Some links...
Another blog I came across is this one: http://booksofnote.blogspot.com/
What both Jay and Aimee don't know (this is Isabel's ide) is that they were both "bought" illegally by their parents, and were actually the offspring of outsiders. Jay's parents were old when they got together, and his mother couldn't have children. They went to the blackmarket to "buy" Jay (why?), and so did Aimee's parents. (Is it too far-fetched, too Star Wars to say they were brother and sister?) This is why they both feel "different". On this fact hinges one of the major twists of the story - When Jay finally manages to get a DNA test to prove who he is, he is not the person he thought he was, and so cannot be allowed back in to take up his old life, which was based on a stolen chip at the time of his birth.
When Jay meets Aimee again, Aimee is working as a carer, looking after the aged. It is through the stories that they have told her, about their memories of nature, and the world as it was, that make her feel she would like to go outside and experience a different side of life. Even if it's only for a short time. She is restless and doesn't know why, and is suspicious about the way people are locked in the protective bubble of the city and do not get to hear anything about what is outside. She is also looking after her aged father (her mother died two years ago) and her plan is that when he dies, she would like to make a move.