Four types of fools are important in fantasy.
2. The usage associated with the Perceval motif: a naive innocent fails to ask the questions which would resolve a situation – in Perceval's instance the wounds of the Fisher King – and who subsequently Learns Better and redeems himself and the Land. By extension, fools in this category may fail to answer Riddles, or may ask or answer questions in a wrong spirit or context.
3. The figure whose preparedness to diverge from the Quest to assist (e.g.) wounded animals is often seen by the rest as a fool; Androcles is an Underlier. This is a frequent Christian-Fantasy motif in which worldly folly becomes seen as heavenly wisdom.
4. The fool of the Tarot pack. [RK]