I've been seeing a lot of "criticism" of Iroh lately that implies or outright states that Iroh failed Zuko because he didn't directly tell him that Ozai was abusive, or push harder for Zuko to see the truth. I've also been asked privately what I think of these metas, and I have to state that this seems to me to be a fundamental misunderstanding of how abuse works.
We see Zuko throughout the series deny that Ozai is abusive, believing that if he captures the Avatar, he will gain Ozai's love. This is a coping mechanism that many victims of abuse employ to deal with their situation, and it's one of the reasons it's so hard for victims to get help or leave abusive situations. Many victims do not want to see themselves as victims, and defend their abusers because they don't want to admit the pain and helplessness of the true situation.
We see Zuko be defensive of Ozai whenever Iroh gets close to telling him that he should not be trying to get back in Ozai's good graces. In season one when Zuko goes into Fire Nation waters, Iroh becomes incredibly afraid for Zuko and tells him he should not be breaking the parameters of his banishment. Zuko dismisses this and says he is sure the Firelord will understand, but Iroh says Ozai is "not the understanding type." Zuko completely ignores Iroh's words.
In other places, we see Zuko actually become hostile to Iroh when he tries to prevent Zuko from going back to Ozai. Because Zuko needs to believe that he can get back in his father's good graces, he would rather blame Iroh for trying to tell him that the relationship isn't good than admit that his father hurt him, and that it wasn't a justified punishment that he can atone for to regain his father's love and respect, it was abuse.
Iroh is put in the complicated position of trying to steer Zuko away from his abuser, but he also knows that because Zuko is hostile to attempts to get him to turn against Ozai, he risks alienating Zuko completely if he pushes him too hard, and indeed, we almost see that happen several times in the series.
We see this happen in the first episode of book two, with the introduction of Azula and her promise to take Zuko home.
Zuko: [Packing belongings.] We're going home! After three long years, it's unbelievable!
Iroh: [Staring out the window thoughtfully.] It is unbelievable. I have never known my brother to regret anything.
This time, Zuko does not ignore Iroh, but becomes hostile the more Iroh pushes him to see the truth about his father.
Zuko: Did you listen to Azula? Father's realized how important family is to him! [Irritated.] He cares about me!
Iroh: [Turns to face Zuko and holds out arms in gesture.] I care about you! And if Ozai wants you back, well, I think it may not be for the reasons you imagine.
And here we see the root of Zuko's hostility. He desperately needs to believe that his father really does care about him. Iroh, of course, is worried about Zuko getting hurt, but Zuko can't admit that his father hurt him and might do so again.
Zuko: [Turns his back to Iroh.] You don't know how my father feels about me. You don't know anything!
Iroh: Zuko, I only meant that in our family, things are not always what they seem.
Zuko: [Turns to face Iroh.] I think you are exactly what you seem! A lazy, mistrustful, shallow old man who's always been jealous of his brother!
Zuko does some typical things in this conversation that victims in abusive relationships do. One is to justify the relationship by telling the person who is on the outside that they just don't "understand" the relationship and how special it is. Zuko tells Iroh that he does not know how his father really feels about him. He also accuses Iroh of jealousy, which also feeds on the idea that Iroh just doesn't understand how special Zuko's relationship with his father is, and because Zuko knows that Iroh sees him as something of a surrogate son, he can tell himself that Iroh is just envious of Zuko and Ozai's father-son relationship.
After their fight, Zuko decides to go to Azula alone. Iroh, knowing the danger, chooses to follow him, but is immediately prepared to get Zuko out of there if he had to, and he did have to.
This is the first time Zuko chooses to leave Iroh over choosing Ozai, and it doesn't last long. The second time, though, is not too many episodes later.
In early season two, Zuko begins to use his Blue Spirit identity to steal things which he brings to Iroh, trying to gain for them some measure of what they lost. Iroh tries to tell Zuko that there is still hope, and that he doesn't need material possessions and wealth to be happy. Zuko insists that the only way he can regain his honor is to find the Avatar, and Iroh tells Zuko that he's not sure that even capturing the Avatar would fix all their problems.
This is the second time that Iroh tries to tell Zuko that following his father's orders won't fix what is wrong with their relationship. Zuko's response is to sink into a depression, then eventually decide to leave Iroh a second time.
Zuko: Uncle ... [Switch to a close-up of Iroh with Zuko on the background.] I thought a lot about what you said.
Iroh: [Iroh's sad expression clears up as he hears Zuko talk.] You did? Good, good.
Zuko: It's helped me realize something. We no longer have anything to gain by traveling together. [Iroh's brightened expression quickly disappears again.] I need to find my own way.
Rather than abandoning trying to gain his father's approval, Zuko comes to the conclusion that it's Iroh, the one who is telling him that he shouldn't be trying to seek Ozai's favor, who is holding him back and preventing him from getting it.
After Zuko leaves this time, Iroh lets him go but follows close behind, and is there to give Zuko a hand, literally and metaphorically, when he falls in "The Chase." Before that, Iroh tells Toph that he knows Zuko doesn't want him around right now, but that he'll still be there for him in the ways he can.
Iroh chooses to give Zuko space because otherwise he risks alienating him further, but provides support for Zuko when Zuko needs it. Which is sometimes the best thing you can do when someone won't leave an abusive relationship.
Zuko is not a small child that Iroh can force to stay away from Ozai, nor does Iroh want to force Zuko to do things. Zuko is a teenager and also has a degree of autonomy that real teenagers in the real world don't have. If Iroh doesn't give Zuko space, he risks pushing him more towards Ozai, and he knows it.
The one time Zuko does become harsh with Zuko is the third time Zuko leaves Iroh in book two to pursue Ozai's favor, when Iroh finds Zuko under Lake Laogai. The show itself makes the comparison to when Zuko left Iroh at the North Pole, but seeing it in relation to the times Zuko leaves Iroh in book two is an underrated aspect, I think.
At least, at the North Pole, Iroh knew that Zuko was leaving, and Zuko had promised to come back. What makes Zuko's pursuit of Appa in Ba Sing Se different is that, just like the other two times Zuko left Iroh in book two, Zuko and Iroh had had a fight beforehand about Zuko's future, where Iroh tried to push him towards abandoning his search for the Avatar, and thus, his relationship with Ozai.
When Iroh finds Zuko under Ba Sing Se, they have what is their worst fight so far. Iroh yells at Zuko and also makes it clear that he is worried about his safety, and Zuko concedes that there is no other course of action than to listen to Iroh, but he goes from snarling in anger to looking defeated as Iroh encourages him to throw away his Blue Spirit mask.
This is what leads Zuko to his spiritual sickness at the end of the episode. This is hard for Zuko because he again has to confront the reality that pursuing his relationship with his father is unhealthy, and he has to be completely dependent on Iroh. Zuko physically cannot run away this time, and thus goes through several scary experiences. If he hadn't gotten sick, though, I think it's possible that he would have tried to run away again.
The option to run back towards his father presents itself later, at the end of the season, after Zuko has already made strides towards accepting Iroh's love. In part, choosing to side with Azula and going back to the Fire Nation is Zuko giving in to those unresolved feelings for his father, and the fact that he'd been forced to rely on Iroh is part of what pushes him in the opposite direction. Being captured and forced to rely on Iroh for rescue also doesn't help that. Iroh is, of course, protecting Zuko, but Zuko processes this as feeling helpless and that leads him to feel resentment at Iroh.
Of course, it isn't Iroh who put Zuko in that position of helplessness, it was Ozai, in a broader sense, and Azula in a more immediate sense. But admitting this also means Zuko has to face the one thing he isn't ready to face, that his father's treatment of him was wrong, and that that relationship isn't worth salvaging.
On the flipside of people saying that Iroh didn't try hard enough to convince Zuko that his father was abusive, I also see people saying that Iroh pushed Zuko too hard, and I have to wonder what these people think Iroh should have done, and I don't think they understand how complex and delicate a situation like this is. As well as ignoring that a lot of what happened under Ba Sing Se was out of Iroh's control, especially considering that he was captured by the Dai Li for most of it.
