The first Prometheus was an enigmatic film that didn't offer a lot in the way of answers. However, that will apparently change for the sequels, as they will fully explain where the aliens came from.
In a recent interview with IGN, director Ridley Scott implied that the upcoming Prometheus movies will delve into who created the Xenomorphs.
“Prometheus 2 will start getting shot in February and I’ve already begun now so I know what the script is," Scott said. "Then there will be another one after that and then maybe we’ll back into Alien 1, as to why? Who would make such a dreadful thing?”
The first Prometheus already appeared to explain that the Xenomorphs were created by the Engineers, and the last scene of the film is even a Xenomorph coming to life by bursting out of an Engineer's body. However, it sounds like either that isn't totally correct, or Scott means that the sequels will explore the specific Engineers who created the aliens in the first place.
Either way, Scott's quote also clarifies that Prometheus will likely become a trilogy, with the third one leading into the events of the original Alien.
Prometheus 2, which is actually now titled Alien: Paradise Lost, will shoot this February and will be released sometime in 2017. The script for the movie is currently being revised, reports Variety.