Son of Tristan and Isolde (Isoud La Blanche Mains) in Spanish romance as well as the Italian I Due Tristani.
He was born, along with a sister named Isolde, during Tristan and Isolde’s sojourn at the Castle of Tears. He was raised by foster-parents. Mark, who thought him the son of Isolde of the White Hands, crowned him king of Cornwall. Arthur knighted him and gave him his father’s former Round Table seat. He enjoyed the protection of a sorceress named Sergia.
Guinevere and the Queen of the Amazons became infatuated with him, and the latter forced herself upon him with enchantments. He eventually entered the service of King Juan of Castille and married Juan’s daughter, Maria, whom Tristan saved from Moors (Saracens).
Source
I Due Tristani | 1555