Hideous Zippleback

The Hideous Zippleback is a large, two-headed dragon. It is sly and surprising, but certain noises can confuse it and cause it to entangle its heads.

Behavior
The dragon has two personalities and two minds, one in each head, and one often argues with the other head over what to do. This dragon reminds some Vikings of bickering siblings when they aren't running away from it. Occasionally the dragon forgets that it is a two headed dragon, and one head tries to go one way, and the other head tries to go the other way, this can be problematic.

However, its two heads also give it a deadly weapon that's unique from any other dragon species. The head on the right side breathes a green, flammable gas while the left head uses an electrical spark in its mouth to ignite the gas, creating lethal explosions. By itself, the gas can make a human disorientated if inhaled.

The Hideous Zippleback's spine has many bright red lobes that run down it. Occasionally the Zippleback will use these to hold its necks together, making it less intimidating. They have serrated fangs which they use to inject venom for predigestion. Its top teeth are much sharper and are all the same size, while its bottom teeth are very long and stick up above its jaw line.

Its two heads also can aide it in confusing its enemies. They have been known to creep up on a human and trap them between its two heads.

Appearance
In the film, the Hideous Zippleback has two long serpentine heads with two yellow eyes, two straight horns, a nose horn & a mouth of sharp fangs. The left head has longer fangs on the bottom jaw. The right head has larger teeth near the the back of the bottom jaw. The long necks have curved spikes & has a yellowish, greenish skin. It can also be other colors as well. It's body is chubby, but has two small wings for in case, flying. It's arms & legs has four sliver claws for walking or for attack. The Zippleback has two long serpentine tails for flying or for attack.

Movie
In the film, Hiccup learns from Toothless that most dragons hate eels enough to actually fear them and uses this against a Zippleback to scare it back into its den during dragon training. At the end of the movie, a Hideous Zippleback (eventually named Barf and Belch) is flown by Ruffnut and Tuffnut. Each head seems to agree with one twin.

Description
The official Website describes the Hideous Zippleback as follows: "Of all the dragons that inhabit our world, one of the most unusual and dangerous is the HIDEOUS ZIPPLEBACK. The Zippleback is one of the largest dragons you may ever encounter. It's unmistakable with its twin heads. The heads are distinct, with separate thoughts and different personalities. Like most dragons, Zipplebacks can fly, but their wings are small and they spend most of their time on the ground. Zipplebacks are solitary, preferring to hunt alone. They come out after sundown, prowling dark forests for victims. The attack of a Zippleback is like no other. Instead of breathing fire, a Zippleback makes explosions. One head BREATHES gas, and the other head LIGHTS it."

"This two-headed threat is the longest dragon and has the smallest wings & stubbiest legs.But the way it produces fire makes up for any physical drawbacks. While one head shoots out a flammable gas, the other ignites it with a spark -- allowing for attacks from long distances. “It is based more on a Siamese cat combined with a devious snakelike quality,” DeBlois says."

Trivia

 * Although the offical website states that the Hideous Zippleback is not effective in flight because of its smallHiedous_Zippleback_Concept2.jpg wings, during the young Vikings' counterattack against the Red Death in the movie, it's shown that the Zippleback (Barf and Belch) is agile, fast, and effective at flying.
 * It was believed that the Zippleback was unable to breathe gas and spark while in flight, but in the TV Series, Barf and Belch are seen to be more than capable to ignite and breathe gas without too much trouble
 * The Hideous Zippleback resembles Zmey Gorynych, the Slavic Dragon.
 * The Hideous Zippleback's two heads working together is based on the proverb, "Two heads are better than Hideous_Zippleback_Concept1.jpg".
 * It's shown in a training addition to How to Train your Dragon (film) that Hideous Zipplebacks (and other dragons) have a sense of humor; when a Hideous Zippleback attacks Ruff and Tuff while the two twins fight, the heads grin at each other as the twins continue to fight dangling from the Zippleback's mouths.
 * The Zippleback is usually greenish, but the McDonalds promo toy is blue.
 * The dragon stats say that the Zippleback is nonvenomous, but Fishlegs says it is.
 * The Zippleback's name is possibly derived from Zippo, a brand of lighter, which is fitting as one of the dragon's heads serves to light the gas produced by the other head. It could also be from zipper, as the dragon can link and unlink the spines on its neck and tail together.
 * To train a Zippleback, you must feed both heads at once, then play with the dragon.
 * Although this behavior was only seen once, when Barf and Belch approached Hiccup in the How to Train Your Dragon Movie, they fanned out their wings, flapping them slightly and started aggressively hissing at him, which mimics the behavior of the Dilophosaurus in Jurassic Park when it fans out it's frill and growls to spit venom. This behavior is presumably done to make the Zippleback seem more menacing and larger than they appear. This display is never seen again.
 * Zipplebacks only need one rider in Wildskies, How To Train Your Dragon video game and School of Dragons.
 * In battles, Zipplebacks have the secret ouroboros-like power to bite their own tails and set themselves on fire, taking on the form of a flaming wheel that knocks down their opponents like ten-pins, though this ability has not yet appeared.