Rutger Claussell (ルトガー・クラウゼル), also known as the Jaeger King (猟兵王), was the leader of the jaeger corps Zephyr and foster father of Fie.
Rutger and his long-time rival Baldur Orlando of the jaeger corps Red Constellation fought each other until both lost their lives in S.1203. After his death, the members of Zephyr each went their own way and Sara Valestein, who witnessed the decisive battle, and took in Fie.
After Zephyr regiment commanders Xeno and Leonidas suggested they were trying to resurrect their leader at the end of the Erebonian Civil War in S.1204, Rutger appears to be alive again in S.1206.
↑This DOB assumes that his official age (50) includes the years he was dead.