One common theme is power acquisition. For example, a character getting the power of airbending and how they learn to control it. Another is the clash of cultures. Since Naruto has its own unique ninja culture and airbending comes from the Avatar world, there can be a lot of interesting interactions between the two. And sometimes, friendship is a big theme too, like how characters from both worlds form bonds while dealing with the new concept of airbending.
Yes, there are quite a few. You can start by looking on fanfiction websites like Archive of Our Own or FanFiction.net. Just search for 'airbending naruto fanfic' and you'll find a variety of stories, some might focus on a character who can airbend in the Naruto universe, while others could be more about crossovers with the concepts of airbending from Avatar: The Last Airbender and Naruto's world.
Yes, there might be some Kai x Jinora fanfics out there. You can start by checking popular fanfic websites like Archive of Our Own. There are often many fan - created stories for different pairings in various fandoms.
I'm not sure if there is specific 'Jinora and Kai pregnant' fanfiction. You could try searching on popular fanfiction websites like Archive of Our Own or FanFiction.net.
Perhaps they are in a world where their pregnancy has some sort of special significance. Maybe it's a sign of a new era or has some magical implications. They could be on a journey to understand what this pregnancy means for themselves, their community, and the world around them. They might also have to face some antagonists who want to use the pregnancy for their own evil purposes.
It could also be a story where they are from different social groups or have some sort of obstacle in their relationship. But their love overcomes all, and the kiss is a symbol of their defiance against the odds. For instance, if Jinora is from a more respected family and Kai is an outsider, their kiss could be a statement of their love in the face of social disapproval.
Adventure themes are common too. They might go on quests together, like exploring a new, mysterious part of their world. During these adventures, they learn more about each other and their own powers. This kind of fanfiction usually has a lot of action, with Kai and Jinora using their unique abilities to face various threats and solve puzzles.
Their relationship could develop through shared experiences. For instance, if they were to take part in a training session together, they would learn more about each other's strengths and weaknesses, and grow closer as a result.
Avatar Aang was a very important figure in the Avatar universe. One appropriate story could be about Jinora learning from Aang's teachings. For example, Jinora might study the way Aang brought balance to the world and use that knowledge to help solve problems in her own time. She could be inspired by Aang's courage in facing the Fire Nation and apply that to standing up against new threats in her community.
Fanfiction.net is also a good place to look. There are many Avatar - related fanfics on this platform. Browse through the Avatar section and keep an eye out for the 'korra x jinora' ones. You might have to sift through some other stories, but it's worth it.