Furious is the secondary antagonist of the How to Train Your Dragon book series. He is a Seadragonus Giganticus Maximus.
Furious and his brother, Hiccup Horrendous Haddock II, who got banished by his real father were adopted and raised by Grimler Dragons. When Hiccup is back to his real father, Grimbeard the Ghastly, who is the King of the Wilderwest, they spent time together. Hiccup's real brother, Thugheart, lied that Hiccup is a traitor by making humans and dragons fight. Grimbeared the Ghastly started the war against dragons and he stabbed Hiccup, and he died. As a result, Grimbeard stopped being a king because he is not worthy enough. He vanished Thugheart as an outcast and made Chucklehead, his other son, the Chief of the Hooligan Tribe.
How to Break a Dragon's Heart
Furious got captured and chained in Berserker Island and When Hiccup Horrendous Haddock III is on his hand, Hiccup recognized him and freed him, because of the scar on the dragon's chest. After he is freed, he chooses to start the war against humans.
How to Seize a Dragon's Jewel
Furious sent one of his dragon minions, the Deadly Shadow, a three-headed dragon, to find Hiccup. Once it found Hiccup, it did not attack him for recognizing the Lobster Claw Necklace.
How to Fight a Dragon's Fury
In the final battle, after Hiccup got crowned as king, Furious started fighting Hiccup when he rides his Windwalker Dragon. Furious later redeemed himself. When Excellinor the Witch is about to stab Hiccup, Furious protected him and threw the witch into the geyser and she died. Furious got stabbed and got poisoned. He went away from the Archipelago because what he did was to start the war against humans, which was very wrong.
Furious is a Seadragonus Giganticus Maximus, the biggest and most powerful dragon species. He appeared very gigantic in size. He is about twenty times bigger than the blue whale. His scales are blue and he looks like a typical dragon, but way bigger. When Furious was captured, he appeared green, because he was covered in moss.
He believes that when Hiccup III becomes king, it will be the end of the dragons, and also believes that people and dragons are mortal enemies and this is why he started the war. This is not the correct case, because when Hiccup became king, everything became peaceful.
- Hiccup I, Hiccup II, and Hiccup III owned a dragon with a scar on the chest. Hiccup I has Wodensfang, Hiccup II has Furious, and Hiccup III has Toothless.
- A Seadragonus Giganticus Maximus started as a very small baby, about a size of a nano dragon. They become gigantic after hundreds of years, then they become very small when they are old. Their lifespan is a thousand years.