Sam had a brother and a sister in the books. His mom came out (when all the shifters did) and his stepdad shot her. Tara did have a thing with the vamps though in the books, just not quite the same. I don't really care about her story on the show.
It'll be interesting to see what they do with Jason since they didn't turn him into a panther. The whole Hot Shot thing was much better in the books I think. I have to see what they end up doing with Crystal and the rest of them.