Mabon / Maponus / Apollini Mapono

As the Arthurian tales shifted thru different languages/ cultures the name changed from Mabon to Owain to Mordred.

Mabon M. Modron of Mediaeval Welsh Literature is the Celtic deity 'Maponus son of Matrona' - 'the son of the mother goddess.

 Under the Romans Apollo became closely associated with the Celtic god Mabon to such an extent that four out of the five surviving Roman inscriptions discovered in North Britain mentioning the god link the two as   'Apollini Mapono'.

In a poem in the 'Book of Taliesin' Mabon appears as a brother / kinsman of Owain ap Urien, or possibly as Owain himself under a pseudonym. 

The tale of Mabon's imprisonment is elaborated in 'Kilhwch and Olwen' from the Mabinogion. He is stolen from his mother as a three day old babe and Kilhwch /Culhwch must find him in order to be able to hunt the 'Twrch Trwyth'. 

Bedvyr /Bedivere and Kai rescue him, after the 'Oldest Animal' - 'The Salmon of Llyn Lliw' identifies his prison as Caer Loyw

"'Mabon' - 'boy' is applied to Christ, but the 'Mabon' of M. Welsh tradition derives his name from that of a Celtic deity 'Maponus son of Matrona'" - Bromwich