Taylor Swift and Aaron Dessner perform "Seven" live in Pittsburgh.

Taylor Swift brought out Aaron Dessner during her Eras Tour in Pittsburgh to perform "Seven" live for the first time. She also performed surprise songs "The Story Of Us," "Mr. Perfectly Fine," and "The Last Time" during the weekend. Dessner previously appeared during the tour in Nashville and is expected to join Swift in his hometown of Cincinnati. Swift praised her dad and talked about growing up in Pennsylvania before launching into "Seven."