Physical DescriptionPryderi was as tall as Gwydion, with long golden hair that framed his brow and looked like a helmet from a distance. He wore rich raiment of crimson, black and gold, that glittered under torchlight.
Pryderi's armies were expected to make up the bulk of Caer Dathyl's defenses. Yet Pryderi had grown scornful of the petty bickering between the cantrev lords under High King Math's rule, and secretly made an alliance with the Death-Lord, believing that his rule offered the only prospect of peace and unity. Pryderi's arrival at Caer Dathyl proved disastrous for the Sons of Don, for though Math's forces under Gwydion had gained advantage and begun to push Pryderi's forces back, Arawn's deathless Cauldron-Born arrived, slew King Math and laid the fortress waste.
Having destroyed one strong point of Prydain, Pryderi sought to make an end of the other as well: the small farm of Caer Dallben, which none of Arawn's forces could safely approach. Challenging the aged enchanter Dallben with a dagger made specially to kill him, Pryderi learned the horrifying truth: just because Dallben had never killed didn't mean he couldn't. A ring of flames had sprung up about the farm, ready to descend if Pryderi stabbed.
Realizing he had been betrayed, Pryderi grabbed for the other object of his quest – the Book of Three, Dallben's mysterious tome of lore and prophecy. Yet the book would bear no evil hand and destroyed Pryderi with lightning.
The name Pryderi derives, as do many names in The Chronicles of Prydain, from the Mabinogion. Pryderi is a major figure in that collection of Welsh legends. The son of Pwyll of Dyfed and Rhiannon, this legendary Pryderi was stolen as an infant by a monster, and found by one Teirnyon Twryv Vliant. However, the child's mother Rhiannon was wrongly blamed for the mishap. As the boy grew up, Teirnyon came to recognize his resemblance to Pwyll, and eventually returned Pryderi to his father, thereby exonerating the mother.
In the Welsh Triads, Pryderi is listed as one of the Chief Swineherds of the Isle of Britain. Here the legendary figure named Gwydion ab Don stole Pryderi's pigs. In the fourth branch of the Mabinogion, Pryderi was killed by Gwydion, engineering a war alongside his brother Gilfaethwy, in order to rape their uncle's hand-maiden.