When I read through the diary endings, I realized that sometimes the characters sound a little too much alike. You caught Jolee's speech mannerisms pretty well and I could tell it was him. Jacen, Darius, and Revan should sound different from each other, and right now I feel like they all sound a little too much like Jacen, if that makes any sense whatsoever. I don't think you'll have to do much to achieve that, however--slightly different speech mannerisms maybe? Slightly different vocabulary? Wish I had an intelligent suggestion for you on that. I have to go research that one myself, because now it's going to drive me nuts til I can learn just what the correct literary term is.
I had fun reading Jolee's little comments.