"‘Sour' was written towards the tail end of our time in the studio. We initially had a slightly different instrumental track that we just couldn't quite get to work with anything vocally. We re-worked the instrumental with our producer Jack, and the vocals flowed really quickly within a day or two after that! The chorus in particular came together in an hour or so. The song is about seeing someone bottle up their negative feelings and dissociating, rather than talking it out, and getting stuck in a cycle." (Caitlin Henry)