Avatar: The Legend of Korra might have cued fans in about a key curse that follows they Avatar through it's reincarnations.

leading to the creation of the Avatar state, and Wan’s ability to wield all four elements at once. Victorious over Raava and once again sealing the dark spirit in the spirit realm, Wan resolved ...

Wan had unified with Raava — an ancient spirit of peace and light ... For example, Aang had difficulty accessing the Avatar State after he was wounded by Azula's lightning when using it.

With the loss of this spirit that had all of the ... with both a spiritual version of Korra and Aang appearing within a new version of the Avatar State, and that could make for a heck of an ...

Vaatu extracted Raava (the Avatar Spirit) from Korra. Raava was attacked, causing her to disappear. By losing her, Korra ended up severing her ties with her past lives, including Aang. Although ...

the Avatar is chosen in a cyclic order of Fire, Air, Water, and Earth, where its spirit is reincarnated on whoever will be bestowed the title following the death of their predecessor. Aang of ...