Rewriting romance does not always go to plan. One example of how adapting popular romance tales can produce complex and ambiguous results can be found on fols 125v–129v of the fifteenth-century compilation manuscript British Library Cotton Caligula A.ii. These folios contain the only copy extant of Chevalere Assigne, a remarkably short adaptation of the medieval swan children story. The closest cognate of this 370-line alliterative version of the narrative is the Beatrix version of La Naissance du Chevalier au Cygne, the first part of the Old French Crusade cycle, which runs to 3,196 lines and provides a prequel to the more famous tale of the Swan Knight.

The plot is a compelling one, incorporating themes of transformation and retribution that bridge the generic boundaries of folktale and romance. However, the English version of the story is no straightforward retelling of a familiar tale. Rather, the late fourteenth-century Chevalere Assigne represents an intriguing endpoint to a process of adapting, shortening, and reframing a distinctive storyline. The fact that the central images of this heavily abridged verse adaptation have remained recognisable from when they are first known to have been recorded in the twelfth-century Latin prose Dolopathos neatly illustrates the persistence of romance ‘memes’. Such persistence is a capacity that Helen Cooper ascribes to the ability of these literary motifs to ‘replicate faithfully and abundantly, but also on occasion to adapt, mutate and therefore survive in different forms and cultures’. Many of the romance memes Cooper discusses can be found in this poem: the supernatural, the protagonists of mysterious birth, and the clash of good against evil are all central to the tale. Moreover, the scheming of the evil mother-in-law who has the swan children abducted, their mother's role as a falsely accused heroine, and the fortuitousness with which the abandoned children come to be raised by a hermit are recognisable building blocks of an archetypal romance narrative. These combine with the dramatic final scenes, in which God leads the young hero to victory in battle, to create that sense of familiarity that Cooper asserts can turn a good story into ‘the most mind-engaging form that there is’.