how do you do a character continuum?

ex. good/evil

This is difficult, as varying folks have different ideas of what is good, and what is evil.

Here are one persons thoughts on good and evil.

http://sprott.physics.wisc.edu/pickover/good.html

Here is what I suggest: look at those traits in the evil guys, and the traits in the good guys. See if you can make a scale of those traits, then overlap them in opposite directions. Sometimes the most evil guy can show some kindness, and vice versa.