A discussion of who each of these characters can be found in the Character Analysis section of the enotes study guide. (Click on "Character Analysis," and then start with Valjean. Then read the discussion of the other characters. Those sections will sum up the characters and the relationship between the two that concern you most.
As for the forgiveness, I think you're talking about the Bishop's choice to give Jean Valjean a second chance. That's discussed in Themes section of the enotes study guide.