Agni was cruel to all of his children.
Iroh knew that from experience, lots of experience. Agni took his wife from him, his beloved wife (Iroh refused to remarry after she died, even after he lost Lu Ten), Fearing more punishment from Agni, Iroh went to serve in the military, earning his title "the dragon of the west "
If only the people knew how broken he was inside…
He stood strong, fighting for his nation, trying to avoid another punishment sent by Agni, but all was in vein.
Agni took Lu ten from him as well
That's when Iroh lost all hope in his life, he returned to the fire nation, his nation, as a disillusioned man. Only two people accepted him back with open arms, his nephew and Ursa, his brother's wife.
Both visited him frequently, trying to sooth his pain. They took him along on their trips to the turtleduck pond, and Ursa and he watched as little Zuko got bitten by an overprotective mother turtleduck.
Their peaceful bubble was harshly bursted when Azula showed her amazing fire bending ability. When her father noticed that, he showed Zuko aside, having lost all interest in the so called "failure" of an heir. Ozai claimed Azula, and there were times when neither her brother nor her mother was allowed to visit her, afraid as Ozai was that they might ruin his precious prodigy.
Iroh knew that that wasn't the only reason why they weren't allowed to see her, he could hear her screaming on some nights, but he no longer had any power to stop this madman that he had once called his little brother.
And then Iroh's father passed away under suspicious circumstances, considering Ursa went missing on the same night. Afraid as everyone was for Ozai, no one even dared to mention the possibility that Ursa had something to do with the old Fire Lords death. So naturally, no one opposed when Ozai stole Iroh's birthright, claiming that the old Fire Lord had decided to let it be that way.
For Iroh, losing his birthright meant next to nothing. Earthly fame and power no longer meant anything to him, all he cared for at that moment was the lost young boy he had come to view as his son.
And then things got even worse. Stubborn as he was, Zuko had demanded to be let into the war chamber for a meeting with the generals. Thinking that his nephew (son as he called him in his mind) might learn anything from it (and secretly hoping that he would find out how bad war actually was) he agreed to let the young boy into the chamber.
Things went so fast…
Zuko disagreed with one of the generals and as a punishment; he had to face someone in an Agni Kai. Zuko was confident, he would surely win if he had to face the general.
No one expected that he would have to face the Fire Lord.
He couldn't do anything but watch as his nephew (son) begged for mercy and received nothing but a first full of fire.
He had only felt this guilty once before, and that was when Lu ten died. He could still remember the feeling as if it had happened yesterday, he could still remember exactly how he had felt when he realised that the boy's death, his son's death, was his fault. After all, the boy had only done what everyone had expected of him, he followed in his fathers footsteps.
Sadly, those had been far bigger than a boy his age could possibly follow, and now , he was somewhere were his father couldn't follow him.
Holding the boy that had replaced his son (even if it wasn't truly that way) he vowed never to let anything like this ever happen to this young boy again. In his mind, his decision was made, he was going to follow the boy in his banishment, even if it was the last thing he did.
It hurt Iroh so much that the boy still longed for his fathers love and acceptation, even after all that father had done to him (couldn't he see he had a father right here?) He couldn't do anything but watch as the boy struggled to follow the path his destiny had laid out for him. Even though he had known it for some time, it still hurt Iroh badly when Zuko chose Azula's lie over him.
He had humiliated himself to keep the boy fed, he had followed him to the ends of the world, had gone through tremendous rage fits fired at him by said boy, he had offered him a future that didn't need him to check behind his back everywhere he went. But most importantly, he had offered him love, something no one else (with the exception of his mother that is) had offered him.
Iroh had had a lot of time to think his life over, waiting for when the time was right to take back Ba Sing Se from the Fire Nation. But he wasn't ready when his nephew (son) entered his tent.
He chose to ignore him, perhaps he would just go away if he was ignored long enough. But instead, the boy spoke, and for the first time in years, he heard his nephew, not the arrogant prince, not the scared little boy, but his nephew, the boy he considered to be his son.
And for the first time, he felt as if the boy felt the same……Zuko finally exacted him as his father, and for the first time in years, Iroh felt real happiness