Iron Dragonborn

The Empire prides itself on having an answer to every problem. When ships need boarding, they send in fast-moving frigates packed with bloodthirsty half-orc marines. When a castle needs undermining, they bring in a team of dwarven engineers. When a King needs to be put in his place, they send a Praefect. And when an enemy position needs to be hit hard and fast, they turn to the Iron Dragonborn.
Created and introduced to the world around the same time as the Iron Dragon, Iron Dragonborn were bred to serve as loyal, tireless and ferocious shock troops in the Emperor's armies, dropping from the sky on grey-membraned wings and landing right in the heart of battle clad in full plate armour, laying all about them with warhammers and greataxes. They have been a feature of the Imperial army since its very first conquest, and as a consequence, are viewed with fear by all those who have suffered at the hands of Midaevians. It is fortunate then, for both the people of the empire and its enemies, that the iron dragonborn, unlike the others of their kind, are permitted to live nowhere but the Blackthorn Mountains.
Physiology and Society
Physically speaking, iron dragonborn share many characteristics with their more common variants, apart from two critical differences; they are not able to emit a breath attack, but this is counterbalanced by their strong, powerful wings which allow them to dominate the skies alongside their uneasy neighbours, the iron dragons.
The societal differences between irons and other dragonborn, however, are vast. As a relatively young race, the irons do not appear to have reached a level of development comparable with the rest of Imperial civilisation. Their people cluster in tribal-like villages in imitation of stone age hunter-gatherer societies. Under ordinary circumstances, they would likely have seen their numbers drastically reduced due to infighting or poverty. However, the defining factor of iron dragonborn society has, and always will be, their relationship with the Empire. Since the dawn of their creation, iron dragonborn have pursued two constants; their belief in the Elder One, and service to the Emperor's bloodline. Thanks to the influence of the Church, they believe their species to have originated from that same blood-line, and view each iteration of the Emperor as a familial figure. As a side effect of this, iron dragonborn view themselves as "purer" than others of their kind. Other dragonborn are viewed as weak and lesser, and in the unusual event of a mixed-breed occurring, they will usually drive them out, if not just kill them outright.
As a consequence of this, all iron dragonborn are instilled with unwavering devotion to the rule of the Imperial Dynasty. Children are taught from an early age to be prepared to give their lives, if required, to "The Iron Master", and the Empire.
This has had the effect of leaving the irons in a state of perpetual barbarity, a condition that suits the Empire perfectly. By providing them with every possible amenity; generous supplies of food, healers from the Praepostors, iron-forged weapons and armour, and of course, regular sermons on the teachings of the Four Gates given by Church priests, they allow the irons to focus all their energy on martial pursuits. This way, should the need arise, they have an entire civilisation of zealous warriors ready to literally drop everything and march to war. And if the irons ever started harbouring thoughts of disobedience, unlikely as that might be, the Empire can easily starve them back into submission.