Meme time?

Here is an interesting meme seen about my flist:

Pick a character I've written and I will give and explain the top five ideas/concepts/etc I keep in mind while writing that character that I believe are essential to accurately depicting them.

(Heh, I expect that I'll have to kinda backwards-engineer the answers, since in most cases I don't consciously think about it that way while I'm writing; I just "know" what the character would do in any given situation ...)

My original or fannish characters are welcome here. :)