FireHunter, we were talking about Inferno Alien's concept, which is, in essence, identical to your own. I am not trying to criticize anyone's character, but fire breathing and being immune to fire
is an extreme concept. To prove my point, I have read over your xenomorph's profile and have provided the information which makes such a concept as extreme as it is.
-This is for constructive purposes
only. I am not trying to offend anyone, nor am I trying to create any sort of trouble.-
The first thing I would like to tackle is that predaliens are not immune to fire. They are just like any other xenomorph.
Xenomorph DNA would not be acquired and assimilated by biting or consuming an embryo. Rather, anyone who bit a facehugger's implantation tube would instead recieve a very nasty burn from the facehugger's acidic blood and would digest the xenomorph embryo/fetus, breaking down its genetic code and makeup for raw nutrients. No DNA would be merged with the a consumer, it would essentially be the same as eating a hamburger.
Additionally, even after being exposed to xenomorph DNA, a creature would not suddenly gain the ability to spit venom after being wounded by a poisonous organism. To spit venom, a creature needs a special pair of glands to produce, store, and release said toxin. Even then, a wound to the leg would never bestow any organism with the ability to transfer venom because it must be synthesized by the organism-- a process which could never be acquired through being injected with poison. Rather, a poisonous wound to the leg would most likely ail, hinder, or kill the individual, and nothing more.
To acquire the capability to spit venom, a xenomorph would have to have been spawned from something already in possession of that ability. Even then, there is a chance that it would not recieve that trait.
Finally, being shot in the mouth with a flare would never grant a creature the ability to breathe fire. A flare is an inorganic object, which produces an intense amount of heat and light. Neither heat nor light can be assimiliated by an organism, xenomorph or not, and any individual shot with one there would experience an extremely nasty burn and probably be unable to taste anything for around a month. Even still, being capable of producing fire would, once again, require a set of glands to produce reactive chemicals which, when combined, would combust and produce heat energy. Being shot in the mouth by a flare does not produce either the glands nor the chemical synthesis to create these components. It would also never create an immunity to fire.
To put it simply, there is no real way for any character to gain the ability to breathe fire. Xenomorphs (Predaliens included) do not breathe to begin with, and there is no organism on this planet that can produce fire on its own. The closest thing to that would be the Bombardier Beetle.
I do not mean to insult or offend anyone, but the things which compose a fire-breathing creature are nearly impossible and highly confusing...it's a good example of an extreme concept. Once again, I am
not trying to upset anyone, I am merely backing up my statement that being able to breathe fire or being immune to fire are both very extreme adaptations.
However, I would be more than happy to help you and any other individuals that want heat-related xenomorphs / predaliens make more probable and practical characters...I still have a few tricks up my proverbial sleeves.
*sigh* Okay. Zoology. Right. Dragons would most likely either fit into a new genus of their own or be classified as reptiles. Insects are classified by their number of legs, the possession of an exoskeleton, and their overall biological structuring, such as their circulatory and respiratory systems. Furthermore, if we are counting wings, a typical insect possesses 8 appendages, not six.
A dragon, as far-off as it can be, is more reptillian than insectile. Given, it would not be cold-blooded, but a "common" dragon possesses scales, a tail, is quadrupedal, and produces eggs, not live offspring. It is much more similiar to a reptile than an insect. However, as I have said, it would not fit into the category comfortably, and would most likely create its own niche.
As for the frog-spawned xenomorph, I could certainly see how it would take longer for a chestburster to develop within such a creature, especially due to the fact that amphibians are cold-blooded and possess a slowly-moving circulatory system and a rather slow metabolism, which in turn means that it would take much longer for the chestburster to gain the necessary nutrients to grow.
And thus I clothe my naked villainy
With old odd ends stolen forth from holy writ
And seem a saint when most I play the devil.