8. "Somebody I Used To Know" And Blaine/Cooper interaction. Everyone was thrilled to hear Matt Bomer was cast to play Blaine's big brother. Their relationship wasn't picture perfect like people would have assumed. All of the awkwardness came to a head when they performed "Somebody I Used To Know". Normally we would look at that song as a love song, but Glee went a whole new direction with it and made it reflect a familial relationship which was really amazing.