Fiora

Fiora is the older sister of Farina and Florina and the commander of the 5th Wing of Ilia's Pegasus Knights. She has a solid relationship with Florina, helping her grow as a knight despite her mistakes. She often quarrels with Farina, which stems from an incident in the past. Farina once got into danger during a practice maneuver, forcing Fiora to abandon her mission to rescue her. This unfortunately caused her to gain a massive termination fee. Upset that Fiora gave up her honor for her sake and Farina told her that she should have left her to die. The two got into a bitter argument, leading to Farina leaving to become a mercenary.

(Source: Fire Emblem Wiki)