I set my eyes on Cain the moment I read "The Catalyst", so no doubts I would have loved this book focused on him. Cain and Tam were such a perfect match that it was practically impossible not to enjoy the reading. Their relationship is rich of many intense moments and funny ones, but what's really unique is watching them getting closer more and more thanks to that deep sense of solitude the both of them experienced through all their lives (and we're talking about a very long time). In Tam's case she's so desperate and feels so alone that she's ready to face death to finally put an end to her solitary life/eternity. It takes great courage (even if this death would have been a hell of a pleasurable one) and if you put yourself in her shoes, you can only be touched in seeing how hard the absence of a mate is.
Usually you dislike at least one or two characters in a book, guess in a series, but in this one it's hard not to be intrigued by everyone and almost impossible not to like every single couple. You can probably be upset with the villains... Well, actually you might cheer someone in the dark path... See? There's no way out. And the most amazing thing is that it doesn't matter if you previously read about them or not, you will fall for them anyway.
Father Adrian, I'm so waiting for you next...