The Quest Narrative

The quest is a type of story in which the hero sets off on a mission to retrieve some object of value or solve a great mystery. The mission involves many great obstacles and difficulties which must be overcome to achieve an ultimate goal. Standing between the hero and this goal is the villain. The villan (and any villainous allies) must be vanquished before the hero can accomplish the objectives of the mission before triumphantly returning home to claim a well-earned reward.

The theory
The Russian narrative theorist, Vladimir Propp, identified a set of 'character types' typically found in the quest:

The Hero
The protagonist and main agent of change.

The Villain
Places obstacles in the path of the hero. Must be defeated in order that the hero can carry off the prize. Often assisted by henchmen who oppose the hero before the climactic confrontation.

Donor
Provides the hero with a 'gift'. This could be a magical power, a piece of valuable information or a talisman.

Helper
The hero's trusted sidekick(s). Often a dangerous role in quests as helpers are quite likely to find themselves sacrificed to the cause - helpfully providing or strengthening the hero's revenge motive.

Dispatcher
Sends the hero off. May also act as the hero's mentor.

Sought for person
Or 'Princess' - may be the object of the hero's mission and/or the reward for succeeding in the quest.

False hero
Often mistaken for the real hero by other characters (including the princess's father - who may be tempted to bestow the reward on the False Hero instead of the Real Hero).