- —Alfin's intro quote, Trails of Cold Steel III
Alfin Reise Arnor is the crown princess of the Erebonian royal family, and Olivert Reise Arnor's younger half-sister in the The Legend of Heroes: Trails of Cold Steel trilogy. She attends the Saint Astraia Girls' School located in the capital city with her best friend, Elise Schwarzer.
She has long, wavy blonde hair and an angelic disposition. She is very popular amongst the people of Erebonia, and considered to be one of its "national treasures", the other being Cedric.
Alfin is a kindhearted noblewoman who is courteous toward others. She has a mischievous side, however, especially toward her close friend Elise. Nevertheless, she is supportive of Elise and the Courageous’ resistance, and similarly aids her kind, timid twin brother, Cedric. She recognises that her friend Elise has a crush on her adoptive brother Rean and often tries to push them towards each other, though Rean is oblivious.
Princess Alfin is a cheerful teenaged girl who loves teasing her best friend Elise Schwarzer especially to Elise's foster brother Rean Schwarzer. She enjoys reading boys' love stories, just as Dorothee does.
During the Erebonian Civil War Alfin and Elise are taken to Ymir Village by Toval and reunited with Rean in the process. However, she and Elise were later captured by the mysterious Black Rabbit, Altina Orion, and Vita Clotilde.
When Rean was captured and sent into Noble Faction's Flagship Pantagruel, Princess Alfin gave him advice that helped him learn to control his Ogre Form, allowing them to escape the clutches of the top warriors of the faction. She was later brought back to the Courageous as her personal ship and reunited with her half brother Prince Olivert.
Princess Alfin became the voice of the Class VII and Thor's student as the Third Faction in the Civil War where they were assigned to counter the Noble Faction in the Eastern Erebonia. On the other hand, Prince Olivert and Viscount Victor S. Arseid will help the Imperial Army in the West who are suffering great loss from the mighty army of Noble Faction Generals Aurelia and Wallace.
After the Civil War, she advances to the high-school division like Elise. However due to the dramatic changes after the war, she becomes deeply anxious about her twin brother's well-being and the explicit toleration from her older bother and the Vander Family.
- The name, Alfin, can mean "King" in Eastern languages.
- Alfin's bonding trophy in the SC2 is "National Treasure" if players chose her as Rean's Lover.