A Computer-Controlled Character (or CCC) is essentially a player such as yourself. Their decisions are determined, though, by the Avalon computer rather than a human mind. The technology does not yet exist to allow fully intelligent interaction with a computer and Avalon does not pretend to do this. However, the CCCs do pertain to hold some limited intelligence: they have the capacity to store and remember events that have concerned them; they have the ability to evaluate the actions of those around them, and furthermore to act accordingly. They have allegiance towards certain people and have certain goals which they seek to achieve.
A CCC is usually easily recognisable as it will often have a title or even a proper name. A CCC is a personality within the game that has a more specific role than most other computer-generated beings and as such you will find it rewarding to interact with them. Greet CCCs (or enter REQUEST QUEST FROM <CCC>) whenever you meet them for they usually know of great quests which you might be able to perform.