I was thinking a lot about this moment. Somehow it feels like the agni kai was a watershed moment not only for Zuko, but also for Iroh.
I think this something that Iroh is intensely ashamed about – and is the source of all the patience he has with Zuko and his determination to make things right for him.
Because Zuko’s scar is not just a testament of Ozai’s cruelty as a father, but is a scar on the soul of the entire Fire Nation.
Their supreme ruler publicly mutilates on his own son, a 13-year old child, who merely spoke the truth about a nation that in a quest for power has lost perspective on the worth of human life – and everyone cheers.
The scarring and humiliation of the young prince (who should be really the symbol of the future to his people) is a grotesque public spectacle.
And Iroh, who was once next in line to leading these people, former great war hero, one of the most powerful benders, and still one of the nation’s leaders – all he can do is to look away.
The boy who spoke the truth, who stood up for kindness, who tries to do the right thing, who refuses to fight his own father, who begs for forgiveness – he faces completely alone his horrible punishment, and nobody speaks up for him.
And I think this is Iroh’s moment of truth – that disagreeing privately is not enough, he cannot look away anymore. He realizes that healing this boy could be the chance to heal the Fire Nation, that he is maybe destined to be their leader, but not from the throne of the Fire Lord. He has to get Zuko through this trauma and show him kindness, love and acceptance in a way he has never experienced it. He has to teach him that speaking up and saying sorry should not and will not lead to harsh punishment, that kindness is not weakness and cruelty is not strength; that honor is not violence, but doing the right thing.
And remember how much Iroh loved his only child, his son, who was lost to the war jusy a few years before this. To see his brother Ozai treating his only son so cruely must have been horrible.
Iroh tells Zuko at the North Pole that he thinks of Zuko as his own. I think from the kindness and love Iroh showed Zuko, before the Agni Kai, it’s possible that those feelings started well before Zuko’s banishment.
@trashfolk I definitely headcanon Zuko and Iroh being close already before that. After all, he’s part of the Ember Island memories, he sends him a very nice present (that kind of also has a very personalized inscription for Zuko and that Zuko clearly cherishes). Also, Zuko goes to Iroh to get into the war council – and the manner they speak really has that element of closeness.
But I think it’s only after the banishment when they truly transform into a father/son relationship.