Define your chosen character in terms of
whether he is the protagonist (hero), antagonist (villain), supporting player (a
helpmate of either the hero or villain) or a catalyst. A catalyst character
(also referred to as an agent for change) often does not participate directly in
any of the action, but instead fulfills the role of inspiring the lead character
to take up a cause or quest he might otherwise not have pursued (for example,
Spider-Man's kindly uncle who gets killed early in the story would fit this
definition).
