Idunn

Idunn is the final boss of Fire Emblem: The Binding Blade. She is the Demon Dragon who is also known as the Dark Priestess.

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Several centuries ago, Idunn's tribe, the Divine Dragons had remained neutral in the Scouring, a deadly war in which humans and the Dragon brethren both shared the goal of total extermination of the other side. However when the Dragons started to lose due to their inability to keep up with the numerous and fast breeding humans, the dragons appealed to the Divine Dragons for volunteers to turn into a Demon Dragon and increase their forces with artificially spawned "War Dragons."

When the Divine Dragons refused to do so and disappeared, Idunn stayed behind because she feared the Divine Dragons would go into conflict with the others and was captured. Idunn was made into the Demon Dragon, but when she would not follow the commands given to her, the dragons removed her soul in order to gain control over her. Now an empty shell sworn to obey the leader of the dragons, Idunn started creating war dragons at an incredible rate.

With the endless number of War Dragons, the Dragons now had the advantage over humanity, however when all hope seemed lost for the humans, the Legendary Heroes of humanity rose to prominence, each wielding a legendary weapon created by combining the best technology and magic.

With this new advantage, humanity began to lead the final push against dragons. This culminated in a final battle in the Dragon Temple, where Idunn resided. In the massive battle, the sheer power of the legendary weapons led to the Ending Winter forcing Dragons to become Manaketes.

As human stormed the temple, they killed the Dragon's leader and wiped out virtually all dragons within the temple. However when the heroes reached Idunn, they saw only a sad shell of a little girl, staring into space with no orders to obey. The leader of the heroes, Hartmut felt pity for Idunn, having heard of rumors of her tragic plight, but unwilling to let her potentially endanger humanity, chose to seal her away with the Binding Blade.

About a millennium after her defeat, she is unsealed by Zephiel, Hartmut's descendant and current King of Bern, and serves him as a vital part in his scheme to bring new order to the world by replacing humanity with the emotionless war dragons.

Before his death, Zephiel ensures Idunn will continue to follow his commands in case of his death and entrusts her protection to Jahn, the last Fire Dragon left on Elibe and the only survivor of the battle at the Dragon's temple.

If the player collects all the Legendary Weapons, Roy will go out to find Idunn after defeating Zephiel. Despite Roy's pleas and insistence that she should not follow the now deceased Zephiel's commands, she refuses to submit and transforms into her dragon form to attack his army.

If Roy deals the final blow with the Binding Blade, Idunn once again survives her battle and is taken to Arcadia; she is seen laughing and playing with Fae, finally showing signs of recovering her soul. If the player fails to get all the Legendary Weapons, the game ends after defeating Zephiel, and Idunn will disappear.