The theme of friendship and mentorship also pops up a lot. Even though they are from different eras, they can still form a bond. Aang can act as a mentor to Korra, guiding her through spiritual challenges that he has already faced. And Korra can show Aang how the world has changed and how she is adapting to new threats in a different time.
One great 'Aang x Korra fanfic' is 'The Avatar's Legacy'. It beautifully weaves together the different eras of Aang and Korra. The story has a great plot where they have to team up to face a new threat that combines the old and new evils in their world. The character development is on point, showing how their different personalities and experiences complement each other.
In a 'Korra meets Aang' fanfiction, a storyline could be that Korra is having trouble with her connection to the past Avatars. Aang then comes to her as a sort of mentor, guiding her through the process of strengthening that connection. They could also face a common enemy that is trying to sever the Avatar's connection to the past altogether, which would force them to fight side by side and use their combined powers and knowledge to overcome the threat.
If Korra meets Aang in fanfiction, they may have a deep conversation about the role of the Avatar. Aang could share his story of how he had to end the Hundred Years War and the toll it took on him. Korra could then talk about her struggles in the modern world with things like industrialization affecting the balance of the elements. This exchange would be really interesting as they compare and contrast their Avatar journeys.
I'm not aware of any well - written 'lemon' fanfictions for Korra and Aang as such content often goes against the family - friendly nature of the Avatar series. But if you're looking for well - written fanfictions about them in general, there are many that explore their relationship in a more appropriate way, like their roles as Avatars and how they could interact in different scenarios.
One great aang and korra fanfiction is 'The Avatar's Bond'. It beautifully explores the relationship between Aang and Korra across different timelines. They face challenges together and learn from each other's experiences as Avatars.