Lancelot

Lancelot is not old. He has no Welsh ancestry and no place in the chronicles; Chrétien appears to have invented him around 1177, at a patron's direction, and within fifty years he is the centre of the entire French tradition.

What Chrétien invented was a mechanism. In The Knight of the Cart Lancelot must ride in a cart used for condemned criminals in order to follow the abducted queen, and to do so is permanent disgrace. He hesitates for two steps. That hesitation is the only thing the poem holds against him: Reason, which dares thus speak to him, reaches only his lips, but not his heart; but love is enclosed within his heart. Love overrules reason, and the result is the best knight in the world.

The Vulgate then drew the conclusion Chrétien had avoided. If the Grail requires purity, the man made supreme by adulterous love is structurally disqualified from the highest thing there is. So Lancelot rides the quest and fails it — and the failure is the most affecting sequence in the cycle, because he is not a hypocrite. He tries. He confesses. He is told plainly that he will go no further, and he accepts it, and his son achieves what he cannot.

Malory keeps all of this and adds the ending. Lancelot rescues the queen from the fire and kills Gareth and Gaheris doing it, unarmed men he loved, without seeing who they were — and that single accident, not the adultery, is what makes the war unstoppable, because Gawain will not forgive it. He gives the queen back, is exiled, is besieged, is called home too late, finds Arthur dead and Guinevere in a nunnery, becomes a priest, and starves himself to death.

Malory's final judgement is put in Ector's mouth over the body: the courteoust knight that ever bare shield, the truest friend, the kindest man that ever struck with sword. He does not mention the queen.