Zuko never ceased to be amazed by how different his daughters were. Izumi took after him with her dark hair and thin face while Kya, a copper-skinned, blue-eyed beauty, was pure Katara.
Clever, precocious, and serious, Izumi was Zuko's pride. At only four-years-old, she was already studying painting, calligraphy, poetry, history, languages, music, and dancing. All her tutors were amazed by her talent and erudition and more than a little annoyed with her constant questions. Why do turtle ducks carry their homes on their backs? Why did Avatar Kyoshi fight Chin the Conqueror? If you die in the Avatar State, does that mean the Cycle of Reincarnation is broken? Questions most adults never even considered.
"How is she going to learn anything if she doesn't ask?" Katara had said when the tutors came to her with their complaints.
When Izumi was two, she came down with a cold which turned to what Zuko and Katara thought was a fever. Her nursemaids came running to find them during a meeting with an official from Makepu Village, saying that Princess Izumi had sneezed and set the bedclothes on fire. This was when Zuko and Katara learned that their firstborn was a fire-bender.
Iroh was delighted when he learned this news. "She'll be another dragon like her Great-Uncle," he said. He sent scrolls of breathing exercises and fire-bending katas all the way from Ba Sing Se.
Izumi's two favorite things were looking at the illustrations in these scrolls while her father read aloud them to her and playing with her mother's chin dogs, Oma and Shu.

When Oma and Shu had puppies, Katara and Zuko allowed her to keep one, a female she named Ta Min, after Avatar Roku's lover and muse- while other little girls had fables and fairytales as bedtime stories, Izumi and had classic poetry.
Of course, the tutors were horrified when Izumi started asking how dogs had puppies. Zuko, on the other hand, couldn't help but laugh. 
Her younger sister, Kya, was Zuko's joy. Though only two, Kya's antics could make anyone laugh. Kya had taken to climbing onto the table during dinner parties and asking to know what was for dinner?
"Daifuku," she said. Her foot almost knocked over the bowl of pork dumpling soup in front of her. "Please be Daifuku." 

Izumi wrinkled up her face. "Get down," she said. "You're embarrassing us all."
Kya picked up a dumpling out of the soup bowl and threw it at Izumi.
Being as different as their respective elements, the two sisters were bound to have their clashes.
Zuko and Katara had recently discovered that Kya was a water-bender. While Izumi's favorite animals were the chin dogs who lived in the palace, Kya loved the turtle-ducks who inhabited the koi fish ponds in the garden.

Nothing amused Kya more than when Katara used her bending to create waves and ripples for the turtle ducks to ride. Katara would clap her hands and squeal "again, again." 
Every afternoon, if the weather was fine, Zuko would join his family for tea in the garden. Izumi would come running to Zuko to tell him something she'd learned during her lessons or show him a fire-bending kata she'd mastered.  Kya would sit at Katara's side by the pond and feed the turtle-ducks and watch Katara do her water-bending, the gold bracelets on her wrists and pins in her topknot sparkling in the sun. 

Something drew Katara's attention away from amusing Kya one afternoon. Kya pulled on the skirt of Katara's yellow dress and cried, "again, again."

She eventually gave up and toddled back the pond's bank, where she flicked her wrists in imitation of her mother.
Zuko and Katara came running when they heard Kya scream and prayed that their youngest hadn't fallen into the water. A turtle-duckling came sailing toward them on a small wake. Creating the wake was Kya.
Zuko scooped up his daughter and kissed her. "My little water-bender," he said. 
The turtle-duckling quickly became Kya's best friend, always following her and wanting to play or be fed. Katara and Zuko called the turtle-duckling "Kya's familiar," a familiar being a spirit companion that took the form of an animal.