4 ideas
A group of Martian teenagers, including the dancer Luoying, granddaughter of Mars's consul Hans, spend five formative years on Earth as a goodwill delegation meant to ease relations after the war. When they return, they can no longer accept Mars's assigned, archived way of life, and they were never Earthlings either. Their split is a concrete case of people formed by two rival systems who can live comfortably in neither.
On Mars, each citizen registers with an atelier, a state-supported workshop, which provides their livelihood and defines their social place. Every creative and technical work goes into a shared public archive instead of being sold. This removes market precarity, but it ties who you are to an institutional slot that is hard to leave, so security and fixity arrive as one package.
Earth offers freedom of choice and movement, but only through the market, so people must constantly package and sell themselves to survive. Mars frees people from that commercial pressure by guaranteeing their needs, but it fixes their role and makes their lives transparent to the collective. Neither world is simply freer; each removes one kind of unfreedom by imposing another.
Someone raised partly in a foreign system comes home and finds its norms strange instead of natural. That estrangement exposes assumptions that insiders on both sides cannot see. Being dislocated becomes a way of knowing: the person who belongs nowhere is the one able to compare the two worlds honestly.