Abstract The 13th-century manuscript Paris, BnF, français 1448 (= D) contains a linking text between Enfances Vivien and Chevalerie Vivien . It can be divided into two nuclei, the first narrating the adventures of a young Rainouart and the second developing the dubbing of Vivien: in both cases, events of the biographies of two popular heroes only hinted at in other major poems, which a compiler decided to narrate extensively to fill the gap in the cycle of chansons on the geste Monglane . This paper, alongside the first critical edition of that text, offers a broad introduction on the literary and cultural features of these two stories (which can be classified as exemplars of the enfances sub-genre of medieval French epic).