Nabatea

They are dragons similar to manaketes, though the term "dragon" is almost never used for them in the story itself; instead terms such as "Children of the Goddess," "Creature," and "Divine Beast" are used in different contexts. They possess both a humanoid form and a large, monstrous form created using energy generated by their Crest Stone (the magical stone that serves as the heart of a Nabatean). The monstrous forms vary greatly among individuals, but all are at least partially reptilian.

Another feature of their bodies (both the humanoid and monstrous form) is that they do not naturally decay after death, enabling objects built from their corpses to persist indefinitely. Such items will also continue to move/pulsate as if alive, so long as the Crest Stone is still implanted in them. It is possible for a Nabatean to lose the ability to transform into their monstrous form, and for those that maintain the ability there can be restrictions/dangers in overusing it.

All known Nabateans possess green hair, green eyes and pointed ears in their humanoid forms; as well as green blood in their monstrous forms. This blood is a major aspect of the story and setting, as transfusing the blood into a human will grant the human a number of powerful boons, namely the power of that Nabatean's Crest (a special power in their blood distinct from their Crest Stone) and a lifespan that spans centuries with little or no visible aging beyond the point when the transfusion occurred. The descendants of someone with a Crest may also inherit the Crest, however, they will not have the increased lifespan, and will age normally.

In ancient times, the progenitor god arrived in Fódlan from an unknown location far away, often theorized by humans to be from the Blue Sea Star. She took on a humanoid form and used her blood to create her children, the Nabatean people. For a while, the Nabateans were able to coexist with the native humans of Fódlan, scattered across Fodlan and acting as rulers while sharing knowledge and skills to help them build a prosperous civilization: Agartha.

Eventually, the Agarthans turned away from the progenitor god's teaching, warring among themselves and advancing their technology ever further, to the point that they began to consider themselves to be gods as well. They even challenged the progenitor god directly. The ensuing war devastated the continent, forcing the progenitor god to spend an immense amount of time (implied to be at least a thousand years) and to expend most of her energy to heal it and then retire to her Holy Tomb at Zanado in the Oghma Mountains to slumber. The Agarthans who escaped the wrath of the progenitor god retreated underground and began plotting their long revenge, becoming Those Who Slither in the Dark.

Later, Those Who Slither in the Dark manipulated a bandit named Nemesis, who sought to liberate Fódlan from invaders, into breaching the Holy Tomb and killing the progenitor god in order to forge weapons such as the Sword of the Creator and create the Crest of Flames from her body. Nemesis went on to slaughter the Nabateans at Zanado, bestowing Crests upon his strongest warriors, the Ten Elites, as well as weapons crafted from the bodies of the slaughtered Nabateans; together they defeated the invaders and Nemesis became a king. Only Seiros (the lone survivor at Zanado) and four other Nabateans (who were living elsewhere at the time), including Cichol and his daughter Cethleann, are known to have survived the extermination of their people. Enraged and grief stricken by the loss of her mother and people, Seiros gathered the surviving Nabateans and persuaded Wilhelm Paul Hresvelg to ally with her in opposition to Nemesis, giving him her own blood and the Crest of Seiros. Wilhelm founded the Adrestian Empire with Seiros' assistance, ushering in the War of Heroes. After nearly a century of fighting, Seiros slew Nemesis in Imperial Year 91 at the Tailtean Plains. Following the war, Seiros used the Church of Seiros to rewrite history and hide the origins of crests, Heroes Relics, Nemesis, and the Ten Elites, eventually taking on the name "Rhea".