Huh. Cryoburn wasn't my favorite, but I loved CVA. And I'm curious as to why you think Ivan had no stake in the situation and didn't have to grow and change to deal with it. His stake was Tej, whom he was falling in love with and didn't want to lose, and he definitely grew and matured emotionally through that--I don't think at the beginning of the book he'd have been willing to actually let himself love her, so much. Fun, yes. Commitment, no--he'd grown so stuck in his commitment-phobic ways. He was stuck in a lot of ways at the beginning of the book. Not unpleasantly stuck, just ... sort of existing in a nice pleasant life with a nice pleasant job and nothing to either tie him down or challenge him or ever make anything different, and very alone in that. Stuck in a rut. And at the end, he's still got a pleasant job and a pleasant life, but someone who gets him and has the same lack of ambition. He's not alone anymore, and he's not stuck in a rut anymore.

True, he was adjacent to the main action rather than driving it, but this is Ivan. He's not Miles! He's made a lifetime out of staying out of the action! It would have been wildly out of character for him to be the center of events.