-Bloo-,
Yautja,
11 years ago
It hasn't exactly been shown in the films (the closest example being the Newborn-Queen exchange and the infamous "Escape" plan, both instances from Resurrection), but every other media type has shown full scale hive wars, the most notable titles being Female War (I think) and Extinction. Just keep in mind that these aren't considered canon (though if you're like me and you like the idea of Praetorians and all that other bullshit, it's almost certainly plausible).
The reasons for Xenomorphs fighting their own kind would be purely for territorial issues between rival hives, meaning Xenomorphs from the same hive wouldn't normally fight each other. There are concrete examples (which are, again, not a part of film continuity):
- Hive A's population has reached its 'limit.' One or more Xenomorphs branch off from Hive A to either a)capture a host to turn it into an egg that houses a Superfacehugger, which has the ability to carry a Queen Embryo, or b) hide away somewhere to morph into a Queen itself. After establishing a hive of its own, Queen B is in a power dispute with Queen A. Queen B was technically a part of Queen A's hive, which means Xenomorphs from the same hive are now fighting each other. (Usually, the Queen that comes out on top becomes an Empress. Many people argue over what exactly an Empress is, whether it be just an old Queen that's grown to a large size, a completely different strain of Queen that's also larger than a normal one, or just a title for the Alpha Queen of a planet/area).
- It's known that, if a group of Xenomorphs are being held in a cage, they might exploit the fact that they have acidic blood to escape. In Resurrection, the weakest Xenomorph of a bunch was mauled by the others in order for the blood to eat away at the cage walls, ensuring escape. The weak Xenomorph didn't die willingly, and if I remember right, they were arguing over which one would die - essentially, Xenomorphs from the same hive were fighting. (A thing to also keep in mind, however, is that these Xenomorphs were different from your normal ones in that they had human DNA in them, which made them, among other things, possibly more intelligent.)
- In order for lesser Xenomorph strains to become Praetorians, they must emit certain pheromones from their bodies that makes the entire hive hostile towards them. During this time period, if the pre-Praetorian were to stay in the hive, it would be attacked by every single one of its brothers. At this point, it can either run and return after fully morphing, or stay and defend itself. Again, Xenomorphs from the same hive attacking each other.
- If the Alpha Male's an asshole, this provokes the leader of the Praetorian guard to harass said Alpha until the Alpha is killed by a human soldier in a fight to the death. By this point, the Praetorian is so overwhelmed that it commits suicide by fighting Queen A. Also, the Praetorian was a bigger asshole.
That last one's really uncommon. Sometimes the Alpha has to kill an Elder Predator before fighting the human. Don't ask me, that's just the way it works.