One interesting story could be about the spiritual journey Aang undertakes while getting his tattoos. Maybe he has visions during the process that give him insights into his future role as the Avatar. For example, he might see flashes of the challenges he'll face in bringing balance to the world.
Well, in fanfiction, Aang's tattoos often play a big role. They can be a way to show his connection to the Air Nomad culture that was almost lost. It could also be a visual cue for his development as a more powerful and wise Avatar. Maybe in some fanfics, the way he gets his tattoos is different from the original story, which adds an interesting twist to his character arc.
Another plotline could involve an enemy trying to stop Aang from getting his tattoos. They fear that once he has them, he'll become too powerful. So, they send various obstacles in his path, like attacking the place where he's getting the tattoos or trying to corrupt the tattoo artist.
In some fanfiction, Aang's tattoos might be depicted as glowing with a special power when he reaches a new level of understanding or connection to the Avatar state.
Well, he might get a tattoo of the Rasengan on his palm. Since the Rasengan is one of his signature moves, it would be a cool and meaningful tattoo. He could also have a tattoo of his master, Jiraiya's, book mark. It would be a way to honor his mentor. Additionally, a tattoo of the chakra pathways on his body could be an interesting concept, highlighting his ninja powers.
In some fanfictions, Aang's energybending could be explored in a more character - development - centered way. For instance, after a difficult battle, Aang realizes that his energybending has a connection to his inner peace. He then goes on a journey to better understand this connection and in the process, becomes an even more powerful and wise Avatar. He might learn that by maintaining a perfect balance within himself, his energybending can reach new heights and he can use it to heal not only physical wounds but also emotional and spiritual ones of those around him.
One interesting aang hair fanfiction could be about Aang using his hair in a unique way during a battle. Maybe his long hair gets caught in the wind and he uses it as a distraction for his opponents. For example, he could swirl his hair around to create an illusion of multiple attackers, catching the enemy off - guard.
One interesting Katara and Aang fanfiction could be about their adventures after the end of the original series. Maybe they travel to new lands and discover new bending techniques together. Another could be a story that focuses on their relationship development during a time when the Fire Nation is trying to make a comeback. There are also fanfictions that might explore an alternate universe where Katara and Aang meet in different circumstances, like if Katara was from the Fire Nation and Aang was from the Water Tribe.
One interesting 'Aang puberty fanfiction' could be about Aang struggling to control his newfound strength during puberty while also dealing with his Avatar duties. For example, he might accidentally cause a stronger gust of wind due to hormonal changes affecting his bending.
One interesting fanfiction could be where Harry's tattoos have magical properties. For example, they might glow when he's near danger or change shape depending on his mood. Another could be a story where the tattoos are a form of secret code among a group he's part of, and he has to decipher them to unlock an ancient magic. There might also be a fanfic where his tattoos are a result of a powerful spell gone wrong, and he has to figure out how to reverse it while dealing with the strange looks from others.
One interesting Dark Avatar Aang fanfiction could be where he uses his newfound dark powers to challenge the traditional order of the Four Nations. Maybe he decides that the old ways are holding the world back and tries to reshape it in a more radical way.