I've been watching Legend of Korra and I feel like there are some unanswered questions about the metallic poison that Korra was administered at the end of Season 3. While Zaheer makes it clear that the poison will draw out the Avatar State to help protect Korra, this seems to contradict everything we know about the Avatar State up to this point. It appears to imply that the Avatar State will automatically manifest itself to protect the Avatar if the Avatar is in danger. However, we know from previous episodes that:
- A fully realized Avatar has full control over entering the Avatar State.
- Korra is a fully realized Avatar, having shown the ability to control the Avatar State and connect to the Avatar's Cosmic Energy. Compare that to Aang, who spent almost the entire 3 seasons of The Last Airbender being unable to directly control the Avatar State.
- Avatar Roku was killed by a volcano, and he knew his death was imminent, but the Avatar State did not manifest uncontrollably to protect him.
- If the Avatar State always asserted itself like this, then the Avatar Cycle would end once an Avatar is killed through unnatural means (combat, poison, natural disasters, etc) which seems like a pretty terrible defense mechanism.
- Both Korra and Raava, who together define the Avatar, know that dying while in the Avatar State ends the Avatar Cycle and would presumably be inclined to preserve the Avatar Cycle over preserving Korra's life.
Considering what we know above, how is it possible for the poison to threaten Korra and draw out the Avatar State in an uncontrollable manner?