Mabon's name and relationship to Modron point towards an older divine tradition. Scholars connect him with Maponos, the Brittonic Great Son, who is attested in Roman-period dedications under the name Apollo Maponus. An altar from Corbridge records such a dedication by a Roman military officer. That inscription is evidence of worship, not a record of the medieval imprisonment story. Maponos belongs to the discussion of Mabon's background rather than being proof that every detail of the Welsh tale preserves an ancient religious ceremony.

The Welsh poem Pa Gur remembers Mabon son of Modron among Arthur's warriors and associates him with Uther Pendragon. The triadic tradition places him among the Three Exalted Prisoners. These brief references present different aspects of his reputation rather than a complete chronological biography. His fullest adventure is in Culhwch and Olwen, where Ysbaddaden makes his recovery one of the conditions for Culhwch's marriage to Olwen. The reason is practical within the impossible quest: Drudwyn is needed for the boar hunt, and Mabon is the huntsman required to handle him.

Arthur's searchers turn to creatures whose memories extend far beyond a human lifetime. The Blackbird of Cilgwri, the Stag of Rhedynfre, the Owl of Cwm Cawlwyd and the Eagle of Gwernabwy cannot supply the answer, but each helps carry the inquiry onward. At last the Salmon of Llyn Llyw knows of a prisoner whose cries can be heard near Gloucester. In Lady Charlotte Guest's translation, Cei, the Welsh figure known as Kay, and Gwrhyr ride on the salmon for the first inquiry. They hear Mabon identify himself and say that his release must be won by fighting rather than wealth.

The rescue is a separate visit. Arthur brings his warriors to attack the stronghold, while Cei and Bedwyr, the Welsh counterpart of Sir Bedivere, approach on the salmon. Cei breaks into the prison and carries Mabon away on his back. The distinction matters: Gwrhyr helps discover the prisoner, while Bedwyr accompanies the assault. Mabon leaves captivity and returns with Arthur, no longer merely a name that the oldest animals struggle to remember. The tale does not identify his captor or explain exactly how long he has been imprisoned.

Mabon's role becomes decisive when the hunt reaches the Severn. Riding Gwyn Myngddwn, the horse of Gweddw, he takes the razor from between Twrch Trwyth's ears. Cyledyr obtains the scissors, while the comb is recovered later in Cornwall. The rescue has therefore restored a participant whose particular skill matters to the wider company. Scholars have compared Mabon with later romance figures such as Mabonagrain, Mabuz and Nabon, but those comparisons should not turn separate characters into one continuous life. Mabon's own Welsh story remains the recovery of the Great Son and his return to action.