Wow! Another emotionally charged and action-packed installment in this series. Apollyon picks right up where Elixir ends and we learn many new details regarding the two Apollyons, Lucian's plot, the gods involvement, and lots of feels from the "gang of nine" While Apollyon doesn't have quite the intensity of Diety, it is a great setup for Sentinel, the final book in the series. 
 And although Aiden is incredibly swoon-worthy, I've got to say that Alex is the star for me in this series. She deals with a whole world of crapola in Apollyon and does it well. Even though her feistiness takes a few hits, her core values remain intact. I'm really hoping that Alex and Aiden get the happily ever after they have both been dreaming of, but its still a long and dangerous road to get there. *sigh* 
 And kudos to Jennifer L. Armentrout. She really knows how to tell a story-- when to give the reader information, when to withhold, and most important to me, is letting the reader feel the myriad of emotions right along with the characters.There is a subtle depth to her characters and her writing that keeps me coming back for more.