First Dragons

The First Dragons (神祖竜 Shinsoryū, lit. Divine Ancestral Dragons in the Japanese version) are ancient dragons from long ago in Fire Emblem Fates.

Overview
Long ago, twelve powerful dragons waged war on each other to determine who would control the world. One of the Dragons, the Rainbow Sage, forged the legendary weapons Yato, Fujin Yumi, Raijinto, Brynhildr, and Siegfried as a means to fight them. However, humanity was selected to wield them, plunging them into the Dragons' war.

It is said that the current nobility of Hoshido and Nohr all acquired their Dragon Vein ability thanks to their ancient lineage to the Dawn and Dusk Dragons respectively. Similarly to the Manaketes, the surviving First Dragons can suffer from degeneration if their primal instincts are left unchecked.

Before Fates
Some of the history of the First Dragons is recited in the Ancient Texts in the Record's Hall. These texts mention a war between fellow dragons, with some of these dragons using humans as pawns for furthering their goals. The dragon's blood bonded with their chosen humans and granted them incredible power. The motives behind this war are unknown, and eventually the First Dragons themselves fell to death or madness while their blood bonded descendants persevered. After the disappearance of the majority of the First Dragons. Anankos himself remained in Valla for a time as a benevolent figure to its people. However, from time to time, Anankos would begin to degenerate and thus, the King of Valla would have to sing the song Lost in Thoughts All Alone in order to suppress his descent. However, as Anankos had feared, one day his degeneration became so strong that he lost control of his emotions and accidentally killed the King of Valla. With no person capable of quelling his instincts, Anankos rapidly degenerated, plunging Valla into chaos and destruction.

Shortly before the events of Fates a "fragment" of Anankos sought help from a country in another world. Arriving in Ylisse, he calls out to three warriors who helped to quell a Fell Dragon. Thinking that they could provide the key to help his child one day take down his dragon form, he enlists their aid to stop his madness.

During Fates
There are two known full blooded First Dragons that exist during the events of Fates, as mentioned above, the two are Anankos and the Rainbow Sage. Anankos takes the role as the primary antagonist due to his degeneration, while the Rainbow Sage takes a passive role in giving the Avatar some advice and power for their Yato in all three routes. However in Conquest and Revelation the Rainbow Sage dies shortly after upgrading the Yato. He survives in Birthright, but he suspects he will be long dead before he can see the Avatar's accomplishments for himself.

During the events of the Birthright and Conquest campaigns, the existence and identity of Anankos is unknown due to the curse he placed on Valla at an unknown time in the past. In the Revelation campaign Azura is able to explain who the true enemy is to the Avatar when they first travel to Valla shortly after Chapter 6.The Avatar gathers the combined strength of Hoshido and Nohr and kill Anankos.

Known First Dragons

 * Moro - An Astral Dragon.
 * God of the Flame - Ancient Dragon worshipped by the Flame Tribe.
 * Rainbow Sage
 * Dusk Dragon - Ancestor to the Nohr royal family.
 * Dawn Dragon - Ancestor to the Hoshido royal family.
 * Anankos - The Silent Dragon of Valla once known as the Dragon of Wisdom.

Trivia

 * The fact that there were twelve dragons who bestowed their power and weapons to their human champions could possibly be reference to Genealogy of the Holy War, as there had been twelve dragons who had formed blood pacts with the Divine Crusaders at the Miracle of Darna.
 * Much like the dragons of Fates who remain largely a mystery, only a few dragons whose identities had been confirmed by name; Naga, Forsetti, Salamand and Loptyr.