I think that Dudley got really creeped out about what he heard about voldemort, and having first hand experiences with dementors makes him realize how much danger he's in. then he thought about harry, whom he had always had a tiny bit of affection for. I think being "better" than harry always boosted Dudley's confidence

I was very surprised and touched by Dudley's attitude toward Harry in DH.

JKR explained in her Bloomsbury webchat on 7/30/07, what Dudley saw during the Dementor attack:

That is why Dudley changed how he felt and acted toward Harry in DH.

I felt that he started to appreciate Harry for saving him from the dementors. That incident most likely destroyed his prejudices about wizards and helped him overcome his immaturity towards Harry. In the end Dudley grew up and realized that one of the Dursleys should give some thanks to him.

I wondered that, too. Someone had to let the Dursely's know Harry was safe and won the war so they could leave the protection of the Order. Maybe they got to have one more chat after all.

I hope when JKR does the encyclopedia she will put in what happened to the Dursleys, too.

I agree. No matter how much Dudley semmed to have hated Harry, deep down he probably liked him. They grew up together and lived under the same roof(only the summer,for Harry)for 16 years. Imagine,a person living with you that long, and then you're told that you probably won't see that person ever again.Shoking, I would say. Yes,I would also say that Dudley's likin for Harry also grew when he saved his life.Deep down,he must of felt some gratitude.

I really hope that Harry went to go visit them after it was all over.

I'm so happy that Dudley finally shows he isn't completely like his parents!

i think it was just after harry saved his life

I think Dudley would have liked Harry from the beginning, ifit weren't for his parents. He grew up prejudice against Harry and his kind, and never was able to form his own opinions about wizards. Seeing Harry leave, and all the trouble wizards were going through for him, made him realize that his parents were wrong.

Katie

I am sure that Dudley loved Harry since they grew up together. Dudley did not know a life without Harry in it. I feel like he acted that way toward Harry because of his parents, as it was learned behavior. I really feel that things changed between them after he saved Dudley. For Dudley it was like losing his brother, and not understanding why he wasn't going to be there any more. He has never known a life without Harry in it, even though those moments weren't warm and fuzzy, they were always in each other's lives.

I wished JK had written that Dudley produced a magical child, and was on 9 3/4 sending his child off to Hogwarts at the same time as Harry. That would have been to funny.

Well I have to admit that Dudleys reaction to Harry being seperated from the Dursleys surprised me. I think that Dudley changed somewhat when Harry saved him from the Dementors. I mean think about it, he was brought up to hate and belittle Harry every chance he got. His parents made sure that both Harry and Dudley knew that magic was a bad thing. After all they weren´t even allowed to say the word in the house. I don´t even want to think about what grisly stories Petunia told her beloved Diddykins about the bad bad witches and wizards and the horrible things they could do. And then the first (at least the first we know of) experience with magic he has is that Harry sets a Boa on him.... and the first real wizard Dudley meets is Hagrid who promptly gives him a pigs tail and he needs to go through a operation to get rid of that one... how humiliating is that!?
I is clear that that experiance didn´t make him warm up to magic.
The sweets from the twins didn´t help either (though that scene was very funny indeed ). And then Harry goes and saves him, now that must have been a shock for him. But he starts to realize that not all magic is bad. After all Harry used some of it to save him. That might have led him to the conclusion that Harry is not that bad a person all together...
Well that at least is what I think.

i really liked that bit. but i still dont think he had much respect 4 him b4
i think it was probabaly bcos harry had saved his life from da dementors

I wonder if Harry kept in touch with Dudley or if Dudley tried to sort of mend their relationship after the war once they were brought back to Privet Drive. Would be kind of good if they had a sort of understanding kind of like Harry and Draco.

I think that it was always there but he saw how mean is parents were to Harry so he thought he would be to and when he finds out that when Harry leaves this last time he might never see him again and that is why he was being so nice to him.