I think what Len said about viewpoints is equally valid about characters --
they are story driven. They have a specific obligation to the story: add
some color, illuminate another character through dialog, or advance the
plot in some way. Many of the characters in a linear story have simple
roles and are therefore very simply defined. Woe to interactive authors if
we can't figure out how to have simple characters as well.
A hierarchy of characters can be envisioned where the various levels of
characters (subclasses?) are defined by the complexity of the role . For
example:
Level Capabilities
-----------------------------------------------------------------
Extra Background role, canned behavior, no dialog
Color extra Background role with dialog
Bit player Plays a noticeable but unchanging role in the story
Supporting Plays a role which changes as the story develops
Lead Drives the story
I'm sure such definitions have been around since Aristophanes, perhaps a
more formally schooled student of theater could point us to the standard.
The challenge of making characters interactive is different at each level.
Bit players in particular interest me because they seem to be on the cusp
of complexity. Extras will always be simple while lead characters will
always be complex. A linear bit player can be very simple, but how simple
can an interactive bit player be?
Michael
