I think Zuko's shy smile at seeing Hakoda safe with his family is partly him allowing himself to share in the satisfaction. God knows he's never going to be able to save his father, but this is pretty close.

I've never thought about how it might relate to his own father before, even though it does make sense. That scene totally had me thinking about Zuko's mother, mostly because she fits more with the kind of parent that Sokka and Katara got back, even if she's his mother and not his father. If he ever thought about himself saving one of his parents like they did Hakoda, I think it would be her. I can just see a young Zuko, confused and trying to adjust to what happened to his mom when no one will tell him anything, coming up with all kinds of explanations in his head (like she was kidnapped by bandits or something) and maybe imagining himself rescuing her.

We had better find out what happened to her in one of those last few episodes.