That reminds me of two fics but I can only really remember/find one of them. It's incomplete and looks to stay that way but I'll link it anyway, it's No Light Without Shadows by Draeconin (http://www.fanfiction.net/s/7254069/1/No-Light-Without-Shadows). Harry is the heir to a powerful line that gives him some new abilities and he gains a seat on the Hogwarts Board and finds out about it because of Severus (I think) and Dumbledore had been hiding it from him. Hope this is it!