Ferdinand IV
He was born before 15 April 1262 in Seville, the son of Alfonso X, King of Castile and León and Queen Violant of Aragon. In 1296, during the minority of his nephew Ferdinand IV of Castile, John was declared King of León, Galicia and Seville, although in 1300 he reconciled with Ferdinand IV and entered his service. In 1312, after the death of Ferdinand IV, he was appointed guardian of his son Alfonso XI, whom he served alongside Queen María de Molina and Infante Peter of Castile, Lord of Cameros.