Pionel, Pyonel
In Malory, Sir Pinel was a cousin to Sir Lamorak and a Knight of the Round Table.
For “pure envy and hate”, Pinel tried to poison Gawaine and avenge the death of Lamorak. The poison accidentally killed Sir Patrise of Ireland instead. After lying low while his cousin, Mador de la Porte impeached Queen Guenevere for Patrise’s death and Lancelot fought to save her life, Pinel “fled into his country” when Nimue uncovered the truth.
This may be the same Sir Pinel mentioned as “a good man of arms” who fought on Arthur’s side in the battle of Bedegraine.
In Vulgate Mort Artu, the name of this mortal enemy of Gawaine’s is Sir Avarlon (Avarlan). As Pinel in Malory, so Avarlon in the Vulgate tries to poison Gawaine with apples at a small dinner party given by the Queen. Here, Sir Gaheris de Kareheu falls accidental victim (do not confuse this Gaheris with Gawaine’s brother).
Source
Le Morte Darthur | Sir Thomas Malory, 1469-1470