Yangchen

"air"

- Selfless duty calls you to sacrifice your own spiritual needs and do whatever it takes to protect the World.

Avatar Yangchen was the Avatar incarnate born out of the Air Nomads before Aang. Aang first sees her as a nameless Airbending avatar when Roku explains what the Avatar State is. Later she introduces herself to him when he is in a coma following Azula's lightning attack. He does not remember this encounter when he awakens from the coma. Finally, she manifests before him when he is meditating on how to stop Ozai without killing him, imparting the advice he must sacrifice his own spiritual needs if the world requires it.

Yangchen was a respected Avatar noted for her wisdom and power. Though an Air Nomad, Yangchen was feared in her time due to her willingness to do "whatever it takes" to protect the world and keep it in balance.

Background
Yangchen was born and raised in the Western Air Temple. She was so respected as an Avatar that two statues were made of her: one in the Eastern Air Temple and one in the Western Air Temple. She was so dedicated to her duty that for one whole generation after her death there were no threats of war.

Appearances during Aang's Life
Yangchen was a very wise and powerful Avatar. During her brief meeting with Aang, she convinced Aang not to feel guilty, seeing as how previous Avatars had also struggled and made mistakes. Although very little about her history is revealed, she feels very empathetic towards Aang's shame at failing to protect Ba Sing Se. This indicates that she may have made similar mistakes during her time as the Avatar.

Yangchen also imparted to Aang the purpose behind why the Avatar is born human: the Avatar must be compassionate to all people, and the only way of doing so is living among them. If the Avatar were instead an all-powerful immortal spirit living at the top of a mountain, he wouldn't have anything in common with ordinary people. She acknowledges that the Avatar must experience human life and emotions, such as sadness, anger, joy, and happiness. The Avatar must learn how precious human life is so he will see why he must do anything to protect it, and that with every incarnation, the Avatar Spirit comes closer to fully comprehending what it truly means to be human.

By the end of the meeting, Aang learns that the Avatar Spirit has been healed, although his ability to enter the Avatar State has been disrupted, so he'll now have to rely on his friends rather than his past lives. Yangchen bids him farewell, saying that his journey in the Spirit World, reconnecting with his past lives, will be like a forgotten dream.

When on the Lion Turtle, Yangchen was the last Avatar Aang thought to summon, thinking an Air Nomad Avatar would sympathize with him best. She agreed that all life is sacred, and that many great Air Nomads have achieved spiritual enlightenment using this philosophy. However, as Avatar, this is not possible since his first duty is to the world, which requires him to sacrifice his own spiritual needs. Upon hearing this advice from an Air Nomad Avatar, Aang realizes he must do whatever it takes to stop Ozai, even if it means disregarding his own non-violent philosophy and taking the Fire Lord's life.

Trivia

 * When abruptly asked for the name of the female Airbender Avatar at the Pacific Media Expo, Bryan Konietzko (jokingly) dubbed her "Avatar Susan", indicating that they initially didn't plan on developing the previous Avatars aside from the two already introduced.
 * Though there are statues of her in both the Eastern and Western Air Temples, she grew up in the Western Air Temple.