Francesca is François Prelati, the friend of Gilles de Rais from the time of Jeanne d'Arc. As Gilles eventually strayed down a dark path that led him to try summoning a demon to relieve his financial difficulties, Prelati was the actual magus in their twisted relationship, with Gilles merely being the patron.

Originally male, Francesca has died numerous times and changed bodies, but the first death ended with her recorded as a Heroic Spirit. The Heroic Spirit version has no memories from after that first death.