I.
Once, only once, Iroh nearly calls Zuko, Lu Ten.
It is on his lips, that broken name, and Zuko sees it, can almost hear it, before a horrified expression drowns the word and Iroh says Prince Zuko.
Zuko almost wishes that Iroh had said it, had said Lu Ten because Zuko knows that at least that name was said with love.
At least that name was said with care.
Prince Zuko is a cold, impartial name that part of him hates.
(A small, little part of him that still thinks of blank-faced soldiers and Azula when she particularly feels like mocking him.)
Zuko looks away and pretends he doesn't notice the look on his Uncle's face like he's scared that his slip up will turn Zuko away.
(As though anything could turn him away from his Uncle for long.)
II.
His father calls him my son the same way that Azula says, my guard.
As though Zuko is just another tool at his disposal, waiting to be used, something that he owns.
Something that he is above.
Zuko calls him father and the name fits on his tongue like iron on a forge.
(Father, to him, never meant anything beyond a cold face and a bruised torso.)
III.
"I thought of you..."
"You don't have to say it, Uncle."
Iroh says it anyway.
Iroh says things like, keep your ears warm.
Don't forget your breath of fire.
Stay safe.
On Iroh's lips, on his Uncle's lips, Zuko can almost imagine the words I love you.
IV.
It's hard to imagine life without Uncle.
He has become horribly attached.
(That terrifies him.)
V.
When Iroh is in prison, silent and unwilling to answer Zuko, Zuko admits things softly.
"I thought this would make me happy," he says quietly, admitted with cautious glances to the door, "But being a fugitive with you was better than this."
His Uncle has his back to Zuko and when his shoulders shake, Zuko pretends that his Uncle is sad instead of angry.
"I've always wanted a father," Zuko says quietly, "But maybe an Uncle is better."
It's treason.
Poison on his lips.
He needs to get rid of it.
"But I forget," the words stumble out clumsily, but not as clumsy as he may have hoped, "You're a traitor."
Uncle is silent and Zuko is hurting.
VI.
"I'm sure that you were a great father," Zuko says as he sits down next to Iroh on the anniversary of Lu Ten's death.
Iroh smiles sadly at Zuko, "It doesn't matter if I was," he closes his eyes, "Just that he was a great son."
Zuko wonders if he can say the same.
(He thinks of locking Ozai in jail, of calling his father a criminal, and swallows down the question what kind of son am I?)
VII.
"He's like a father to you, isn't he?" Sokka asks as they watch Iroh.
"No," Zuko says. His voice is soft and coarse, "My father didn't care when he burnt half my face off. Uncle got worried about my ears getting too cold at the North Pole."
Sokka is silent for a moment, then he rests his head on Zuko's shoulder. "Your uncle is more of a father than your father ever was," he snarls. There is something in his voice akin to pity, but he is too angry for it to fully be that.
"Father is just a word," Zuko shrugs. Sokka's head jostles against his collar. "Uncle is a title that I hold with esteem."
He can hear the smile in Sokka's voice as he says, "You should tell him that."
VIII.
Zuko tells Iroh.
Iroh holds him close and cries into Zuko's chest.
When he is done crying, he calls Zuko nephew and it feels so much cleaner than Prince Zuko ever was.
"You need to get to work," Zuko says, glancing around the tea shop.
Instead, Iroh closes the shop and flashes a watery smile at Zuko. "If he's willing, I'd like to spend the day with my nephew instead."
IX.
"Would you prefer it," Zuko's fingers scrape the frame of Lu Ten's picture, "If I called you father?"
He is afraid of Iroh's answer.
He isn't sure which answer he'd prefer Iroh to give.
"You are my nephew and I am your uncle," Iroh kisses Zuko on the forhead, "Whatever makes you happy will make me happy. Father is just a title. It's what is in the heart that is important."
Zuko laughs, "Of course you would say that."
Inside his chest, something un-tenses.
X.
"What would you say," Iroh grins at Zuko, "If I said that I loved you?"
Zuko raises an eyebrow, "...as a son?"
"Just you," Iroh says it easily, as though it is a well known fact.
Zuko swallows down the lump in his throat. "Why?"
"Because I love you, of course," Iroh laughs loudly.
"Well," Zuko's heart hammers in his ears, "I suppose that I would say that I love you, too."
And he does.
Iroh is not his father.
Zuko is not his son.
That does not matter.
(It is not the title that is important. It is the heart that counts.)