How to Betray a Dragon's Hero is the eleventh book in the How To Train Your Dragon book series. It was first released on September 26, 2013.
The book starts off with Hiccup, Camicazi, Fishlegs and their dragons flying to the aid of a human calling for help. When they get there, they realize the calling came from Snotlout. The others want to leave him for fear of being betrayed (again), but Hiccup believes differently and they rescue him. In the process, they wake up the nearby Dragon Rebellion, with the help of a happy little Hogfly. During the resulting battle with the Dragon Rebellion, Camicazi is kidnapped by one of thee witches Vampire Spydragons, and Hiccup is bitten by another one.
When they reach their underground hideout, Snotlout tells them he ran away from the Alvinsmen to help them. He also tells them he can get them into the Alvinsmen's hidden war bunker. The others are still not convinced by Snotlout's excuses and ask him where his Dragonmark is. Snotlout defensively tells them he didn't take it, because it would be suspicious if one of the Alvinsmen had the Dragonmark
The Wodensfang, in response to Snotlout's reluctance to get the Dragonmark, tells the tale of Grimbeard the Ghastly (or Speedfast, as he was known as a boy) and how he was too arrogant and foolish to be a good king, how he enslaved the dragons and humans and turned the Dragonmark to the Slavemark. Snotlout shows no sign of changing his mind about the Dragonmark, and the others sleep after the story, delaying their search for Camicazi because the Dragon Furious still search for them outside the hideout.
Later that night, during what Toothless perceives to be a dream, he overhears the Dragon Furious and the Wodensfang talking. The Dragon Furious reminds the Wodensfang how harmful Hiccup and the Dragon Jewel can be. The Wodensfang makes a promise to betray the next king of the Wilderwest, if the Dragon Furious stops the rebellion till the King is crowned, on Doomsday Eve. The conversation also reveals the Wodensfang is a Seadragonus Giganticus Maximus, and Toothless is as well.
The next morning, Toothless wakes up with no recollection of his scary dream, and Snotlout leads the group to Alvin's bunker, behind the waterfall. At that moment, when only Snotlout and Hiccup entered the cave, Snotlout fetches some of the Alvinsmen and he is revealed to be a traitor. Hiccup runs back to his friends and tells them to use Plan B, which they created on the slight chance Snotlout betrayed them. Hiccup is captured and brought to the Excellinor the Witch, who delightfully takes the Last Lost Thing, Toothless, away from Hiccup, then demands he tell the witch where the Dragonmarker base is. Hiccup refuses, and the witch has Hiccup lowered into the frigid cold ocean. She brings him up, but still Hiccup refuses to give up the location, inspiring the captured Dragonmarkers and giving them hope. At last, the witch lowers him in for a final, elongated time, and Hiccup would've died from cold or just drowning, if not for the help from his Windwalker. Thanks to Hiccup's well thought out plan, though, he creates a diversion and escapes, with the help of Fishlegs and his dragons. Hiccup even rescues Camicazi, and they are all set to go back to their hideout.
But Hiccup is a Hero, of course, so he has Fishlegs and Camicazi create a diversion while he goes and tries to rescue the things. Hiccup runs into Valhallarama, his mother, but she is well disguised and Hiccup doesn't recognize her. He reaches the boat with all the Things (including Toothless, thank Thor) and tries to sail away. However, the Vampire Spydragon that bit Hiccup earlier now tracks him down because of the tooth embedded in Hiccup's arm, and he latches onto Hiccup's arm again, this time biting far deeper and worsening his already bad injury. With the help of his Windwalker, though, Hiccup throws the Vampire Spydragon off, only to have a confrontation with Snotlout.
Everyone Snotlout knew or respected Turned Their Back on him, which means he lost all his honor. He forced Hiccup to a duel with him, all the while raging and ranting about how Hiccup ruined his whole life, just by being born. Snotlout quickly beats Hiccup, but Hiccup talks Snotlout out of his raging and ranting. Snotlout agrees to help Hiccup, and Hiccup is one hundred percent sure that, this time, Snotlout will not betray him again.
Hiccup, as it turns out, was right. Snotlout and Hiccup together set sail for Tomorrow, with all the Things and it seems as though everything is going well. However, the two boys are soon set upon by a large number of the witch's dragons. They try to escape into the Winter Winds of Woden, but they are too slow, and soon there is no way for either of them to escape. Snotlout comes up with a plan, a dangerous and rash plan, but the only one that might work. Snotlout puts on Hiccup's clothes to look more like Hiccup, and he flies out on the Windwalker and distracts the Alvinsmen and the dragons. For a while, it works, and Hiccup gets far enough away for Snotlout to turn around, to get back to the ship. One of the Alvinsmen, though, gets lucky with his bow and shoots at Snotlout with a Fire Arrow, striking him in the chest and sending him falling into the ocean.
The witch and Alvinsmen are delighted with their success, almost forgetting about Hiccup's ship and the things. However, they soon remember it, and they send out dragons to get the things. Hiccup prays for him to reach the Winds, but before the boat reaches it, it's torn in half and all the Things sink down into the bottom of the ocean, and Hiccup is dragged into the Winds, along with the Wodensfang.
The Alvinsmen collect the King's Things, and they take it to Tomorrow, getting past the Druid Guardian despite Stoick the Vast's efforts to stop him. The Druid agrees to crown Alvin, and Stoick and the Dragonmarkers agree not to battle with the Alvinsmen, or outwardly oppose then. The Druid Guardian closes the island from outside forces, and leads the Dragonmarkers and Alvinsmen both into the realm of Tomorrow.
Hiccup washes up on shore soon afterward, but is still too late? Now, he has only 24 hours until Alvin is crowned King of the Wilderwest and uses the Dragon Jewel to destroy all dragons.
- Hiccup Horrendous Haddock III
- Stoick the Vast
- Excellinor the Witch
- Alvin the Treacherous
- Snotface Snotlout
- Old Wrinkly
- Humongously Hotshot the Hero
- Tantrum O'Ugerly Hotshot
- Hiccup's Windwalker
- Deadly Shadow
- The Hogfly
- Vampire Spydragons
- The Wodensfang and the Dragon Furious both speak Norse, likewise both of their Dragon Brothers (Hiccup I and Hiccup the Second respectively) could speak Dragonese.
- After Hiccup the I's father, all kings and their warriors had the Dragonmark, but Grimbeard the Ghastly turned it into the Slavemark.
- Grimbeard the Ghastly was once known as Speedfast.
- The first dragon mark was made from Hiccup I and the Wodensfang's blood
- Toothless and the Wodensfang are both Seadragonus Giganticus Maximus.
- A Seadragonus Giganticus Maximus starts tiny, grows enormous, then shrinks down again. The Wodensfang has become small again, but Toothless has not yet grown up, or even realized he was a Seadragon.
- Snotlout is 3 years older than Hiccup.
- All three Hiccup's had Seadragonus Giganticus Maximus for hunting dragons, that all had scars in the same place, on their chest.