Karen Eiffel's Typewriter

Origin
Karen Eiffel is one of the main characters of the film Stranger Than Fiction, with Will Ferrel starring and Emma Thompson playing Ms. Eiffel. The story follows the life of IRS official Harold Crick, whose monotonous life is interrupted by a voice in his head, narrating his life. He seeks help from a literature professor, who suspects Crick of being a character in a story and tries to determine if it will end as a comedy or tragedy.

Meanwhile, Karen Eiffel is an author experiencing writer’s block, whose latest dilemma is figuring out how to kill off Harold Crick. When the events she types to Crick’s story become real, she discovers this too late to prevent her from writing Crick’s death. Crick dies courageously saving a boy from being run over by a bus, but she writes him back to life because “if a man does know he's about to die and dies anyway. Dies- dies willingly, knowing that he could stop it, then- I mean, isn't that the type of man who you want to keep alive?”

Effects
Allows the user to influence certain events by typing them out, though they may play out in unpredictable ways. Events are permanent unless the story is rewritten later on, allowing the user to reverse or ‘retcon’ any events beforehand; however, it must fit in with the rest of the story.