Secondary Character

[LadyNemo]

So the rulebook mentions that you can have a secondary character. My question is, are you limited to playing one character per event? What I wanted to do was to play a secondary character on Friday night, and switch to my current character for the remainder of the event. The only mention I found in the rulebook about switching characters was for if the character you were playing died. Also, if you can only play one character, do you need to specify somewhere which one you are going to play?