Reginn

Reginn is a playable character that appears in Book V of Fire Emblem Heroes. She is the younger sister of Fáfnir and Ótr.

Reginn does not remember much about her family aside from the fact that she was orphaned with her older brother Ótr after the old king of Niðavellir was killed and the kingdom descended into chaos. Amidst the chaos, the siblings found shelter in a village where they were later discovered by Fáfnir who took the siblings into his care. While supportive of her new stepbrother, his actions overtime became a concern for her, especially when he began invading realms. Despite this, she remained supportive of him, in hopes that he would return to the kind king he once was.

When Fáfnir sets his sights on the Kingdom of Askr, Reginn is sent to lead the invasion and capture the summoner under Ótr's orders, though the reason behind it is not disclosed to her. This order leads to an encounter with Alfonse and his forces who have just recently escaped from Dökkálfheimr. Despite a well fought battle, she is defeated and forced to retreat. She later reengages the Askran forces and Alfonse notices that she lacks conviction in her actions. After being defeated a second time, she cries for her failure. Alfonse and Sharena console her and seeing their kindness despite being enemies only moments ago, Reginn pleads to the Askr forces to help her stop her brother's madness.

On their way to see Eitri, a sage whom she believes can stop Fáfnir, Reginn and the Askran forces encounter Ótr who is stunned to see her cooperating with them. Reginn voices her intent to stop Fáfnir, leading to her brother disowning her for her betrayal of her kingdom.

Reginn is a kind-hearted, gentle princess who cares greatly for her two brothers. Fáfnir and Ótr's sudden change in personality, which she states are full of rage, is deeply concerning to her. Despite this, she faithfully obeyed their orders in the hopes that they may one day return to their former selves. She even cried when she felt that she had failed them after being defeated by the Askran army twice. However, her encounter with the Askran army proved to be a window for her to ask someone for help in the hopes of returning her two brothers to their original selves.

Considered as the tomboyish Niðavellir royal, she claims to be an excellent cook and is eager to show her cooking skills.

(Source: Fire Emblem Wiki)