Perceval is the "Fool" in De Troyes because of his naÏveté. Having grown up sheltered from the influences of the world by his mother, Perceval does not understand the ways of the world. For instance, when he first sees Arthur's knights, he thinks that they are Angels because of their bright armor. Another moment when Perceval's simple-mindedness is demonstrated is when Kay scorns him by suggesting that he fight the Red Knight in order to take his armor. Perceval takes this suggestion literally. Despite this, Arthur manages to recognize that Perceval is of noble blood;

"Kay", said the king, "for the love of God. you are too eager to speak ill, and it doesn't matter to whom! This is a wicked vice in a gentleman. Though the boy is naive, still he may be of very noble line; and if his folly has come from poor teaching, because he had a low-bred master, he can still prove brave and wise." (393)
Selections from Chrétien De Troyes' Arthurian Romances. Translated by Carleton W. Carroll