Lukas

A loyal member of the Deliverance, Lukas grew up on the borderlands of Zofia. His older paternal half-brother saw him as a rival, despite being younger, and forced Lukas to enlist in the Deliverance. He eventually becomes a Soldier whose considerable merits have caused him to rise quickly up the ranks. He came to Ram Village to recruit Mycen when Desaix took over Zofia castle. However, Mycen refused his request. Alm then decides to join in place of Mycen. For the majority of the game, he acts as an older brother figure and mentor to Alm.

(Source: Fire Emblem Wiki)