Renton didn't really bother me really, maybe yelled at him a bit when he said stupid things to Eureka but other than that. Did you watch with Subs or Dubbed, since that might have made a difference too.
SPOILER WARNING, SPOILER WARNING, YOU HAVE BEEN WARNED!
I have to say I loved how much he had changed by the end, and Eureka as well for that matter. When he woke up after getting over his fever and told Eureka that she was beautiful even after her changes I was so happy. That is when you know he had reached the point of unconditional love. I actually think he reached that point before then, his willingness to mutilate his own arm to show it didn't matter to him what she looked like as long as they were together.
I get a little upset when people complain about Eureka's changes. She starts out with very little emotions but by the end has a full range of emotions. People complain that she was weak by the end but forget to realize that she is merely having to deal with all the pain from what she did in the past. Look at how bad Renton was after he realized he had been killing people and she had killed so many more. By the end they had both changed because of each other and realized that they loved each other.
I also thought rather highly of Renton when he had filled out the adoption form for the kids before he left to get Eureka. Someone that young willing to do that again shows how much he changed from the beginning. And its not just that he loves Eureka, he has come to love the kids as well. I liked it when they say they want their papa as well as there momma to come back as well. This series was filled with emotion.
Sorry for my rambling, I have to love the love
