One of the things I enjoy about role-play are the unexpected things you can learn when trying to enter a character's frame of mind. I have mentioned, I'm sure, that there are things you don't know about a character until you're actively RPing with them and figuring out their reactions.
I quipped to one of my friends that I was "stress testing" a character when she agreed to do some RP with me with a new DK I'm playing for a storyline. I think that can be an apt term, as I was learning what strengths and weaknesses I had while playing Dearnly. I was trying to test what did and didn't work with him and discern any quirks the character may have. About half way through the "test" I was surprised at a reply Dearnly made; how odd it is, to be the author of a character, and yet be taken by surprise at his actions.