.. this is the first or second doodle I ever did for the Joker design... initially, there was the idea floating around that the Joker could be decked out as a 'mad scientist'. Also, I wasn't sure how far Eidos was trying to push the Joker's gruesomeness, so I did a few tries with the heavily scarred and torn mouth, but there was too much of a resemblance to Heath Ledger's Joker, so we eventually went a different route.
This is the process I absolutely LOVE about design in general: the exploration of ideas... just throwing ideas at the wall and seeing what sticks, BUT like I said before, the Joker was one of the hardest designs to nail down.