It is one of life's most inconvenient trials that a good student does not necessarily make a good teacher. A pity, Iroh reflects, because Zuko truly is an excellent student. But…
"Again," his nephew orders. "And again and again until you get it right. What's the matter with you? Six year-olds manage to learn this set in a day!"
"Six year-old Firebenders maybe." Katara rubs a small brown hand across her forehead. "I'm not—"
"—in a position to make excuses. Unless Waterbenders are defective by nature." He eyes the girl's slumped shoulders and tired face with prominent disdain. The gesture is deliberate, though not completely fake, but it has what Iroh assumes is the desired effect; Katara's stance levels, eyes narrowing, body moving into position. The girl is not without potential. Or pride. From his angle, Iroh can see what she cannot: the approval in Zuko's eyes.
"Again. You have to be ready to--"
"Prince Zuko." Both children turn to him, unconsciously expectant. "That is enough for today. You can try again tomorrow, yes?"
"But tomorrow is—oh, fine." The boy's shoulders sag. "Fine. We'll try it again tomorrow."
Behind him, Katara's face is dejected. Perhaps this wasn't a good idea, Iroh thinks. They can instruct her about endurance, discipline, conditioning and resilience, but neither uncle nor nephew, Master nor prince, can teach Katara what she yearns to know; ultimately, they can prepare her but offer no resolution. The difference between them, Water and Fire, is simply too great to ignore. In Iroh's opinion it is a tragedy.
In Zuko's, it is a challenge.
"I don't understand why it isn't working." Glaring at the teacup in his hand, he sets it down without drinking. "You're moving correctly, most of the time, so why isn't the water responding? What's wrong with it?"
Katara refills Iroh's cup, watching the tea pour down in a graceful arc, before looking up with an exhausted expression. She picks her words slowly; he can see their careful selection happening behind her eyes.
"It feels wrong," she says finally. "Or not wrong, but not exactly right. Like trying to write with the wrong hand. Even when I manage to follow your speed, it winds up falling out of synch because following you isn't—well, I can't just follow you. It's not enough."
The lines around Zuko's mouth tighten in frustration. "It should be."
"Well, it's not." Tiredness chafes Katara's manners. "At this rate you'll be Airbending before I'll be Waterbending because–" Her expression freezes, anger suddenly overcome by a stab of inspiration. Iroh recognizes the look; it's the same one she wears moments before unscrambling a particularly intricate line of text or dissecting an especially intricate blend of tea.
"Let me borrow this," she says and snatches Zuko's still full teacup before the boy has a chance to protest. She sets the cup in the middle of the training room, the same spot they've been circling for the past three hours, and takes a long measured step back. Zuko rises to watch, coming closer.
"What are you up to?" Apparently Zuko recognizes the look too. Katara answers by pulling out the bright ribbon holding her dark braids.
"Give me your hand," she says.
Zuko doesn't move.
"Please," she says.
The prince extends his hand, rigid. The girl raises her hand to meet it. Carefully, she twines the thin length of silk around their hands, binding the two together loosely. Judging from the studious concentration on Katara's face the laxity is intentional.
"Now," she says when the last bit of ribbon is tucked into a baggy knot. "Let's go through it again."
The meaning of her idea surfaces quickly; three steps into the sequence Zuko's hand moves too fast and the tie unravels. The boy waits and watches with open displeasure as Katara redoes the binding.
"Again."
And again and again. Each time the ribbon finds a chance to slip, the sequence breaks down, and they return to the beginning. Go too fast, too aggressive, and the knot comes undone. Go too slow, too hesitant, and the sequence falls into ruin. Harmony is the goal.
Iroh watches the two with growing fascination, admiring one for his dedication, one for her ingenuity, both for their determination. Together, they push and pull, driving ambition against patience, knowledge against intuition, violence against serenity. The power of concentration wraps around them so thickly that neither child immediately notices the moment their work breeds true.
But Iroh does.
Zuko's hands are open flat, and Katara's mirror him; between them, an invisible circle is traced, its never-ending beginning bringing the pair into synchronization. The sequence is transformed into a new pattern, a compromise.
Iroh watches tea slowly spiral upward out of the cup on the floor, and he watches Fire and Water continuing to move closer, and he watches Katara and Zuko smile at each other.