There are, as said before, different levels of WCA, or rather awareness that what we do is not our own will.
For characters :
Level 0 : Has no idea what is going on and live his or her life, having adventures and such.
Level 1 : Someone who is fated to do something. He or she knows that doing this is inevitable "according to the prophecy".
Level 2 : Author aknowledgement. The characters can interact with the author, mostly by words (or in some comic, with the Author's avatar).
Level 3 : Aware they are in a comic. This is where most of the fourth wall breaking comes in. Talking to the audience and such.
Level 4 : Interracting with the readers or the readers avatar. This is the level where boundaries are lost and where most of the crossover wars went after the inclusion of the forums.
Level 5 : Manipulation of the comic in Author-like way : Catnap and the Editor.
What..free publicity cannot harm anyone...right?