There could be a fanfic about their alliance. Maybe in an alternate universe where they have to team up against a common enemy. They could start off as enemies but gradually learn to respect and rely on each other.
There's also 'Azula's Redemption with Katara'. This fanfic focuses on Azula's journey towards redemption with Katara as a guiding force. It shows how Katara's compassion can have an impact on someone like Azula, and it has some really touching moments.
The plot is important too. It could be about them teaming up against a common enemy, or exploring a relationship that goes from hatred to friendship or more. For example, a plot where they have to navigate political intrigue together can be really engaging.
One common theme is rivalry - turned - friendship. Since they start as enemies, many fanfics explore how they can overcome their differences. Another theme is power dynamics. Azula is very powerful and Katara also has her own unique water - bending abilities, so how they interact in terms of power is often explored.
I really like 'Azula and Katara: A New Path'. In this fanfic, it starts with a rather hostile encounter between them. But as the story progresses, they discover that they have more in common than they thought, especially when it comes to their family issues and the pressure they've faced in their lives.
Well, you might find fanfictions where Azula's character undergoes a transformation and acquires healing bending through unexpected circumstances or as part of a character growth arc.
I'm not sure if there is a completely non - inappropriate 'azula and katara spanking fanfic' specifically. Fanfics can vary greatly in their nature. However, spanking themes can often be considered inappropriate or bordering on it, so it might be difficult to find one that is truly in the realm of acceptable without any concerning elements.
The themes usually revolve around the clash of their personalities at first. Katara is known for her compassion and Azula for her ruthlessness. So, the fanfictions often explore how these two opposing traits can co - exist or change in the face of love. Another important theme is the journey of understanding. They have to understand each other's motives and pasts. This is often intertwined with the theme of forgiveness, as they need to forgive each other for the things they've done in the past. And of course, there's the overarching theme of love itself, how it can grow in the most unexpected of places.