Teloch asked: Okay, new line of thought. Some alternate AU where Zuko and Azula take the place of Sokka and Katara. Either by making them water tribe or making the water tribe the villains of Last Airbender. How would this affect their relationship and the series?

Making the water tribe evil, while still having Zuko and Azula be on the evil side at the beginning, wouldn't change anything in their story besides the element they use to fight. Having them swap places with Sokka and Katara however, would make a huge difference in their lives. They'd still end up being traumatized kids, but would have had a much happier life, and an insanely healthier family. They'd actually be in good terms and I feel like that would make them realize their feelings for each other sooner, and they'd be a much more functional couple since they wouldn't have all the baggage of their past rivalry and the need to "defeat" (dominate) each other. They might become slightly more codependent though.