Bodwyne, Boudin
The good Prince Boudwin, honorable and well beloved by all the people of Cornwall, was King Mark’s brother in Malory.
Once, when the Saracens landed in Cornwall shortly after the Sossoins had gone, Boudwin
raised the country privily and hastily,
put wildfire in three of his own ships, caused them to be driven among the ships of the Saracens, and so burned their entire navy. Then Boudwin and his men set on the Saracens and slew them all, to the number of forty thousands. Mark went wild with jealousy and murdered Boudwin, by stabbing him in the heart with a dagger.
Boudwin’s wife, Anglides, fled from Mark’s court with her young son, Alisander le Orphelin, to Magoun’s Castle. Alisander’s son, Bellangere (Bellengerus), later avenged his grandfather’s murder.
Boudwin’s Doublet and Shirt
Boudwin’s widow kept the bloody garments to give her son Alisander when he grew up and was of an age to think about avenging his father. This is similar to Sir La Cote Male Taile’s wearing the coat in which his father was murdered until he could avenge that deed.
The character seems to have been adopted from Pernehan, Mark’s doomed brother in the Prose Tristan.
Source
Le Morte Darthur | Sir Thomas Malory, 1469-1470