János VI was the former King of Fenario in Brokedown Palace. At some point, part of the palace collapsed, severely injuring him. He resigned as ruler, handed the crown to his eldest son László, and retired, with his wife Teréz, to remain permanently in bed in the top of a tower.
Their sons did visit with them occasionally.
One of the folktale interludes in Brokedown Palace describes how a young János got his wife, who had been stolen by the elfs. We have no idea how much truth there is in this tale, if any.
János was killed, along with his wife, during the destruction of the Old Palace of Fenario.