Fflewddur has a magic harp that will break everytime Fflewddur tells a lie or colors in the facts. His catchphrase is "Great Beelin!", the witch Orwen has a romantic interest in him while Orgoch wants to turn him into a frog and eat him. Fflewddur, however, has his moments of bravery such as when he stands up to the witches so that they will revive Gurgi. Though not specified in the film, in the books Fflewddur is a king of a rather small kingdom and generally prefers to travel as a bard across Prydain.
Fflewddur first appears in the film in the dungeons of the Horned King being menaced by a pair of chained attack dogs. He is freed by Eilonwy and Taran and joins their escape from the Horned King's castle. Afterwards, Fflam is attacked by Gurgi, but the latter turns away after he realizes Fflam is a friend of Taran, who he likes. The four of them proceed to Morva, where they encounter three witches, one of whom is in love with him. After the new team realizes they don't know what to do with the Black Cauldron, he is ultimately recaptured by the Horned king, but he escapes again.
In the original books it's specified that "Fflewddur" is his name while "Fflam" is his title.
Also, in the books, he is shown to have a long, pointed nose and spiky blond hair, and is implied to be years younger than his animated counterpart.