headcanon/mini-write time!
katara knows exactly how she feels about a person and knows what she wants and will act accordingly to fulfill that want. so it's a bit of a surprise for her to realize that, after their "life-changing field trip" together and him trying so hard to earn the trust he had foolishly lost before, katara likes zuko. she "wants to hold his hand all the time" likes him. she "kiss him whenever she damn pleases" likes him. she "you mean so much to me, more than I ever thought possible with a person, and while I could live my life without you, how could I when all I want is you by my side" likes him. katara realizes this...
and never acts on it
well, she kind of does. little hints like watching him whenever he wasn't looking, a special smile that belonged only to him, finally allowing the inevitable connection that existed between them since being trapped under Ba Sing Se to come alive. you know, the most obvious signs ever!
(who was she kidding. she was just scared. their friendship was still so fragile and new. maybe one day in the future, when the war is over and won, katara will tell zuko exactly how she feels...)
after spending his entire life freely giving his love to a family who, for the most part, probably didn't deserve it, zuko was surprised to realize that that part of him wasn't burned away like he thought it had alongside his face. instead, it made a thick exterior to protect itself, but that love was still there and so much a part of him that it was only natural it would eventually extend to every member of the gaang
but it was different when it came to katara. yes, he knew he loved her like everyone else, but it wasn't the type that grew from the camaraderie that he had with sokka, or the type that came from having someone like a sister who wasn't going to kill him. all zuko knew was that everything he did with and for katara was done out of this special love. he wasn't oblivious to his own feelings, not like before. but he had no way of putting them into words, so he could only hope that his actions would speak for him
(it was so natural and easy, there was no need for a second thought, or even a thought at all, to show how much zuko loved katara. maybe that was why there had been no hesitation on his part to take the lightning to his chest for her. he was filled with so much love for her that he could not fathom a world without katara in it and with no way to give his love to her with every breath)
