Never saw the ending coming but at the same time I wasn't surprised either. Nick finds out that it doesn't matter how well you set yourself up in his world, all the money and status doesn't deter everyone, especially when others have their own agenda for you.
Initially thrown by the telling of Nick's early years, it did make sense to have this revealed now. The ending uncovers more of Nick's ongoing plight to rid himself of the demands / heritage that prevents him from living the life he desires.
Thought I was being clever with this series, leaving it long enough to read the books one after another, but there is obviously a book #4 to devour :)