To substitute an individual in most intimate proximity and to play sexual masquerade between the sexes appears to have been a global narrative pattern of various genres. The following considerations though are neither concerned with a widely noticed phenomenon of narration in general nor with the variety of comparable variants in respect to form and content but they are concentrating on a particular practice of narrative transformation. In ›Prose Lancelot‹ the dual substitution of Ginover touches the central meaning of an adultery love between her and Lancelot. It is reflecting the conflict of clerical and courtly discourse characteristic for ›Prose Lancelot‹. The substitution as narrative core is confronted with courtly, biblical and novellistic patterns of narration.