They were all drifting.
Drifting apart in a way he couldn't stop.
He was only a child but even he could see it. The rift that was growing so steadily.
It grew when father yelled at mother.
When mother hollered about how he was turning his daughter into a monster.
When father yelled back that she was making a weakling of her son.
Zuko pressed his hands to his ears, hating that he had heard his father say such things of him. Hoping that Azula would never hear what Ursa had said of her.
It grew when mother took him to the turtle duck pond.
When she very actively excluded Azula.
Azula was much meaner to him that night, pushing and shoving him and mocking him for being unable to defend himself. And it grew some more when Ursa caught her doing so and sent her off to bed with a harsh scolding.
He could see it in Azula's eyes that she blamed him.
It grew once again when Ozai took Azula off for firebending lessons.
This time the rift's growth was his doing. Perhaps in the same way Azula resented him, he resented her for being the sole attention of father. He called her a freak and a weirdo for her blue fire. Who had blue fire anyways? It was just her. She was the odd one. She was scary and mother knew it.
And further still they drifted at the dinner table.
They soon argued openly about how the children were being raised.
Zuko got to hear about how he was a disappointment and 'a priss of a boy'.
And Azula got to hear about how she was a demon child with no ability to display compassion.
Zuko got to hear about how he was useless and better off dead.
And Azula was reminded that there was something wrong with her and that she couldn't be fixed.
For it they had taken it upon themselves to fill those roles. Azula became every bit as cold and cruel as Ursa claimed. Zuko, himself made a point of shaming father at every chance he got. For it Ursa and Ozai argued more.
For it, Zuko and Azula mimicked them.
The rift was spreading fast and there was a clear divide. It was Ozai against Ursa. And then Ursa against Azula and Ozai against Zuko. And then it was Zuko against Azula.
Iroh was an outlier.
A spectator on the side, shaking his head sadly at how far the family had drifted.