The character appears in the Tale of Taliesin, where he is depicted as the son of Ceridwen and Tegid Foel, and is given an extremely beautiful sister named Creirwy.
In later versions of this tale his characteristic ugliness is transferred to a brother, Afagddu (Middle Welsh: Avagddu; from y fagddu, "utter darkness"), though Ifor Williams suggested this name arose as a nickname for the famously gruesome Morfran.
[2] In the story, Ceridwen tries to help her son make his way in the world by creating a potion whose first three drops would bestow the drinker with knowledge of the future.
She gives Gwion Bach (the bard Taliesin) the job of stirring the brew; he splashes three drops on his fingers and licks them, whereupon he gains the knowledge intended for Morfran/Afagddu, who remains ugly and despised.
[3] Scholar Caitlin Green further suggests a connection with the character called "Osfran's Son", who is buried at Camlann according to the Englynion y Beddau (Stanzas of the Graves).