Lohengrin

Lohengrin is a character in some German Arthurian literature. The son of Parzival (Percival), he is a knight of the Holy Grail sent in a boat pulled by swans to rescue a maiden who can never ask his identity. His story is a version of the Knight of the Swan legend.Lohengrin first appears as "Loherangrin," the son of Parzival and Condwiramurs in Wolfram von Eschenbach's Parzival. Loherangrin and his twin brother Kardeiz join their parents in Munsalväsche when Parzival becomes the Grail King; Kardeiz later inherits their father's secular lands, and Loherangrin remains in Munsalväsche as a Grail Knight. Members of this order are sent out in secret to provide lords to kingdoms that have lost their protectors and Loherangrin is eventually called to this duty in Brabant, where the duke has died without a male heir. His daughter Elsa fears the kingdom will be lost, but Loherangrin arrives in a boat pulled by a swan and offers to defend her, though he warns her she must never ask his name. He weds the duchess and serves Brabant for years, but one day Elsa asks the forbidden question. He explains his origin and steps back onto his swan boat, never to return. The Knight of the Swan story was previously only known from tales of Godfrey of Bouillon's ancestry and Wolfram's reasons for incorporating into Parzival are not obvious, though it is not the only altered version of a popular story he uses in his narrative (he makes Prester John the son of his character Feirefiz).
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[Arthurian] Parzival's son in Wolfram von Eschenbach's Parzival. He must keep his identity and history a secret. His wife, the Princess of Brabant, insists on questioning him and breaks the spell and Lohengrin is borne away by a great swan. Further treatment can be found in the 13th century German romance Lohengrin. In Richard Wagner's opera, it is explained that the Grail gives it's guardians magical powers that depend upon them maintaining their anonymity.