One common theme is acceptance. Since the world of 'Legend of Korra' has its own social norms, the fanfics often deal with the characters struggling to have their relationship accepted by society. For example, they might face discrimination from other benders or from the general public.
The graphic novels conclude with Korra and Asami still being together. Their relationship has evolved over the course of the story. They've faced challenges together and grown closer as a result. You can see their relationship as a positive and ongoing aspect of the final part of the graphic novels.
A third option could be 'Bending Hearts'. It's a fanfic that not only has a gay relationship as its central theme but also weaves in elements of the original 'Legend of Korra' world, like the different bending arts. It shows how the relationship is affected by the world they live in and the challenges they face together.
Well, it's also about the exploration of the Legend of Korra universe in a different way. By changing Bolin's sexual orientation, it can lead to different storylines and interactions with other characters. For example, his friendships might develop into something more romantic, and we get to see how that affects the overall dynamic in the Avatar world. Also, it gives fans a chance to see Bolin in a more vulnerable and complex state, which can be really engaging as we get to know more about his inner thoughts and feelings.
There's also 'Bolin's Hidden Love'. This fanfic delves deep into Bolin's unexpressed feelings for another male character. It shows his internal struggles and how he overcomes them. The story is beautifully written, with detailed descriptions of the Legend of Korra world and Bolin's emotions. It's really a must - read for fans who like this kind of interpretation of Bolin.
The 'lemon' aspect might be a bit hard to come by in a clean way as it often involves inappropriate content. But for normal Korra and Mako fanfictions, you could also try FanFiction.net. Some stories there might show their relationship developing, their adventures together, and how they support each other, which can be really interesting to read.
Korra could meet the founders of the different bending disciplines. She could meet the first water benders and learn about the purest form of water bending. This would not only enhance her own skills but also give her a deeper connection to her water - bending heritage.
There could be a fanfiction where the kiss is a moment of impulse. Mako and Korra have been through a lot, and the emotions just build up until they can't hold it back anymore. This could then lead to a series of events where they have to deal with the consequences of this sudden display of affection, like how it affects their friendships with others in the group.