ALERT! I love this Book!! "Enclave" by Ann Aguirre 2011
"In Deuce’s world, people earn the right to a name only if they survive their first fifteen years. By that point, each unnamed ‘brat’ has trained into one of three groups–Breeders, Builders, or Hunters, identifiable by the number of scars they bear on their arms. Deuce has wanted to be a Huntress for as long as she can remember.
As a Huntress, her purpose is clear—to brave the dangerous tunnels outside the enclave and bring back meat to feed the group while evading ferocious monsters known as Freaks. She’s worked toward this goal her whole life, and nothing’s going to stop her, not even a beautiful, brooding Hunter named Fade. When the mysterious boy becomes her partner, Deuce’s troubles are just beginning.
Down below, deviation from the rules is punished swiftly and harshly, and Fade doesn’t like following orders. At first she thinks he’s crazy, but as death stalks their sanctuary, and it becomes clear the elders don’t always know best, Deuce wonders if Fade might be telling the truth. Her partner confuses her; she’s never known a boy like him before, as prone to touching her gently as using his knives with feral grace.
As Deuce’s perception shifts, so does the balance in the constant battle for survival. The mindless Freaks, once considered a threat only due to their sheer numbers, show signs of cunning and strategy… but the elders refuse to heed any warnings. Despite imminent disaster, the enclave puts their faith in strictures and sacrifice instead. No matter how she tries, Deuce cannot stem the dark tide that carries her far from the only world she’s ever known."
I think this book would be a great movie!