People would go and kidnap people for slaves to make money and so they kidnap the children because for some reason it's easier, it's a good thing we don't have slaves today, everybody are equal to each other.
sometimes they will forge a rebellion and try to take the ship, sometimes they win, other times they don't.
If they don't win they get punished and sold to people who have no regard for helpless children and willing to put them to work. If they do win then they steer the ship back to their home and boom FREEDOM! *angel singing* the good ending.