A novel, more than likely. It might work interestingly as a comic as well.

Escaping from the orphanage, Mateo and his little sister Seraphina try to survive in a world where the robots have taken over. They discover the resistance and are taken in by them, learning that their parents were once scientists for them and working on a way to get rid of the robots and restore things to the way they once were.

Slowly, Mat discovers some disturbing things about what he is and what power his sister also possesses.

Mateo - A fourteen year old boy with a rebellious spirit and hopes for a brighter future.
Seraphina - Mat's six year old sister, wide eyed and innocent and she looks almost nothing like him.

It's a rubble filled post apocalyptic setting in the destroyed ruins in the city and underground hide outs sort of sense. There are gated communities that are essentially Utopian, but only for the aristocracy while the rest of the people are without work and just trying to survive without breaking any of the arbitrary laws. The law abiding poor live in slums, which is still better than rubble.

I came up with the title first. It was just a title that sprang into my head out of nowhere and I really liked it so I wrote it down and did nothing with it for a while.

Later, I watched Time Stranger. Somehow, watching this made me want to write a post apocalypse universe where small, untrained children try to save the world while running from their own tragic pasts that they can't remember. But then Sera came to mind and she was too adorable to make depressed.

And the little girl wants to go see grassy fields to play! With butterflies!