Before I drew Mr. Sin's first appearance, I spent a lot of time (and pencil lead) trying to get his character design "just right." It's funny... you think you have a perfectly clear vision of a character in your mind, but when you actually sit down to draw him, you realize you don't actually have the foggiest idea about how he is supposed to look.
I settled on Mr. Sin's gangly body and elongated limbs right away, but his head was another story. I wanted him to have a simple face that was capable of both goofy exaggerated insanity and legitimately frightning anger... a face that really emphasized his erratic shifts in mood and demeanour. It was hard to do! Sometimes you just have to work it out by going through pages and pages of experiments until you stumble across that one design that captures the feeling you had in the back of your head.
Anyhow, if you are interested in this sort of thing, you can have a look at all my concept sketches for Mr. Sin by clicking the image below: