Heres a story I've put together:
Earth is dying. After decades of disease and plauges, global warming and pollution, the Earth has finally gave in. With it, it takes it's former inhabitants; human beings. These being the most treasured sport for Predators, they are forced to take drastic action and kidnap a group of male and female humans which they bring back to their homeworld. They would need to breed them just like they done with the Xenomorph race. An alien race that seems to have strangley disappeared...