In Guillem de Torroella’s short narrative poem La Faula (ca. 1370), a Catalan squire from Majorca embarks on a journey that takes him to the island to which Morgan and King Arthur fled after the defeat of Salisbury. The well-read poet-protagonist will discover an ailing king, surrounded by his sorrowful sisters Love and Valor, before he is ordered return to his land to explain the moral and political implications of the scene he has witnessed. This allegorical revisitation of Arthurian materials is structured by bilingual dialogue, as the characters and marvelous animals that inhabit the enchanted island speak in “lengatge frances” (v. 194). Multilingual dialogue and linguistic interference in La Faula reflect cross-fertilization between French, Occitan, and Catalan narrative traditions. Written in Occitano-Catalan and broken French by a poet from Majorca, and further Catalanized by scribes, Torroella’s Arthurian travelogue provides exceptional evidence related to the functions of literary French in the multilingual Crown of Aragon, allowing comparison with other border-crossing languages within the late medieval Aragonese Empire. At least three romance vernaculars were in competition in written culture: whereas Occitan remained the dominant language of lyric and narrative poetry, a parallel narrative prose tradition emerged in both Aragonese and Catalan. In this triglossic vernacular context, code switching between languages or language varieties in written texts performed a range of functions, from register variation to intertextuality. This paper intends to examine some of the ways in which code switching between a hybrid Occitan koine and French, combined with ekphrastic mise-en-abyme of Arthurian romance affords insight into the particular functions of French in Mediterranean territories that were subject to Crown of Aragon.