How do you know who you are when you become a fictional character? Le Bureau des légendes, the spy series, faces us with this question: can living “under a legend”, that is to say under a false identity that shakes the foundations of the self, create identity-related disorders? Who are we when we live several lives? Guillaume de Bailly, the main character of the series, discovers who he is through the different roles that he plays. I will look at the boundary between fiction and reality by making a comparison with Philip Roth’s narrative device which makes use of alter egos to better portray himself. Through these two works, I will explore the question of authenticity in the sense given to it by Jean-Paul Sartre, but also that of the relationship of trust between the creator and the spectator-reader: where does fiction end and where do lies begin? And what if fiction revealed something truer than reality?