To clear all of the 'Book Air' theories, the creators stated that they are making a new series entirely, and on the wikipedia page it said they are calling it an 'incarnation series' Having that said made me think of going into the stories of all the past avatars. That would be interesting no?
Or I had an idea of having the avatar being the villan for once which could possibly be done.
~Kaim
This morning I had the idea that one of Aang's past lives took such thrill from having Avatar-state power that they desire to take over Aang's body and release that power onto the world. Aang would know that one of the past avatars is trying to do this but can't find out who.
It would begin when Aang goes into the Avatar State but loses control over himself, having flashbacks to the nightmares and scenes from Books 1 - 3 where he wasn't in control. aang would occasionally travel to the Spirit World to converse with a large amount of Avatars to find a likely suspect and on the way comes across some new main characters.
Of course Katara, Sokka, Toph & the gaang would appear but more focus would be made on Aang's journey. What would be interesting is if at one point during the loss of control, Aang attacks a peaceful village or a friend so the Gaang have to take Aang down themselves. Side stories could develop to ensure the other characters are still involved, such as an assassin and rebel group who still believe in Ozai's promised future and intend to kill Zuko. I think this would be interesting as it would appear a mirror to the Day of Black Sun but instead Zuko is the one being hunted down. I suppose Toph, Sokka and Katara would also be targetted by the rebel group to prevent intervention during the assassin.
Anyway, Aang would spend some time in the Spirit World but overlook a small boy/girl whose nation is unclear who is one of Aang's past lives but they were killed at a young age. Aang and this character get on well and even assists Aang finding the culprit. Aang ignores this character as a threat but it turns out this person is the Avatar trying to take over his body and regain their power. The past-life lusts for the power that was robbed from them at such a young age and it would be interesting to see a past life who is around the same age as Aang.
Although bending can not be done inside the Spirit World, physical fights clearly can still take place but with similar physiques, neither gain the upperhand. Meanwhile, in the real world, the Fire Nation Palace is attacked by rebels but the Gaang are dealing with their own attacks. Back in the Spirit World things aren't looking too good as if Aang dies in the Spirit World, his body will be left to be taken over. The battle continues into a tunnel and after a considerable amount of time, Aang defeats the past life when the Face Stealer Spirit takes the face of the past life, leaving them unable to take over Aang's body.
But it is not over yet! Aang comes back to the physical world to see the attacks all over the world but is unsure in which direction to go. He has two main choices, South Pole or Fire Palace. In the end he goes to rescue Katara who is easily holding off most of the rebels. However, in the palace, things don't look too good when Mai is attacked and left for dead in her chambers. Zuko reveals the identity of the leader to be Long Fen and the battle ensues.
Tell me, what do you think so far? Sorry it is so long.
I think that idea we had is pretty obvious.