One idea could be to explore the backstories of the avatars in the brotherhood. Maybe they all come from different worlds or cultures and how they came together to form the brotherhood. Another could be a story about a new avatar joining the brotherhood and facing challenges to be accepted.
To start a brotherhood avatar fanfic, you need to do some research if there are existing canons related to it. Then, start with an interesting hook, like a mysterious event that involves the avatars. Develop your characters gradually as you write. You can also add sub - plots to make the story more engaging. For example, a love interest for one of the avatars that might conflict with their duties in the brotherhood. Write in a way that makes the reader care about the characters and their journey.
One idea could be exploring the relationship between the new characters introduced in Avatar 2 in more depth. For example, a fanfic could focus on the friendship or rivalry between two young Na'vi from different clans. Another plot could revolve around a human character who becomes stranded on Pandora and has to learn to survive with the help of the Na'vi. They could discover new areas of Pandora that were not shown in the movie, filled with unique flora and fauna. A third idea might be a fanfic that delves into the backstory of one of the main Avatar 2 characters, perhaps their family history or how they came to be in their current position.
Some might focus on the training of an Avatar's feet. Since the Avatar has to master different bending forms, their feet play a crucial role. In a fanfic, it could be about an Avatar's struggle to perfect the stances that require precise footwork in firebending, like the quick and powerful movements. Or in airbending, where the feet need to be light and flowing. This could also tie in with a mentor - apprentice relationship, where the mentor corrects the Avatar's foot positions to help them improve their bending skills.
To write a compelling character in an Avatar 2 fanfic, start with a clear backstory. For example, if it's a Na'vi character, think about their family, their clan's traditions, and how they grew up. Then, give them a unique personality trait. Maybe they are overly curious like Jake was in the first movie. Also, give them goals. It could be something as simple as wanting to be the best hunter in their clan or as complex as trying to bridge the gap between the Na'vi and humans. Physical descriptions are important too. Describe their blue skin, their long braided hair, and their big, expressive eyes.
One interesting storyline could be about a human who is stranded on Pandora and has to learn the ways of the Na'vi to survive. They form a bond with a particular Pandora creature that helps them in their journey.
There are also brotherhood fanfics in the superhero genre. Take the Batman and Robin relationship. Some fanfics delve into their brotherly connection beyond just the crime - fighting aspect, like how they support each other through personal struggles.
Growth is also a prevalent theme. As the story progresses, Piper and his brothers might grow as individuals and as a unit. They could learn new skills or gain more wisdom, all while their brotherly bond deepens and evolves.
It can divide the fandom. Some fans who are interested in the original family - friendly and positive aspects of Avatar may be put off by the existence of adult fanfic. They might feel that it's a stain on the fandom.
Avatar Yangchen fanfics can be really interesting. They often explore the character in more depth than the original source might have. Some fanfics might focus on Yangchen's early days as an Avatar, her training, and the challenges she faced. It gives readers a chance to see a different side of her, one that may not have been fully explored in the main Avatar storyline.