One possible theme could be environmental change. If the octopus city is in an aquatic environment, changes in the water quality or temperature could be a major theme.
Well, I'm not very familiar with the specific 'octopus city blues story'. It could be a really unique and creative story. Maybe it's set in a city where octopuses play a significant role, perhaps in a post - apocalyptic or a very strange and magical world.
I'm not sure specifically as I haven't read the exact story, but likely there are characters who are either native to the emerald city or have come to the city with certain hopes and dreams.
The main theme could be about the melancholy or blues associated with the emerald city. Maybe it's about the characters' unfulfilled dreams or their sense of alienation in that city.
Well, it could be about the history and the secrets hidden within the old city. The 'blues' part might imply a sense of melancholy or the hardships faced by the people there. It might also involve some kind of mystery or adventure that unfolds in the alleys and old buildings of the city.
Since I don't know the author or the details of 'Windy City Blues', I can't say who the main character is. It could be a detective, a musician, or just an ordinary person living in the windy city, depending on the genre of the novel.
I don't know for sure since I haven't read it. But they could be typical characters like a detective trying to solve a crime in the old city, or a local artist who is inspired by the city's charm yet also frustrated by its problems.
I'm not sure exactly as I haven't read it in full, but there might be some characters who are leaders in the Slab City community. They could be the ones who try to bring order or some sense of normalcy.