Preface: I am a HUGE fan of Borges. If you are not familiar with him or Tolkinian storytelling, this is not for you. I am not interested in "sticking to the show" in ways others define it. This is indeed an AU, but alternate universes exist, both in this world and the world of Avatar, between which I don't see a true separation anyway.
Lu Ten was a shehid, a martyr, someone willing to die as to show others the glory of what might be.
He was born out of Iroh's love for the world. Born out of a nameless mother he was to be The Prince That Could Be, a hero for the world to mourn over. Countless ballads have been told about his relations with Earth Kingdom women, one of which would result in the house of Bolin.
His glory was near limitless and his treason so much more painful.
On the night of his death, his declaration to defect was made loud. For the Earth Kingdom to survive it had to become evil and replace the Fire Nation as the source of villainy one day.
One day his exploits were to be made clear
But that's what he was, unclear.
His mountains were the mountains of the earth, his spirits the spirits of water, and his fire the breath of Agni himself.
No one could tell that his father was the one who ordered him to defect.
No one could know how painful he felt.
His last breath was one for the spirits, for the spirits to guide him and advance him to the stars.
He was dead.
That is the end.
He was a son willing to die for his father, for his dream, for Ba Sing Se... and for Long Feng, it's glorious secret defender. For All. His spirit will live on. Don't believe for a moment that those who have died for the sake of the Nameless One have died, they are alive but you don't feel, it.
It, the nameless energy that surrounds as all, you don't feel, you don't see, but it is always there.
Just like his avatar Mustafa of the house of Osman, Lu Ten was someone following a secret script, the blood price had to be paid for IT.
IT, being Zuko, the "Prince who was Promised"
He had to save Zuko from himself, from Ozai and from all that is bad.
With his breath he wished for Zuko to be coddled, to be banished, to come back and take his place as the Lord of Fire.
Mustafa Kemal was Mustafa Osman in another life.
Mustafa Kemal was the father of the Turk. He lived a long and fruitful life restoring the Ottoman empire to it's former glory, his life was a golden age.