Before Alexei Dinoia's death, Yeager is sometimes seen arguing with Alexander von Cumore, as well as helping him to escape. After his and and his benefactor's death, Yeager's underlings explain to the group that he fought to protect them because Alexei discovered he was paying the debts of the orphanage where he adopted the girls. Yeager has an indirect connection with Raven, having been romantically involved with Casey, a now-deceased female knight, who had also been dear to Raven in the past. Yeager is in possession of Casey's prized weapon, a bow, until Gauche and Droite surrender the weapon to Raven in return for Casey's compact mirror. Yeager and Raven were also both subjects in Alexei's experiments with blastia, and like Raven, Yeager has a Hermes blastia keeping him alive.