Here's one of the first lines I ever wrote for the character of Cordelia on Buffy:
CORDELIA
I do well on standardized tests.
(off their looks)
What? I can't have layers?
I was so tickled with that line, and completely delighted when it actually made it into the final episode. I just love those moments of unexpected revelations of character. This one was done with purposeful obviousness, for the sake of the joke, but it got the job done anyway.
Come up with the main traits first. You don't want "contradictory" to be the only thing that shines through. Figure out who this person *mostly* is. Then add some arrows jetting off in other directions. I bet you'll get interesting results right away!
Lunch: wonton soup from Noodle Planet.