Maybe it's a powerful jutsu or curse that doesn't eliminate the characters outright but instead forces them to find a way to adapt and survive, leading to interesting plot twists.
The 'aang doesn't kill fanfiction' could be unique in terms of the relationships it portrays. Since Aang doesn't kill, it might show how his friends and foes react to this. Maybe some friends admire his resolve, while foes might underestimate him at first. This can lead to complex relationship dynamics that are different from the typical action - based stories where killing is more common.
It might be popular because it stays true to the essence of Aang's character. Fans who love the original show and Aang's pacifist nature would be drawn to it as it explores that side of him further.
Could be that the characters aren't relatable or the themes don't appeal to your interests. Sometimes it's just a matter of personal preference and not a reflection on the quality of the manga itself.
Well, it could be that the characters or the plot don't click with your preferences. Sometimes the art style or the way the story progresses just doesn't feel right for certain people.
Build complex characters that have depth and growth. Their decisions and reactions drive the plot forward. Also, introduce unexpected twists to keep things interesting.