Max stands in the kitchen and asks Hans if he still plays the accordion. Then Death brings the story back to World War I, when Hans was fighting in France. He became friends with a Jewish man named Erik Vandenburg, who taught him to play the accordion. One day the sergeant asks for someone who can write well (to write letters for the captain), and Erik volunteers Hans, knowing that the rest of them will be going into battle. In this way Erik saves his life, as all the other men in Hans's company die that day, including Erik himself.
Hans's backstory shows how much has changed in Germany since World War I – at that time Erik, a Jew, fought and died for his country like any other soldier, but at this point under the Third Reich Jews are seen as enemies or subhuman. Hans's actual story again shows the randomness of fate, which Death often points out – why one person should die instead of another. It is also an example of writing and language saving Hans's life.
Hans kept Erik's accordion, as it was too heavy to be sent home. After the war he came to Erik's wife (and young son) and offered his help if she should ever need it. He wanted to return the accordion but she insisted he keep it. Hans left his name and address if she needed a free apartment-painting, but he never expected to see them again.
Hans clearly owes a huge debt to Erik, but he had no way of repaying it at the time. This also gives the backstory of the accordion – for Liesel it is a symbol of comfort and happiness, but for Hans it is a symbol of his debt to Erik Vandenburg.
Time progressed and the Nazi party grew popular, but Hans refused to join because of his debt to Erik Vandenburg. He began to lose customers because he wasn't a party member, so finally he submitted his application. That same day he offered to paint over the words "Jewish filth" on the door of a Jewish man whose shop had been trashed. Hans kept his promise, and then returned to the office and retracted his application to the Nazis. He was then placed on the waiting list, but was generally left alone because of his skill at painting and playing the accordion. Then one day Hans was on his way to a painting job when a man named Walter Krugler approached him and asked if he still played the accordion, and if he would keep his promise to the Vandenburgs.
Simply by remembering his debt to Erik and therefore refusing to persecute Jewish people, Hans has become subversive under the new regime. This is another sign of how the morality of Nazi Germany has been turned upside down – refusing to take away another person's basic humanity is seen as criminal activity. Hans painting over words of abuse is another instance of the physicality of language, but also subverting hateful words through actions of kindness.