Thornado

Stoick's male Thunderdrum who was introduced in the Riders of Berk episode How to Pick Your Dragon.

Forming the bond

Thornado, at first, was believed to be a "rogue dragon" that was attacking fishing boats out over the North Sea for no reason. But later on, it's revealed that he was attacking ships to fish for his wounded friend, who was unable to get food.

Thornado was captured and taken to the Academy by Stoick to train him, but Thornado was more interested in getting back to his wounded friend and left, rejecting Stoick's want to ride him. Only after Stoick protected his friend from wild boars did Thornado decided to let Stoick be his rider. And despite their newly formed bond, it's believed that Thornado and Stoick will have a 'tough love' kind of relationship.

Continuing in Dragon Flower Thornado is finally given his name because he has the power of Thor and a tornado. Also, it was apparently the only name he'd answer to.

Thornado and Stoick take their first trip when Stoick has to go to a meeting with the chief of the Shivering Shores, though Stoick is still having som trouble flying him because he claims Thornado can be "quite stubborn".
When Thornado and Stoick returned, Thornado also caught the sickness that was going around due to the blue oleander flower and immediately became weak, much to Stoick's sadness.

A soften side between the two was shown in which Stoick became very nurturing towards Thornado and he gratefully accepted the care. When Thornado was better after receiving the scauldron's venom, Stoick and Thornado had a tender gesture of touching foreheads to display affection.