Mephisto: I like the pickpocket one, and the "normal-looking" one is good too. So is "tired and occult", actually.

Alto: Probably your favorite's the one I'd go with, though the short n soft one could work too. For reasons :P

King: Not a fan of any of these. If I had to pick one, though, I think I'd go with the action one. 

Clara: I've always pictured Clara to have black hair and red eyes, making the red eyes Clara my favorite. Ethereal Clara (bottom one) is a close second though. Demon Clara and "occulty schoolgirl" ain't bad either.