OPIS
Requiem for an Assassin is a great example of an author trying to find a way out of a characterisation cul-de-sac that he has gotten himself into and only being partially successful in his attempt at doing so.
At the end of the previous John Rain thriller, titled The Last Assassin in the US, Eisler's half-American/half-Japanese assassin had finally put behind him the never-ending (and slightly tedious) saga of his affair with the Jazz pianist Midori and returned to the arms of his Israeli lover Delilah. With an affirmed friendship with ex-Marine sniper Dox in place and the death of a dangerous old adversary it appeared that Rain was finally changing his self-imposed isolated lifestyle for a more normal one with long term human relationships, even if he wasn't giving up the business of killing.
With Requiem for an Assassin however, it appears that Eisler somewhat regrets humanising Rain in this fashion. Although when we pick up his story he is still with Delilah, living in Paris, it is rapidly revealed that Rain is having difficulty dealing with his new lifestyle. When Dox is kidnapped by another face from his past, ex-CIA spook Hilger, in an effort to coerce Rain into undertaking some wet-work, it is the perfect excuse for the old, emotionless killing machine (the Ice Man as Rain refers to that side of himself) to resurface and get back into the action.
All of which feels like something of a cop out. Over the previous novels in this series Eisler has managed to slowly humanise John Rain in a way that has always felt real and logical. There's been no road to Damascus conversion; the man has always remained a killer, but in increments Eisler has allowed Rain to grow and form long term attachments. With Requiem for an Assassin however, it feels like Eisler regrets allowing this to happen and has sought a way to bring back the Rain of old; the one man killing machine of the earlier novels. The result is not only a somewhat contrived set-up but also a step back in terms of character development.