Eir

Eir is a character that appears in Fire Emblem Heroes Book III. She is a princess of Hel.

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When the seal keeping Hel's forces out of Zenith weakens, Hel unleashes her army and orders Eir to join the forces of Askr. Eir confronts the Order of Heroes and is defeated. She asks to join them, but being the princess of the enemy, suspicion is immediately cast on her. Instead, the Order holds her prisoner, however she asks the Summoner to let her fight with herself willing allowing them to kill her should they suspect her betrayal at its first instance.