The Compound is a miniature world, ostensibly outfitted with everything the family would need for fifteen years. It is a symbol of Rex’s desire to challenge himself and to test his own theories about existence, survival, and innovation under high-pressure. It also represents his instability and neglect for his family. He treats them as if they are laboratory subjects, and his property.

The Compound is a lie, and the ultimate symbol of the lengths to which Rex will go to deceive his family for his own ambitions. 

Eli lets his hair grow long while he is in the Compound. When he begins fighting against Rex and is determined to get the family out of the Compound, he asks Lexie to shave it off. Previously Lexie had told him that he was just like his father, and Eli has worried that it might be true. The drastic gesture of cutting off his hair comes after he has decided to fight against Rex and free his family at all costs. Eli’s hair was a symbol of his childhood. He wore it long while he let his father take charge of the situation. By cutting it, he asserts his own agency and begins to experience a new identity; he is no longer just Eddy’s twin, or merely a guilt-stricken boy trapped in the Compound.