Question: Why do the Predators care about the PredAlien so much? I know it wiped out a few of them and is a monstrosity of a hybrid. However, why did they have it locked up on the ship? There is no way it got to full size (taking a few months I assume) or crawled around as a baby without a single Predator noticing. It must have been locked up, but if it's so bad, why keep it alive?
Chosen answer: The predalien, like all other alien species, is a trophy. They were probably keeping it alive so they could hunt it later.
Answer: They were not keeping it alive. Once it birthed it went somewhere to hide until it grew to full size. Much like in every other Alien film, the predalien grows to full size remarkably fast. It usually takes less than a day in most situations. Once it grew to full size it began slaughtering the Predators and proved to be more than a match for the average Predator. They were most certainly not keeping the predalien alive purposefully, they had no idea it even existed until it began killing them.
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