She's born a white pawn. Everyone is, but she enters her first game before she can grow into something more and she gets stuck.

City kids almost always get stuck. Too many people: too many marks seeking each other out to draw a full board. Too easy to get pulled into a game, and too easy to be replaced if they're not up to snuff.

Then they go bad and turn into blacks and they're stuck playing again and again till their numbers grow like sewer rats. Again and again until they're out – but they can't get out as pawns.