Hideous Zippleback

"A Zippleback? Exotic. Two heads, twice the status."

- Hiccup

The Hideous Zippleback is a large Mystery Class (formerly Fear Class) dragon that first appeared in How to Train Your Dragon.

Official Description
"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."

- Dragonpedia

"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."

- Dean DeBlois in an interview with USA Today.

"Gas + Spark = BOOM! This tricky and evasive 2-headed Mystery Class Dragon is double trouble . . . when it isn’t bickering with itself. The Hideous Zippleback's gas-and-spark combo makes this Dragon a powerful force in battle."

- Dragons: Rise of Berk

"The Hideous Zippleback is classified as a member of the Mystery Class in the Journal of Dragons. These dragons possess a unique method of attack: one head produces a thick green gas, while the other one produces sparks to light it on fire. Any Viking facing off against a Hideous Zippleback should also make sure to not breathe in the gas: It can easily disorient you! This species of dragons can also use the gas produced by one head to obscure itself from view. This makes it easier for the Hideous Zippleback to sneak up on its opponents."

- School of Dragons Website

Development
The Zipplebacks' head, neck, and tail movements were inspired by cobras, as they were 'fluid' and 'mesmerizing', says Simon Otto. Their posture and walking structure, however, resembles that of a Komodo dragon or a horned lizard.

Original concept art, such as Two Headed by Nico Marlet, depicted the Zippleback with three heads, and a flatter, more collapsible skull. Special attention was paid to the coloring palette, in which the combinations of yellow and red, purple and orange, and teal and orange, were tested.

"The modeling and rigging teams had more than twice the fun working on the build of this dragon: imagine what they thought when they were told this design "would have two heads and two long necks that should be able to zip together," recalls Head of Rigging Jeff Light."

- The Art of How to Train Your Dragon

The Zippleback is described to have 4,769 keyable animation controls, whereas humans only had 1,100.

Egg
In promotional material for the first movie, these eggs are described as containing buoyant natural gasses that are often mistaken for air bubbles. These bubbles give the surface of the egg a bumpy look full of craters. The eggs in School of Dragons look similar to those in the promotional material too. In Dragons: Rise of Berk, the egg doesn't have any bubbles or mark of their presence whatsoever. Instead, the egg has a pattern of scales similar to the markings on the neck and back of a Zippleback. They come in a variety of colors.

Hatchling to Adult
The Hideous Zippleback is often described as one of the most unusual dragons in the world. This dragon has two long, serpentine necks with rounded spikes on it. These spikes can 'zip' together, in order to create the illusion of one neck. At the end of the necks, are two short heads. The Zippleback has a large horn on its nose, and two thinner horns on top of its head. Like most dragons, they have yellow reptile-like eyes. The teeth in their lower jaw seem to be longer than the ones in the upper jaw, sticking out. They also have two tails, which can also 'zip' together. The end of the tail posses a fin-like structure on its tails. The official website stated that thanks to its relatively short legs and wings, the Zippleback is a slow walker and flier. Despite this, Barf and Belch has been seen flying quite fast. Their legs possess short, but strong legs with four sharp claws. The Zippleback is probably one of the longest of the medium-sized dragons, if not the biggest.

According to the Dragons: Rise of Berk mobile game, Zipplebacks have only one heart and thus, it is highly likely that they have only one set of internal organs, except for the heads, necks, and tails.

In the How to Train Your Dragon Live Spectacular, a dragon puppet appears that is simply referred to as 'Nesting Dragon'. It is probably patterned after the Hideous Zippleback, and Barf and Belch in particular. It appears to be a sinuous dragon as only coils of it are seen wrapped around a mound of dragon eggs. It has at least one head (but probably more), which has a nasal crest similar to other Zippleback representatives. It also has the characteristic blunt-ended spines along the dorsum, as well as red leopard-like spots along the body over a green-colored base.

Titan Wing
Like other Titan Wing representations, the Titan Wing Hideous Zippleback is the same in appearance as a Broad Wing Zippleback, just immensely larger. An example is Sparks and Spew, who was seen in the short image story released by DreamWorks Animation called To Tame a Titan!. Titan Wing Forms, however, appear differently in the games.

According to Dragons: Rise of Berk, Titan Wing Hideous Zipplebacks are rather colorful and have many different patterns on their bodies. Its body is greyish green and their wings have three main colors: There are a large number of spikes added and their tail tip increased in size and are more of a diamond shape.
 * Blue with white spots
 * Purple
 * Dark Green

Gas and Spark
"The Hideous Zippleback's gas-and-spark combo makes this Dragon a powerful force in battle."

- Dragons: Rise of Berk

The head on the right side breathes a green, flammable gas, while the left head produces an electrical spark from its mouth to ignite the gas, creating lethal explosions, small fire bolts, or large fire 'walls' to contain their enemies. By itself, the gas can make a human disorientated if inhaled, as shown by Fishlegs. Zippleback gas can also be used to determine the location of anything that is covered by molted Changewing skin, because it will go around the solid object. This will give the appearance of an 'empty space'.

Stealth
Hideous Zipplebacks can use their gas to hide in, which makes them very stealthy. They use it to unexpectedly strike their victims. The gas acts a smokescreen, obscuring their movements.

Flaming Ouroboros Formation
The Zippleback's special ability is to release a large amount of gas and then set themselves on fire. They bite their own tails and become a flaming wheel or Ouroboros, which they can use to knock out enemies. It is likely they have to be taught how to use this ability, however.

Venom
In the first movie, Fishlegs stated the Zippleback's venom is injected for pre-digestion, which may mean that they have a weak digestive system. However, the stats in the Dragonpedia say that the Zippleback has no venom at all.

Speed and Agility
Despite the official website claiming Zipplebacks are poor fliers and walkers, Hideous Zipplebacks have shown to be quite agile and fast. This was demonstrated in the battle with the Red Death and later also multiple times in the series. Therefore, it is safe to assume that the Zippleback is actually a quite agile and flexible dragon, although nowhere being near the fastest.

Endurance and Stamina
Zippleback is able to endure the attack of a Typhoomerang and still able to get back to try to continue the battle, as they have a large amount of stamina on their side to continue long flights to catch up with other dragons.

Climber
Hideous Zipplebacks have shown to be great climbers as Barf and Belch have shown in the episode, "We Are Family, Part 1" as they are able to climb terrains very well.

Hunting
These dragons are solitary hunters that prefer to hunt as an ambush. Since these dragons have great stealth as they will use their gas to trap their prey in and able to do sneak attack. They even able to hunt well in the bushes in the forest as for ambush hunt.

Strength and Combat
Zipplebacks have proven to be very strong as they are able to tangle their necks together to carry the weight of Gronckle, Fishlegs, Tuffnut, and Ruffnut without too many difficulties. However, a single neck of a Zippleback, as shown by Barf, isn't capable to carry a very heavy rider. They even showed some of their strength to hold their ground against Toothless.

Intelligence
While growing, hatchlings are stated in Dragonpedia to have high intellect and problem-solving abilities, such as having one head watch for danger while the other watches for food, or managing to solve complex problems such as one head scaring the prey into the mouth of the other head.

Barf and Belch have proven to be very intelligent at times. They knew to use the statue of the Eruptodon on Caldera Cay to stop the flow of the lava threatening to destroy the village, as shown in the Race to the Edge episode, "Defenders of the Wing, Part 2". They also knew to use their distress call when Hiccup was in trouble as well.

Transmitting Information
They have a special ability to simultaneously transmit information to both of their brains. For example, if one head is covered up with a blindfold and food is stuck in front of the other head, both heads will start salivating at the same time, even though only one can actually see the food. With this special ability, it makes it nearly impossible to sneak up on a Zippleback. The two heads, however, still possess their individual thoughts and different personalities.

Conflict between Personalities
The dual heads can be a vulnerability, as Drago Bludvist's forces were able to incapacitate a Zippleback by shooting darts into the neck of one head, knocking both heads out. The two heads have different personalities, and if they don't work together, it can be hard for them to do anything. They even slam into objects if both heads are not paying attention when chasing prey, as shown when a wild Zippleback chased Tuffnut into a tree. However, when Barf was stung by an immature Speed Stinger, Belch was unaffected and proceeded to drag around a paralyzed Barf who constantly emitted flammable gas.

Speed
Perhaps due to their larger size and relatively short but broad wings, Zipplebacks are slower in flight than some other species.

Dousing Spark Ability
According to How to Train Your Dragon, dousing the sparking head with water can short out the fire starting ability, leaving the Zippleback unable to light up the gas from the other head.

Loud Noises
According to a short Zippleback training video from DreamWorks Animation, the Hideous Zippleback can get confused with too much racket and loud noises. The racket may also agitate the dragon.

Behavior and Personality
The dragon has two personalities and two minds, one in each head, and often different ideas, thoughts, and personalities causes the Hideous Zippleback's heads to argue with each other 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. Even baby Zipplebacks fight over which direction to go or what to do.

It has been stated by Gobber that once this dragon is saved by a Viking, they must pay their longtime debt. They are willing to do everything to show how grateful they are of their savior by giving them fish or affection. This could be another way of training a Zippleback or any other dragon species. As Barf and Belch have proven, they will even leave their old riders behind to stay with another for his entire life until they return the favor.

It's shown in a training addition to How to Train Your Dragon 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.

Training
To train a Zippleback, you must feed both heads at once, then play with the dragon to keep them occupied. Another way to train one is to save a Zippleback's life. If this is done, they will be completely loyal to the person no matter what until they can repay the favor. This can likely be used to train one as well.

In the Game, How to Train Your Dragon, feeding ham to a Zippleback will train it. No further instructions are given. According to the game, ham is a Hideous Zippleback's favorite food.

How to Train Your Dragon
The first Zippleback is seen during Hiccup's opening narration, where he describes the Zippleback and one blasts a hut. During the gang's third test, they were pitted against a Hideous Zippleback. The dragon starts the drill with a bang, releasing gas into the arena the moment the doors are loose. Amidst the fog, it slowly picks out the students. When they face the last pair, Hiccup and Fishlegs, Fishlegs pours a bucket of water on the head that gases and the Zippleback attacks Fishlegs, who makes a prompt escape. The other head emerges from the fog, and Hiccup prepares to splash the head that sparks with water, only to miss hopelessly. 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 and they have appeared in almost every other episode since then.

Gift of the Night Fury
The Zippleback was one of the species that headed to the Rookery from Berk. A baby Zippleback was seen playing with two children when the dragons returned to Berk.

Book of Dragons
The Zippleback was introduced into further detail during this short. Bork chased his trusted sheep, Willie, into a cave that was unexpectedly a Zippleback's lair. The dragon caught Bork's attention and Bork pulled out a sword trying battling both heads. The Zippleback caused an explosion and defeated Bork. You may be able to befriend a Hideous Zippleback if you feed and play with both heads at once, keeping them occupied.

Season 2
Bucket and Mulch received a blue and green Zippleback, named Whip and Lash, during their recruitment in "Team Astrid". They later then helped defend the Edge against Dagur's attack, and received the compliment from the Twins, that they were like a better-looking mirror.

Season 6
In the episode, "A Gruff Separation", Ruffnut and Tuffnut take the Thorston Induction Trials. In the final task, the Twins complete in getting a chest from a Titan Wing Zippleback's nest.

How to Train Your Dragon 2
A blue Zippleback was first seen getting its teeth cleaned at Gobber's. Later on, some were seen in Valka's Sanctuary. During the Battle of the Bewilderbeasts, captive Zipplebacks used the Flaming Wheel technique to knock out the traps and trappers.

How to Train Your Dragon
In this game, Zipplebacks can be trained by feeding it ham. There are both trained and wild Zippleback to fight throughout the game. Zipplebacks are also customizable — their head horns, wings, feet, spine protrusions, tail ends, and color can be changed.

DreamWorks Dragons: Wild Skies
Described as 'Double Trouble, Two Heads are Better than One', this dragon resides in Black Heart Bay. In this game, only one rider is required to properly control this dragon. Training this dragon unlocks the 'Double Trouble' achievement.

Dragons: Rise of Berk
The Zippleback, as well as Barf and Belch, their mate, and offspring, Exiled Hideous Zippleback and Whip and Lash became available in Rise of Berk. Their Titan form and battle form were also made available in the game.

School of Dragons
This dragon was also made playable, along with its Titan form which was adapted from the Rise of Berk version.

How to Train Your Dragon Live Spectacular
Zipplebacks are mentioned a few times in dialogue in this theatrical retelling of the first movie. There is a small part of this production that has a serpentine-appearing dragon coiled around a mound of eggs that has very similar features to Barf and Belch that may be a live-action representation of a Zippleback. This creation is only referred to as 'Nesting Dragon'.

Trivia

 * In School of Dragons, Tuffnut said that only a Zippleback can light the gas on fire and that a Nadder can't do that. But in the second film it was shown exactly the opposite — after Barf and Belch covered the traps with gas, Stormfly set it on fire.
 * In Dragons: Rise of Berk, the Hideous Zippleback breathes gas from its left head, and sparks come from its right head. In every other incarnation, gas comes from the right head, and sparks from the left head. It is possible that Zipplebacks can actually have either arrangement, as Gobber mentioned it was "tricky" to tell which head was the spark-igniting one.
 * 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 one".
 * 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.
 * 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 pans out its 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.
 * In the early concept arts, the Hideous Zippleback had a frill similar to the Dilophosaurus.
 * The film Wrath of the Titans references the Zippleback: one of the monsters Perseus fights is a two-headed Chimera, where one of its heads spits out flammable saliva and the other one ignites it with hot embers, and working together can produce bursts of flame, just like the Zippleback.
 * Zipplebacks only need one rider in Wild Skies, How to Train Your Dragon video game  and School of Dragons.
 * It was revealed in School of Dragons that Zipplebacks and Snaptrappers share a common ancestor.