 The news that Bomer had been cast as Blaine 's brother appeared on January 27 , 2012 . Bomer had suggested to Glee co @-@ creator Ryan Murphy that he consider using Gotye 's song featuring Kimbra , " Somebody That I Used to Know " , as a duet on the show . Murphy had already thought of doing the song , and a week later Bomer received a text from Murphy asking if he " wanted to come on the show to sing it " . Bomer 's scenes as Cooper were shot starting February 13 . In addition , it was reported in early February that there would be a flashback scene featuring Cooper and Blaine when they were children ; young actors were then being cast for the roles . 
