Nick Montfort argues that the contentious notion of the "player character" usefully constrains and makes possible the player's interaction with the gameworld. He considers the possibility that in interactive fiction one plays the character (like an actor plays a role) rather than playing the game.
The source is the essay-review on www.electronicbookreview.com written by Nick Montfort
The quote defining the "player character":
"In interactive fiction, the "player character" is that character who the interactor (or player, or user) can direct with commands. The first example of interactive fiction, Will Crowther and Don Woods's Adventure, instructed the interactor: "I will be your eyes and hands. Direct me with commands of 1 or 2 words." In Adventure this I may seem to be the same as the narrator (Buckles 1985, 141-142), but the development of later interactive fiction has made it clear that this entity - the "eyes and hands" that focalize the description of the interactive fiction world and the narration of events in it, and the agent that the interactor can direct or command, through which the interactor can influence the simulated world - is best considered as a separate entity, the player character."
"For interactive fiction to succeed, the player character must, in some sense, fit within the interactive fiction, and the interactor must fit within the player character."
All quotes were directly rewritten from the essay.