We present a study that investigates the heretofore unexplored relationship between a player's sense of her narrative role in an interactive narrative role-playing game and the options she selects when faced with choice structures during gameplay. By manipulating a player's knowledge over her role, and examining in-game options she preferred in choice structures, we discovered what we term the Mimesis Effect: when players were explicitly given a role, we found a significant relationship between their role and their in-game actions; participants role-play even if not instructed to, exhibiting a preference for actions consistent with their role. Further, when players were not explicitly given a role, participants still role-playedthey were consistent with an implicit role -but did not agree on which role to implicitly be consistent with. We discuss our findings and broader implications of our work to both game development and games research.