It's been said that since the beginning of time, the blood of Agni himself had flown through the veins of those deemed worthy enough. Those granted the upmost honour of being known as his kin. Who were set to lead the moral world toward new hopes of prosperity and fortune with the ability to shape the future of Fire in their palms. They were given one task.
To lead, and lead, they did.
Both masters of the flame and royalty in their own right, it was only given that they be known as Fire Lord. As time grew old and dreary, so did their vision of the future. Once faithful servants of the citizens of fire. They soon forth, discovered its power to aid they own self-full desire.
As so forth, with each coming linage, their purity quelled, until all that was left of the tarnished cycle was a corrupted vision. Ambition or pure madness or two of the same? A new age of war had broken out, as by forcing his will upon the world, a certain ruler single-handedly drove the world into chaos.
Having realised the deceit of his creation, Agni couldn't bear the thought of destroying his once beloved creation. As so, he cursed his distrustful spawn, til one day, they would destroy themselves.
Using their own wrongful ambition against them. It would serve as the fuel in which would engulf an unrelenting flame from within. Set to burn, with a rage never before seen, a purge of the mind and heart.
Through spirits' whispers and woeful lore. The story of Agni's punishment soon spread like wildfire among the nation of fire.
Named after the architect of such destruction, those who know of its tale, call it;
'The Curse of the Sozin Bloodline'.
tbc.