ABBA is a Swedish band that became popular in the 1970s, and even today is still wildly popular—but it’s not something Darius expects to encounter his Iranian grandmother listening to. In fact, learning that Mamou likes ABBA is surprising enough that Darius finally finds his voice and is able to ask Mamou about her life. It’s significant too that this comes after Darius begins to relax around Sohrab: Sohrab’s friendship is showing Darius that being open, curious, and caring isn’t going to end in pain or humiliation.