The Train Station
The novel is mostly set in a train station where Hugo lives as a playful street urchin. Although to the adults, the large building is obviously a business, with very serious rules and order, Hugo sees the Train Station as a game. This leads to cat and mouse stories through the station, describing the station, the trains, the various businesses, the many people who pass through—all reminders to the reader that in lieu of a home and a family, the whole world has become Hugo's home and family, whether they feel the same way about him or not.
Images of fun, play, and magic
Just because Hugo has been deeply hurt by life, that doesn't mean his boyish appetite for fun has gone away. He loves to make everything into a game, and when he feels lonely, he bothers an adult and steals something so they chase him (a common boyhood game). Eventually, his appetite for joy shows him that Georges is not who he seems. He is a magician, a hero, and he ends up being Hugo's hope at a happy, healthy life. Hugo has been saved by his perception, because he sees everything as a game, which helps him to win, even in dire situations. The titular Invention itself is an image of this kind.
The movie imagery
Many movies appear in the novel, both when the toy begins to work, and also later, when Hugo and Georges watch movies together. Originally, Georges is averse to movie imagery. When they start the film, he gets startled by the projector's lights and sounds. He doesn't want to look at his films. He has fans, because he is a famous filmmaker, so his aversion to film is curious. It seems to signal trauma, which means that for Hugo, movies represent fun, but to Georges, they represent destiny and fate.
Images of poverty
The uncle serves as a reminder about why Hugo prefers his life as a homeless kid. The abusive drunkard dies, a sign of his inability to take care of himself. Then there are the pictures of poverty that the boy himself tells. He lives as a homeless person without resources or possessions, without a place to live, exposed to the public who tends to openly resent him. These are pictures of life on the bottom tier of the social spectrum. Instead of seeing his need and helping, people tend to be annoyed by Hugo.
