Thornado

Appearance
Thornado is an average-sized male brown wolf.

Personality
Thornado is playful, spirited, and slightly adventurous. As an adult, he is described to be stubborn, stuck-up and confident.

Storm
Storm became heavily protective over Thornado after her other two pups died but otherwise was just fiercely protective of Thornado. It was just a generic wolf mother-son relationship otherwise.

Citrine
Thornado often begged for Citrine's attention, but Citrine often ignored him beyond feeding him. Thornado's hopes rose every time Citrine leaned down to feed him but dropped again when Citrine immediately lost interest in his son.

Sky
Sky and Thornado argued and wrestled sometimes and weren't close, but they weren't distanced. They teased each other and if Sky had survived they would've protected each other the best they could, but Thornado wasn't as completely crushed as Breeze when Sky died.

Typhoon
Thornado would always tease Sky, Typhoon, and Breeze - Sky for her coloring, Typhoon for standing up for her, and Breeze for his small size. However, he was crushed horribly by Typhoon and Sky's deaths but felt closer to Breeze because of him being the only other one in his litter to have survived.

Breeze
Breeze and Thornado were close brothers, and even closer once they became the only remaining wolves in their litter. They playfully fought and stuck close to each other sides as best as they could.

Trivia

 * Thornado is a Thunderdrum in How to Train Your Dragon: Riders of Berk.
 * Thornado is one of the two only survivors out of Storm's two litters.