According to Chrétien de Troyes, the Fisher King’s father, also a king, was brother to Percivale’s mother and to her other brother the hermit. (In this version, it all seems to be pretty much a family affair.) In addition, the Fisher King’s kingly father is the person served from the Grail, which is processionally borne to him in the little room where he has lived for twelve years at the time of his nephew’s first visit.
The only food served him is Mass wafers, apparently one per meal. This is all he lives upon. The diet was far from unknown among saints beloved in the Middle Ages.