The forgotten test
The first major symbol is that the information that Cia knew from her testing has been erased from her memory. This is a symbol for mind control, because the government is able to control the narrative she believes about her own life by selectively removing her memories of mistreatment. Perhaps this is a sophisticated symbol for propaganda, which is when the government attempts to manipulate the cultural narrative among the populace.
Obadiah's body
Cia sees Obadiah's body after his "redirection," and she realizes that redirection just means execution. This is a symbol in the book about the stakes of the government conspiracy facing her. She wants to escape, but then is met by someone who "redirects" her feelings in a productive way. Therefore, Obadiah's death is symbolic and archetypal, because it shatters her innocence and serves as her inciting incident.
The resistance
The resistance represents the hope for change through combined forces with a willingness to sacrifice. When the team cooperates, they do so understanding that if they are caught, they will certainly be executed, so the hope for their society rests upon their willingness to lay their own lives down for the hope of change. This is a symbol for self-sacrifice, and it is a symbol for heroism, because it takes a hero to make such a decision.
Conspiracy and paranoia
Through motif, the reader sees that there are plot twists afoot. There is no reason to trust anyone in the novel, because the conspiracy is clearly detailed and complex. For instance, the memory wipe, the state sanctioned murder, the abuse of the populace—they are all indications that the government is willing to meddle, so the tone of the novel is paranoid, because the government could have hidden methods. The characters struggle to guess how much the government knows about their movement.
The fake rebellion
When the rebellion is seen as part of the government conspiracy, that inverts the symbolism of the resistance movement. Because the government expected a social uprising, they created one themselves and allowed disenfranchised people to participate in it so that they could easily eliminate unwanted members of their society. The symbol is dark and ominous. It symbolizes absolutism and domination, because the hope that Cia needed to believe in was itself part of the conspiracy.