"Joe plays piano beautifully. He's always just playing and making things up and kind of creating things. And 'Exile' was crazy because Joe had written that entire piano part," she explains.
"He was singing the Bon Iver part," she adds. "And so I was entranced and asked if we could keep writing that one. It was pretty obvious that it should be a duet."
As part of the film, Swift then played "Exile" with Antonoff on guitar and Dessner on piano. Because of the pandemic, Justin Vernon, aka Bon Iver, appeared from Eau Claire, Wisconsin.
In addition to the documentary, Folklore: The Long Pond Sessions is out now as a deluxe album. Folklore, which spent 8 weeks on top of the Billboard 200 since its release, is also nominated for album of the year at the 2021 Grammys.