|By MarrugkMargkoff||See other fanon and fan fiction works from MarrugkMargkoff.|
Lightbending was a power given by the Sun to. Lightbending is the most powerful ability that any physical being can attain, and it can never be fully mastered. Lightbending is a limitless field of progress and learning, depending on one's own mastery of it roots.
Every living thing in the Avatar world possesses the force of life, known in their world as Chi or as aura. Every person has a Chi of a different colour, a different frequency of light. A person's history and experiences colour his Chi, making every person completely unique. Spiritbending, or Energybending, was an ability learned by some to force their Chi upon another person to affect them in some way.
Kitzhao was granted the power to channel the Sun's Chi, giving him power over light. By doing this he had the capability to bring a person back to life by exactly replicating their Chi and using it to re-enlighten their being. He also had the power to create life, as he did with the dragons each time he died.
No human has ever mastered Lightbending well enough to replicate another person's Chi, so they cannot revive the dead. However, there is one instance in which this is can occur: in the case of the Avatar and his woman.
The Avatar and his future wife are always born with differing Chi. This woman has the power to use her Chi to Spiritbend the Avatar back to life when he dies in the Avatar State. When this happens they are spiritually locked from that point until the end of their next lifetime. When they are to be reincarnated they are created as one person, since they have the same Chi, the Avatar sharing the life of the woman who he would have married (Yangchen, Kyoshi, Korra, etc.). After that lifetime as the one person they are created separate again.
Koh was once a person. He became so wicked that he developed negative Chi, or Shadow Chi. He could only maintain his life by filling this void with the Chi of others, stealing their life force. He had to kill to live. This is how he became the 'Face Stealer.' Eventually he desired to steal the Sun's Chi. Doing this would have brought an end to all living things, for it is the Sun's Chi which keeps things alive. (The Sun's Chi is white, for it is an amalgamation of all the life force that has ever existed and that ever will.) When a physical being Koh was called the 'Shadow Bringer,' for he would replace a person's Chi with shadow. In the Spirit World he became the Face Stealer, for the face represented the Chi of a person in the Spirit World.
Since earth, water, fire and air are all rooted in the Sun's Chi, some were born with genetic traits or developed traits in their Chi to be able to manipulate one of those four elements. Since the source of Firebending is from the Bender's own Chi, Firebenders have the physical potential to become a Lightbender, if they can master the three-coloured roots of Lightbending and use them all simultaneously.
For the collective works of the author, go here.