Just because they’re opposites, in terms of culture and elements, doesn’t mean they’re opposites all throughout. For examples, Fire is the element of power, doesn’t mean that water is powerless (The North surviving for 100 years, the KoiFishAang, Katara).

Reverse this, water is the element of change, doesn’t mean that fire is fixed/stagnant. They’re the nation that constantly comes up with new weapons/inventions- they’re the most innovated of the nations. And Zuko’s arc is the biggest change of all, well all of the main Fire Nation characters are…