One interesting Dark Avatar Korra fanfiction could be one where she uses her newfound 'dark' powers to fight against an ancient evil that the normal Avatar powers couldn't handle. It might show a different side of her character, more ruthless yet still with a sense of justice.
One idea could be exploring Korra's life after she restores balance. Maybe she travels the world teaching the new generation about bending. Another could be a story where she has to face a new, unknown threat that challenges her in different ways than before.
I've heard of a fanfic where Dark Avatar Korra is on a journey to restore balance in a world that has turned against the Avatar. It's a great read as it shows her using her unique powers in creative ways. The author really captures her new, edgier personality.
When writing an Avatar Korra x OC fanfic, think about the themes in the Avatar series. Things like balance, power, and identity. Incorporate these themes into your story with your OC and Korra. Give your OC some flaws, because perfect characters are boring. Have them learn and grow throughout the story. For the Korra x OC relationship, add some emotional depth. Maybe they have a shared trauma or a common goal that brings them together. And always be creative and original in your storytelling.
It could change the way benders view the Avatar's power. Seeing two Avatars from different times interact might make them realize the vast potential and flexibility of the Avatar spirit.
You can start by looking on fanfic platforms like Archive of Our Own (AO3). It has a large collection of Avatar Korra fanfics, including those with original characters (OCs). Another option is Fanfiction.net, which also has a wide variety of works. Additionally, some Tumblr blogs are dedicated to sharing and discussing Avatar Korra x OC fanfics. You might have to do a bit of searching using relevant tags like 'Avatar Korra', 'OC', and 'fanfic' on these platforms to find the ones that suit your taste.
An air - nomad who was raised outside of the traditional air - nomad culture. This character could be struggling to find their place in the world and connect with their air - nomad heritage. They meet Korra and together they explore what it means to be an air - nomad in a modern world. They could also introduce Korra to some forgotten air - nomad traditions.
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.