Kataru

Kataru is a Formling who lives in the Never-Realm, and the twin brother of Akita. He has the ability to morph between the form of a bear and a human. He is the only known Formling aside from his sister that hadn't been frozen by Boreal, who took him as a prize.

The Last of the Formlings (Flashback)
Katuru appeared in this episode in a flashback, along with Akita and the other Formlings. He gave her confidence that they will find their animal forms and will not be formless, like Vex, who had threatened the villagers. A week later, they participated in the Choosing Ceremony. During their time, the two achieved their forms with Kataru becoming a bear and his sister a wolf.

As he and Akita were celebrating in finding their animal forms, their village was frozen by the fierce Ice Dragon, Boreal on the orders of the Ice Emperor and Vex.

When Boreal attacked Akita, Kataru defends his sister. Despite warnings from his sister, Kataru stayed to fight and stood his ground. In the process, Kataru was taken prisoner by Boreal and presumed his sister died.

An Unlikely Ally
Upon seeing Lloyd leave to find Zane, Vex visits Kataru and offers him a place in the Blizzard Samurai, but being stubborn, he refused by throwing his food at Vex.

Secret of The Wolf
Kataru was disturbed by the Ice Emperor, who was banging his staff to awaken Boreal.

A Fragile Hope
When Lloyd was brought to the dungeon, Kataru greeted him. After he revealed his name, Lloyd realized he was Akita’s brother and they talked about his sister. Kataru was relieved his sister was alive, surprised that she was not frozen. Kataru then revealed he was taken as a prize by Boreal and how he lost track of time in his imprisonment. Soon, Vex arrived to taunt Lloyd about his efforts to get through to Zane and promised to destroy him. As Vex left, he taunted Kataru too by reminding him of the bars on his cell.

Kataru later advised Lloyd not to waste his strength trying to escape because it was futile. But not for long before Grimfax released and allied with them to overthrow Vex and Zane in order to free him.

Personality
Being an older brother, Kataru is shown to be kind to his sister, and would often reassure her of her doubts. He was protective of her, as he defended her when the village came under attack by the Ice Emperor. He was also relieved to hear that she was still alive after all the time he was locked up.

After finding his animal form, Kataru gained confidence and bravery as he attempted to fight back against Boreal.

During his decades of being a prisoner of the Ice Emperor, Kataru became stubborn and pessimistic, such as when he outright refused Vex's offer, and didn't believe Lloyd about Akita's survival at first.

According to Akita, he may be somewhat lazy, as he is "loud, always hungry, and sleeps half the year."

Season 11: Secrets of the Forbidden Spinjitzu

 * 116. "An Unlikely Ally" (unseen)
 * 123. "Secret of The Wolf" (unseen)
 * 124. "The Last of the Formlings" (flashback)
 * 126. "A Fragile Hope"

Trivia

 * His animal form is the bear.
 * It is confirmed that he and his sister, Akita, are twins in the official description of "The Last of the Formlings."
 * This may have been why their Choosing Ceremony was on the same day, as they are the same age.