During an Avatar Marathon some years ago, Nickelodeon had tidbits about the show appearing on the screen throughout each episode. I think it was the first episode when Zuko arrived at the Southern Water Tribe that the caption of "Zuko was originally intended to be Katara's love interest" appeared. Zutara fans didn't make that up:
Nickelodeon did. Even their comics loved to tease Zutarians by including Zuko as an official love interest for Katara; they even went so far as to create a maze of words to lead Katara to where Zuko stood - to make fans "prove that they'll end up together". (Here's
some of the images) But anyway, Zutara fans have been getting a bad rap for this - for "making up rumours". But they
did see that "love interest" thing appear somewhere. I, for one, can remember where it originated, though finding evidence of it will be near-impossible after so much time has passed.