you made him even more scary, which I used to think was impossible

Fufufu, it's all just collected bits ans pieces that others have tried with his design ^w^ A lot of his 'charm' is based on how old he looks, strangely enough- In some visions of him there are tons of extra lines and stuff around his mouth and jaw and it makes him look like even his most neutral expression is 'enraged'. Then when he really gets mad you can imagine just how impossibly wrinkled up and scary his face gets. In a nutshell the best way to express anger is wrinkles around the mouth and nose, and Akuma(when done right) has these wrinkles all the time.

I guess he's just angry all the time. XD

Mweheheheh, yes

Funnily enough, I was thinking this was Urien from SF III :0

I do draw him and Akuma similarly, though I've only drawn Urien once and I haven't yet uploaded that work ^.^