War of the Castilian Succession
Fadrique was very close to the Catholic Monarchs. His father had fought in the War of the Castilian Succession on the side of the future Queen Isabella I of Castille against her niece Juana la Beltraneja, and his mother was the younger half-sister of Juana Enríquez y Fernandez de Cordoba, making him the first cousin of Ferdinand II of Aragon.