Would either happen with so much speculation about them both? Will there ever be a relationship or just the hint of one?

I am for Katara and Zuko myself. Aang is just a boy, uncomplicated and his story appears to be based in coming to terms with who he is and his destiny, whilst being a kid. A destiny he wouldn't be able to achieve without the support of his friends. (Sort of like Harry and Hermione).I imagine the relationship he has with Katara will be stronger for them not being involved.

And Katara is his best friend. She is his support. Not really a relationship that has its basis in anything romantic, particularly considering her overwhelming sense of responsibility for him. There is no tension there, no spark, but more of a comfortable easiness and security. And yeah, he'll grow up but she already has.

Zuko is far more passionate, disciplined and mature. And there is just such dichotomy in their differences; sun/moon, fire/water, life/destruction. Yet fundamentally they are similar; faithful, persistent, idealistic, with an innate sense of justice and integrity. Their similarities and opposites mean they effect one another on such profound levels.

He disturbs her, threatens her and challenges her. All of the things Aang doesn't. She has such a wealth of preconceived notions and Zuko challenges all of those whilst being someone she is not responsible for. He is as passionate as she is and she can't pigeonhole him.