Sandbox / Audience Surrogate

Nikki Reed (Rosalie Hale): So, Kristen, there must be something really special about you for Robert to take such a liking to you and risk the lives of his entire family. Tell us about yourself.
Kristen Stewart (Bella Swan): Me? Oh, no. I'm just a hollow placeholder for all of the teenage girls in the audience to project their personalities onto. I have none of my own whatsoever.

The audience surrogate is often present to help the audience identify with a character within the work. The immersion supports the Suspension of Disbelief, and the audience feels a strong sympathy to those characters, often facilitating a Protagonist-Centered Morality. To create an audience surrogate, several techniques are available:
  1. The character is responsible for providing the audience with the story.
  2. The character asks questions of the other characters to clarify their thoughts.
  3. The character says things the audience would say.
  4. A character who the audience (or the children in the audience) doesn't just sympathize with, but are supposed to actively see themselves as — by desire, by default, or by author inference.

This trope is about the last one, as the other three have tropes of their own.

Compare Sliding Scale Of Viewer Intelligence.

This trope is broad enough, several subtropes have evolved from more specific usage:

This trope is also related to Escapist Character and Otaku Surrogate.
http://tvtropes.org/pmwiki/pmwiki.php/Sandbox/AudienceSurrogate