Perceval's earliest surviving full story is Chrétien de Troyes's unfinished Perceval, or the Story of the Grail, written in the late twelfth century. The hero grows up in isolation because his mother has lost her husband and older sons to the violence of knighthood. She keeps her youngest child in the forest, where he knows hunting and rough country life but almost nothing about courts, religion or chivalry. When mounted knights appear among the trees, their armour and weapons astonish him. Learning that they serve King Arthur, he decides immediately that he will ride to court and become a knight.

His arrival at Arthur's court is comic and dangerous. Perceval lacks the manners expected of a noble household and understands almost none of the customs around him. A Red Knight has insulted the king and taken a golden cup. Perceval rides after him and kills him with a hunting spear, then takes the dead knight's armour because he does not yet know the formal rules of combat. The episode gives him the outward appearance of a knight before he possesses the judgement of one.

That judgement begins to develop under Gornemant, an experienced knight who receives the young wanderer and teaches him how to use weapons, behave at court and restrain his impulsive speech. Gornemant's advice is sensible in ordinary society: do not ask endless foolish questions. Perceval then reaches the besieged castle of Blanchefleur, a young noblewoman whose people are suffering under attack. He fights for her, defeats her enemies and discovers a form of love and responsibility beyond simple adventure.

The lesson against questioning becomes disastrous at the Fisher King's castle. Perceval meets a wounded fisherman who invites him to a great hall. During the feast a strange procession passes before him. A youth carries a lance whose point drips blood. Attendants carry lights. A maiden bears the object Chrétien calls a graal, a richly made serving vessel whose later history will transform it into the Holy Grail. Perceval wonders what the objects mean and whom the Grail serves, but he remains silent because he fears appearing rude.

By morning the castle is empty. Perceval later learns that the question he failed to ask would have changed everything. A grieving maiden condemns his silence, and later a hermit teaches him to recognise the spiritual cost of his earlier ignorance. Chrétien died before completing the romance, leaving Perceval's final return unresolved. Later continuations send him back to the castle, let him ask the necessary question and, in some versions, make him the successor or healer of the Grail king.

The Welsh Peredur son of Efrawg tells a related but distinct story. Peredur is likewise raised away from warriors, reaches Arthur's court and encounters a mysterious procession, but the objects include a bleeding spear and a severed head on a platter rather than the developed Christian Grail of later French romance. He also meets the Nine Witches and pursues vengeance connected with the severed head. The similarities are strong enough that the two traditions belong to the same wider family, but Peredur should not simply be treated as another spelling of every French Perceval episode.

Wolfram von Eschenbach transforms the hero into Parzival, expands his family and gives the Grail realm the name Munsalvaesche. His wounded Grail king is Anfortas, and Parzival's eventual compassionate question heals him. The Vulgate Cycle later changes the hierarchy of the Grail quest by introducing Galahad, the supremely pure knight who achieves the highest vision. Perceval remains one of the central Grail companions beside Galahad and Bors, but he is no longer the single chosen hero.

Thomas Malory keeps the knight as Percivale in Le Morte Darthur, drawing heavily on the prose Grail tradition. Richard Wagner's nineteenth-century Parsifal returns to the motif of the innocent fool whose compassion brings healing. Across these versions, Perceval's defining quality is not perfect purity from the beginning. It is growth. He enters the story unable to understand the people and symbols around him, fails at the moment of greatest opportunity, and becomes important because he learns that courage without compassion and attention is incomplete.