While I appreciated the mystery elements when I first read the series I didn't tie it into activism. The power that the characters wield comes through "unofficial networks" while the media or government officials tend to be corrupt. As the books continue Nel points out how the question of power becomes more complex as characters explore the morals of power positions and the exercising of authority. When Harry chooses not to kill Pettigrew after learning he killed his parents, there is the morality of Harry's choice that makes his decision more complicated and wrought with emotion.
I particularly liked how Nel articulated the ambiguity of the characters in the books. It is one of the appealing aspects and gives characters more complexity. Even Severus Snape, who seems like a one dimensional villain, shows depth by the last book. There is no index in the book and it is short, only 96 pages. If you are teaching the books or having a book club then it would help with discussions.