There is a beam of light, bright and large and powerful. Iroh feels the hairs on his skin rise, the air around him wavers and shudders with the utter force of it. He hesitates, but Zuko's back is to him, he's too busy staring out, eyes fixed on the beam of light, muscles locked like he can't look away. Without a doubt, Zuko can feel it too.
Iroh puts a piece down to the game in front of him, not caring that it's not the most strategic move. His attention rounds over to Zuko. He waits for the reaction. He steels himself, but even after all this time, he's still not prepared to see the violent desperation in Zuko's eyes. For a split second as he whirls around to face him, there's no scowl, just wide-eyed wonder, the old Zuko breaks through for just a moment before it crashes back down, and tears away any hope that came with it. Zuko visibly slams the feeling down, buries it deep enough that Iroh worries he'll never be able to feel it again: that genuine wonder, eyes looking at the world and all its mysteries for just what it is.
"Uncle," Zuko hisses out the word, and it grates along Zuko's throat like it's the first word he's said in a week - and it might as well have been, with how the last few weeks have gone.
It's been two years.
Silence doesn't suit Zuko, and neither does rage. But he wears them both anyway.
Iroh pours himself another cup of tea like that will slow whatever will come out of Zuko's mouth, that he won't have to listen to his desperate words and feel the heated, never-ending fountain of pain that leaks out of Zuko's very skin.
Zuko points at the dwindling light, and he doesn't even realise that that kind of sense is special, that to feel the spiritual waves through the air itself is something to be valued and treasured. Worse that Iroh knows he can't even broach the topic with him without Zuko rejecting it. Agni forbid the child be good at something that isn't something that Ozai would have approved of.
"That was from was an incredibly powerful source," Zuko says, he's angry now, wearing it across his shoulders so tightly, Iroh worries he'll never be able to strip himself of it.
"Perhaps it was a celestial light," he says. He places another tile down and knows that Zuko won't buy his lie. He looks up, takes in the new agitation, the distant panic that's steadily burning through Zuko's reserves like a wildfire and takes a gamble. "Sit down, Prince Zuko. Have some calming tea." He regrets how it sounds immediately, patronising at best, and Zuko reacts much like he used too before they broached the iciness of the South Pole.
"I don't need calming tea, I need to capture the Avatar," his voice bounces off the icebergs. Zuko's hand shudders at his side, and he buries the action before Iroh - or anyone - can comment on it, barking orders at the Helmsman.
Iroh places his last tile down, and sees three swirls carved into the tile, the symbol of the Air Nomads, and he knows this is only the beginning.
The heat radiating from his nephew is palpable, burning through the oxygen around him like a furnace, nervous energy eating him up from the inside. It's the first sign of genuine hope that they've seen since Zuko's father sent him on this fools quest. They've personally disproven more than a dozen legends and folktales across the world, hunted down every lead right down to the nuts and bolts of it until often times all that was left was an old tale with that didn't hold more water than a sieve, started to keep curious children in their beds and curious adults away from things that shouldn't be touched. They've chased down tales of spirits and ghosts and energies and unexplainable weather events; but this is the first time that it feels like something.
It's dangerous, more than Iroh can put into words and more than Zuko can comprehend, and most certainly not enough to make him stop and consider.
Zuko stands at the rail guard of the tower, and if not for Zuko turning the air around him into a furnace, Iroh would think he was calm, with how utterly still he is.
Zuko knows he's here. He does not need to see Iroh to know this.
"You should go to bed," Iroh says, and knows his words ring hollow.
"I can't," Zuko says. His voice is less harsh than it was on the deck, but no less brutal. At least he's talking again. Iroh will take whatever Zuko throws at him, anything to replace the quiet of the last few weeks, drifting through the ice, feeling like the world was going to crush his nephew until there was nothing left of him.
"You can," he says. Silence sits between them, heavy and blistering.
"I have to find him," Zuko says. "I have to find him-" he echoes the same statement like he wants to say more, and it comes to halt at the tip of Zuko's tongue - and Iroh is faced with a familiar quandary. Push the subject, and risk Zuko reacting poorly, or let it lie, and let Zuko stew in whatever the myriad of dangerous thoughts swim around in his head. Zuko heaves a sudden breath, and it shudders through him, rattling him like a leaf in a breeze. Iroh lets it lie.
"If you must face him, it is best to do it rested," Iroh says. Zuko still won't look at him.
"I know," he says, softer. "I'll go soon."
Iroh doesn't think he will, but he can't force him to sleep, and he can't force Zuko to talk about everything that goes through his head and he can't control the damage that Ozai left his son with.
He bids Zuko goodnight, and makes his way to his rooms. He faces away from the Fire Nation insignia draped across the wall, and doesn't sleep at all.
The Avatar may give Zuko hope, but it's also the very thing that's killing him.