"The Queste is part of the compilation called the Prose Lancelot (1215-1230), which deals with the adventures of Lancelot and his love affair with Guinevere. There are warnings in the Lancelot that his adultery with Guinevere will debar him from achieving the Grail, and the author of the Queste invented a new character as the Grail-winner, Galahad, who was 'so grounded in the love of Christ that no adventure could tempt him into sin." - Richard Cavendish, "Grail", Man, Myth & Magic, An Illustrated Encyclopedia of the Supernatural, Vol. 9

According to the noted authority  Prof. R.S.Loomis Lancelot's family tree starts with a heathen king Evalach and his brother in law Seraphe. On their conversion to Christianity they take the names of Mordrain and Nasciens. from Nasciens- Celidoine, Marpus, Nasciens II, Alain le Gros, Ysaies or Helyas, Jonas, Lancelot I, Ban, Lancelot II (Arthur's) and Galahad. 

"Three Knights of Battle were in the court of Arthur: Cadwr the Earl of Cornwall, Launcelot du Lac, and Owain the son of Urien. And this was their characteristic,- that they would not retreat from battle, neither for spear, nor for arrow, nor for sword. And Arthur never had shame in battle the day he saw their faces there. And they were called the Knights of Battle."

related pages

 Alfred, Lord Tennyson - 'The Lady of Shalott'

Alfred, Lord Tennyson -  'Lancelot and Elaine'.

Sir Thomas Malory, Le Morte d'Arthur - Book 6