As I mentioned to someone else, I don't think that the S2 characters really are 'different' to the S1 versions. True, there is a slightly different emphasis in skill areas, and cosmetic changes such as clothes and hair, but I still believe that for the most part they are the same characters with more or less the same background experiences as we saw them having in S1.

I believe it's been stated by AH that they are the same people with most of the same experiences, just slightly different (obviously, they cannot be one-hundred percent the same, since none of them knew Claudia, etc). But they're not meant to be substantially altered from the characters in S1 that we know and love.