Similar to style, I guess ... I've not had that many problems discovering my main character's voices, their thoughts and accents are pretty much in place and came almost naturally from the start but I have one character (who appeared sporadically) in the first book but is set to be a bigger part of book two. The trouble is, I just can't pin him down in the speech department, I really don't know what he sounds like. His sister speaks Italian when she's emotional (for any reason) but I just can't see this character being like that, although on one occasion, he spoke to her in Italian because he didn't want a third person to understand the conversation. I think I'm unsure as to whether or not he would use slang terms. How do you figure out your characters when one just won't fall into line?