??. . . and also his country
First, imagine a loveless father who favors a sadist of a sister who tortures you with lies, on a regular basis doing things like making you believe your father is going to murder you at age 8 and taunting you about it. As you imagine you living with that imagine that at that same age you wake up one morning looking for your mother . . . but she's gone. And you never. see. your mother. again. You never even had a chance to say goodbye. This occurs on the same morbid day that your grandfather dies. But yous still have a great future ahead of you . . . right? You are destined to inherit your father's job, a big job with a lot of responsibility. You grew up counting on this. You grew up passionate about it. You grew up depending on it. It is a position that concerns your very loyalty to that which you belong and demands a tremendous responsibility. In an effort to prepare for this you study your father's job and find something morally objectionable, so you speak out. Your father . . . the closest figure in your life . . . demands you fight him. You are on the floor in tears pleading but your father only strikes you a blow, watching coldly as you scream under the torture of your pain. But your father's not done with-holding mercy. You are banished. You can never see your family again, or any friends, or your home. And it's even worse then that. In this case, imagine you have not only been banished from your home, or your city, or your state, but america. Imagine you've been shipped off to eruope, or africa, or some other alien place of alien cultures you know nothing about. You are left with a permanent scar to remind you that you cannot return to your country or family again every time you look in the mirror, reminding you your only parent hates you every time you look out the window to see nothing recognizeable you grew up with. But you are left wth a hope . . . a lingerning, foolish hope for normality . . . at the time this hope was given to you it was a wild goose chase.
Now imagine a new and paralelle scenario. Imagine you grew up as Hitler's son, or if you'd prefer, imagine you are a jew and your father is president during WWII and you are heir to the white house. Imagine WWII has been raging and your family has been battling the nazis for 100 years. Your whole life was not only counting on you continuing in the footsteps of your father, grandfather, and great grandfather, it was just a given, no-questions asked. Like the sky is blue or you're gonna grow up. Then everything changes and you are banished, not only from your family but again, from america, to some foreign land, and you will be arrested if you ever set foot in the U.S. again. You are consumed by desperation to return home . . . .would just seven episodes of character developement drive you to betray your entire country? To drive your life to the destruction you grew up burdened with the responsibility of some day leading? To join those you grew up hating, those that killed your cousin and many more of your people (even if your side "started it").
Combine the two above scenarios
Even after seven the character developement Zuko went through, if your sister came along and convinced you, someone who's only way to obtain hope was to deny the true nature of things, that if you'd just fight with her you could not only go back to america, but go back to your home, see your friends and your father again, regain your place as heir to the white house, but also regain the love of your parent. And this was a choice between, in this scenario, all that or becoming a jew-killing nazi and not only never seeing home again, but betraying your entire family,. your entire country, your parents, grandparents, and great grandparents, and betraying the very cause you grew up your father lead, the cause you believed one day you would lead? Do you really think if you went through what Zuko did, you'd be convinced that the opposing side, in this scenario, the nazis, should be the side you joined?
Such scenarios have been repeated in courts and wars throughout time. Loyalty to one's family and country can surpass everything for someone, even overriding the will to live. If your father murdered somebody, would you turn him into the police? Would general morals over-ride loyalty??? If you were born part of a war would you turn against your country, to fight against your own family, if you disagreed with their cause? Benedict Arnold had a similar situation and does anybody think he SHOULD have chosen personal beliefs over loyalty? (as far as i'm concerned, there's no right or wrong answer to this, just consider it) If you grew up as the son of Hitler raised to be his heir, would you choose the cause of foreign countries over the cause of germany, your own father, and family loyalty? Everyone all know what you'd LIKE to answer, that you WANT the answer to be yes, but regaurdless of that, WOULD you?
(BTW, side notes; hitler's family are mostly ashamed of their family name, in the civil war soldiers went on logically pointless suicide charges because it was often family marching alongside them and they could not betray them, a lot of people in the history of war and crime have chosen both loyalty and personal morals (serial killers have been defended by their mothers in court while others have been turned in by family), so for a random person it could go either way)