Anyways, back on topic...
A long time ago, I remember watching a fan-made short film, all CGI and looked similar to that old Transformers show Beast Wars. The premise was an explanation to the conflict between the different creatures. In a nut shell, Predators were battling Engineers on a full-out war. The Engineers, in turn, created the Aliens (Xenos) as a means to defeat the Predators. As it turned out, according to one fan's perspective, the Engineers were all but wiped out (coinciding with Aliens: Earth War story arc) and the Xeno infestation became a wide-spread problem. The Predators respected the Alien species as a worthy prey, gathering specimens when able and using them for hunts (like the AvP movie/graphic novels).
This was well before the BSP's were a thing, as well as Prometheus. I still think it's a cool prospect.