This novel depicts a search for truth and identity. Because the German soldier is a prisoner, trapped in a community where he does not actually belong, our protagonist finds a companion in him. This means that she feels like a prisoner trapped in her own community, and like the German soldier, her friends and family use some information about her to prevent themselves from learn more about her. They feel they have enough knowledge to understand her, but she experiences this as injustice.
It is unjust, she feels, in the same way as his predicament. After the war (WWII), this German soldier was assumed to be a Nazi sympathizer, but as he explains, neither he nor any in his family ever supported Adolf Hitler. They were merely fighting for Germany, their home, which was left in a state of permanent disarray by the horrible trade restrictions imposed after the Great War. So, if Patty simply tries to see what of his experience reminds her of herself, we can assume she finds a lot to commiserate with.
So, perhaps she feels like a traitor to her family just by being herself. Her family and friends can be so closed-minded, and it's basically a defense mechanism, from what she can tell, but they always tell her that she is their enemy, just like they tell the German that he must be a Nazi supporter, just because they're scared and traumatized by WWII. Without real reasons to hold him as a Nazi supporter, we see the true problem; the community is paranoid, and Patty is being chronically disenfranchised as tensions rise, which is untimely, because she is trying to break through into her full identity. The war has harmed her, and she didn't even know it.
