Antonym

Lorne is a Mask.
Aixela is a Face.

Lorne has every single thing provided to him. He's moderately intelligent, obedient in any way that matters, and in a way able to be controlled. The main thing that sets him into the Masks is his beauty. Beauty is the ruling qualification in this 'perfect world.' He doesn't spend much time thinking or pondering his life. For what is there to think about when you have everything?
The definition of each Mask could be almost the same, because no one is unique. If everyone is the same, an empty obedient shell that thinks they are living a perfect life, then is it really a perfect society?

Aixela struggles just to survive. The Faces live in a world that is prejudiced against them. Because they are not smart enough, obedient enough, polite enough, and most of all pretty enough. The Faces just want to be treated as equals, they want someone to do something about the injustice. Riots and uprisings flood the streets of The Other Side.
Aixela is someone. She's a rebellious girl who feeds the uproars, the main reason she isn't a Mask. She borders the line of intelligence and beauty, though fails to meet the requirements of class and obedience.

They have absolutely nothing in common with each other. They live on opposite sides of the Wall and they live lives so drastically different that it seems impossible to think they could ever relate to each other.
Tiny coincidences, big mistakes, and a whole lot of chance brings everything that they believed in spiralling out of control.