Role-playing is hard

I have an admission to make - I can't play the evil guy in RPGs. I simply cannot. I think I first realized this in Knights of the Old Republic when I tried to do a play-through of the game as sith, see how the storyline works out if I do so, and see an alternate ending. Now it is usually quite obvious what the evil (or "dark side" or "renegade") options in these games are, making the whole task trivial from an intellectual point of view. Emotionally, however, I just couldn't bring myself to be such a dick to the NPCs, even knowing that they were just a collection of pixels. (Or, more accurately, bits.) Somehow, Bioware RPGs seem to immerse me so much that I can't actually - you know - role play. While I'm not thinking about the player character as myself, I will always behave as if it was myself in that situation.
(Warning: The paragraphs below may contain very slight spoilers for Dragon Age: Origins.)