Perhaps we are putting the broo before the goat, so to speak. If there is a default morphology for a broo, what says it must be goat-like? If goats are plentiful in a region and are easy rape-prey for broos then a goat-like archetype might be established for that region. The goat-form results from the preponderance of reproductive outcomes with goats but is not a predetermined archetype. If however wild pigs dominate the region might we not expect to see a local archetype of horned-pig-form broo? Thus in the Prax might we expect to see lots of antelope-form and sable-form broo and fewer goat-form broo, except around the upper Zola Fel where goat, sheep and zebras might be more common. Of course laminated on top of this is the mutability caused by chaos, so distortions of archetypes should be common place one would think. Is there really a goat-form ur-morphology which tends toward goat-kin? The horns seem to be the only universal phenotype.
What are the limits to broo reproductive capacity? Can broo mate with anything capable of receiving the parasitic larvae? Could broo mate successfully with reptiles, large insects, dinosaurs, morokanth, fish, birds, mythical beasts, demons or plants? Is their ability to successfully implant larvae limited to mammals and proto-mammals? The possibilities from broo reproduction seem manifold and this may be their inherent strength. Perhaps we walk past broo trees and bushes and never know it!
Finally, how do broo larvae come about? Do all broo of all sexes reproduce their own larvae by asexual parthenogenesis and then implant them on their own? If so, why are there two sexes of broo? Or are the broo sexual creatures who mate within their own 'species', and then the females transfer the developing larvae to the males after fertilization and a short period of gestation, like many types of Earth's sea-horses do; these to be implanted in rape-prey victims later on by mobile and marauding males? This might give the female broo a more important role in broo reproduction than has previously been suspected and thus explains the need for females in the species.
Cheers.
Evilroddy.