Virion

Virion is the former duke of Rosanne, a fallen country in Valm. In his support with Panne, it is revealed that he fled Rosanne because he believed otherwise the people would've died for him defending against Walhart.

Virion is introduced and recruited in Chapter 1. When Sully enters the field, Virion appears and immediately tries to court her with little success. He joins the army and also explains to Robin how to use bow-using units properly. Two years after defeating Gangrel, Walhart, Conqueror of Valm, begins an invasion of the Continent Ylisse. Virion and one of his retainers, Cherche, leave Valm and heads east to Ylisse to seek aid from Chrom and Ferox after revealing his true identity.

(Source: Fire Emblem Wiki)