Sleuther

"Look at that magnificent creature, so dangerous, so deadly. I shall name him Sleuther."

- Tuffnut naming Sleuther.

Sleuther is a Triple Stryke named by Tuffnut and befriended by Toothless who appears in Stryke Out.

History
Sleuther first appeared in the episode Stryke Out, in which he was the champion of a Dragon Fighting arena owned by the Dragon Hunters. However, fans got tired of the Triple Stryke's constant quick wins and attendance began to drop. Ryker demanded that the manager find a way to make the fights entertaining again, or else.

When Hiccup and Toothless were captured in a Dragon Hunter trap and sent to the fight ring, the manager finally found a way to boost attendance, which was to have Toothless battle the Triple Stryke. After a long battle, Toothless won and was about to kill the Triple Stryke, but noticed the pain and sadness in its eyes and allowed it to live.

It then helped Toothless, the Dragon Riders, and the other captured dragons break out of the ring and escape. However, unlike the other dragons, the Triple Stryke had been in captivity for so long, that it didn't know how to be free. However, with encouragement from Toothless, it finally left the ring. Flying back towards Toothless, the Triple Stryke revealed that it wanted to go back to Dragon's Edge with the Riders. Tuffnut named the dragon Sleuther, and they all returned to Dragon's Edge.

Personality
Sleuther has been a very aggressive dragon in the dragon fighting arena. Sleuther is known to kill other dragons as Ryker said "if the Triple Stryke kills that Night Fury." In a fight with Toothless, Sleuther was spared by Toothless as he had won the fight. Sleuther learned from Toothless that dragons don't need to kill other dragons. Sleuther has gained a lot of trust for Toothless as he wanted to live in the Edge but he showed some uncertainty of leaving the Dragon Fighting Area as he lived in captivity for too long, but Toothless gave him encouragement to be free. Later, being free, Sleuther gives out enjoyment of freedom by spinning and flying openly. He then sticks out his tongue like Toothless which shows that he is playful, just like Toothless.

Trivia

 * For some reason, this dragon is referred to as "Slasher" in Rise of Berk.
 * Sleuther was released in Rise of Berk the same day the third season of Race to the Edge aired.
 * He has a personality similar to Toothless.
 * Since Toothless was the one who taught him mercy and freedom to fly, Sleuther was technically trained by the Night Fury.