|“Firstbourne is the mother of all dragons. Said to be the most powerful in the realm. No one's ever seen it entirely, but it is said to possess every Element of her beloved spawn.”|
|— Jet Jack to Rocky Dangerbuff|
The Firstbourne is the first dragon in existence and the legendary "Mother of All Dragons." She inhabits the Realm of Oni and Dragons and lives in the her nest most of the time. Ages ago, the First Spinjitzu Master befriended the Firstbourne, and with her help he forged the Dragon Armor. The Firstbourne protected her Dragons over the years, primarily from Iron Baron and his barbaric Hunters.
After many of her dragons were captured, the Firstbourne raided Dead's End and freed her captive offspring, before returning to her nest. Later, Iron Baron forced Wu to lead him to Firstbourne's nest, believing he could claim the Dragon Armor and control her with it. After claiming the armor, Baron learns this was a ruse, and the Firstbourne encases him in molten rock. After Wu dons the Dragon Armor, he and the Ninja fly the Firstbourne and her Dragons back to Ninjago, where they stage a final battle against Lord Garmadon and his forces. Following the battle, the Firstbourne returns to her home realm.
At some point, the First Spinjitzu Master befriended her, then, together they made the Dragon Armor. Afterwards they sought to stop the war in the Realm of Oni and Dragons. The Spinjitzu Master then realized the war could not be stopped, and left the realm. The Firstbourne remained in the realm and protected the Spinjitzu Master's Dragon Armor, always having faith that he would one day return for it.
Much later, Iron Baron attempted to hunt for her, but she took his leg and arm as a result. However, Heavy Metal was able to take the Dragonbone Blade from her. Since then, Baron has nursed a vendetta against the Firstbourne and leads his Hunters in searching for it to get revenge.
During the Ninjas' captivity, Jay remembers what Wu told him the first time he met him and decide to make a mech that looks like a Dragon, which the Hunters will believe is the Firstbourne to help out. Over the next few days, Cole and Wu build the Dragon with parts smuggled out by hiding them in Dragon dung and get them before disposing of it.
Later that night, Wu flew the Dragon mech before a shot from Iron Baron knocks the tail off and the real Firstbourne appeared to rescue her children. The Ninja initially confused her for their mech until they realize the truth and were shocked to see it up close.
As she was firing among the camp, Wu and the Ninja provide a distraction for Kai to free the Dragons before they get out themselves. Iron Baron yelled that the dragon was punishing them for hunting its offspring. The freed Dragons then flew to their mother and were able to escape the Hunters.
Iron Baron forced Wu to lead him to Firstbourne's Nest, where the sacred Dragon Armor is guarded. Eventually, the arrive in the nest and locate the armor. Iron Baron rushes to procure it, and does so just as the Firstbourne awakens and rises up before him. Baron hastily throws on the armor and commands the Firstbourne to kill Wu. However, Wu discloses that he lied about the armor having control over the Firstbourne, and revealed that she instead sensed the good in his father's heart, which allowed him to tame her.
Upon sensing the evil in Iron Baron, who rips the armor off, the Firstbourne unleashes a stream of molten rock and encases him in it. Firstbourne notices Wu and senses the good in his heart as it did with his father. Wu soon puts on the armor and allies with the Firstbourne and her family of dragons. He flies the Firstbourne out of the nest and reunites with the Ninja and Dragon Hunters. After the Ninja board dragons of their own, they fly off to return to Ninjago.
The Ninja fly back into Ninjago through a rift in the sky, with Wu leading apon the Firstbourne. They went down to where Lloyd, Nya and Dareth where fighting the Sons of Garmadon and sent the bikers fleeing away. After the team evacuated the people in the surrounding areas, Wu and Lloyd flew the Firstbourne up to Borg Tower, where they confronted Lord Garmadon. The three began fighting, with the Firstbourne eventually intervening and unleashing a stream of molten rock. Garmadon was incapacitated, but broke free and unleashed a burst of destructive energy. Wu was sent flying towards the streets far below, and was saved by the Firstbourne.
As Lloyd continued fighting his father, Wu flew the Firstbourne over to the Colossus, and helped the Ninja and their dragons to defeat it. After the successful battle to overthrow Garmadon and his forces, Wu said his "goodbyes" to the Firstbourne, as she would soon return to the First Realm.
- In the Hunted trailer, when she's using an elemental power, she can glow to the color of the element (When she used Fire she was glowing into a red-orange color, but when she used Ice she was glowing into a white-light blue color).
- She possess every Elemental Power (or Elemental Eseence Power) except Darkness and Destruction and guards the golden Dragon Armor, which the First Spinjitzu Master once wore.
- She bonded with the First Spinjitzu Master and together with her Fire and his Metal, they created the Dragon Armor, and sought to unite the two races and the realm along with them to end their war. They soared through the skies only with the respect they had for one another. After the two sides refused to end the war, the First Spinjitzu Master left the Realm of Oni and Dragons and went on to create Ninjago, leaving the Firstbourne behind to guard the Dragon Armor.