How to Train Your Dragon Fanon Wiki
How to Train Your Dragon Fanon Wiki
Star, a Thunder-Fury.

Star is a Thunder-Fury, a powerful species of the genus 'Furia'.

"Agrh! Run for your lives! It's a THUNDER-FURY, for Thor's sake!" - Unknown Viking.

"I-I think they want their egg back." - Hiccup, on his only visit to Thunder-Fang Island.

It is debatable whether this Dragon should be placed in Strike, Mystery, Sharp, or Stoker Class. It would be hard to put into one single class, due to it's varied abilities and attributes. Right now it is in both Rapido and Strike Class.

A diagram of Star, detailing her various abilities and attributes.

A diagram of Star, detailing her various abilities and attributes.

(This dragon species was made by SnowFlakeDrake88)

Introduction & physical attributes

The Thunder Fury is an elusive, smaller relative of the Night Fury. It carries traits of a Night Fury, a Skrill, a RazorWhip and possibly a Woolly Howl. It has many similarities with its Fury cousin, however. When flying overhead, its silhouette is almost identical to that of a ‘regular‘ Night Fury, although up close, its hide is tougher than a Night Fury's. Its skin is spiky, scaly and ridged, more like a Sand Wraith’s, and, similar to a Woolly Howl, it has fluffy, warm fur running from around it's head to the wing-fins at the base of it's tail. (Baby Thunder-Furies look exactly like baby Night-Furies - their fur and colours have not grown in yet, so for a human it is easy to mistake them. Dragons, however, can smell the difference instantly.)

Its tail is also prehensile so the dragon can hang from the branches of a tree like a bat, and Thunder-Furies often like to sleep like this. The colouration of Thunder-Furies is primarily black, with iridescent markings on the top of the wings. Their under-wings, however, are a vibrant display of colours, and vary between individuals, meaning it would be possible to identify and discriminate easily between different Thunder-Furies, if any examples apart from Star are discovered.


Thunder-Furies are among some of the most intelligent dragons out there, and they display a wide range of behaviours.


Most types of fish, along with deer, cattle, sheep, and other large ground herbivores. Does not like eels, and will destroy them on sight, usually rather explosively. Fond of Dragon Nip. No instances of been recorded of cannabilisim, or of Thunder-Furies eating humans, although there have been several fatalities due to misunderstandings.

Hunting Methods

When fishing off a coast, Thunder-Furies will usually be flying below cloud level, sometimes swerving and swooping close to the ocean (apparently just for the fun of it). When they detect food, and pinpoint it's exact location - say, a salmon in the water - they will gain height, and then dive almost directly downwards on top of their prey. If fishing in a stream, the dragon will sometimes just fire a plasma blast at the water, stand in the downflow of the stream, and eat whatever fish comes towards them.

When hunting on land, they are after deer or elk, but will take cattle or other farm animals if avaliable. Usually they will begin by firing a blast at a herd, causing them to scatter, before swooping over them and picking their meal. Thunder-Furies are strong for their size, and can lift a full-grown elk easily. Sometimes, you will see them working in pairs to shepherd the group of prey animals over to a confined space - say backed up against a cliff or in a ravine, so one dragon can ferry food to hatchlings or other dragons while the second keeps the deer or cattle trapped. Thunder-Furies will also hunt with members of other species, and can get along quite well.


Little is known about the Thunder-Fury's breeding habits, however, the appear to mate for life, and both male and female raise the eggs and nuture the chicks. They are very protective of their young, and their family members.

Intelligence, Self-Awareness and Communication

Thunder-Furies have shown a remarkable degree of intelligence, even amongst Strike or Rapido Class Dragons. They can solve physical problems, such as a maze or a puzzle with relative ease, and are able to read both human and Dragon expressions. They are self-aware, knowing that the dragon they see in the mirror is simply a reflection of themselves, and they know that they are a self that acts on the world around them. They are capable of abstract thought and dream during sleep. They also appear to have an understanding of what a living creature consists of, (eg: When Star tries to explain 'Thump' and 'Puff' to SpineRuff - also known as pulse and breathing) and are one of the few Dragons who show empathy, being able to imagine what it would be like through another animal's eyes. Thunder-Furies, like most dragons, speak Dragonese, although to humans this sounds like articulated growling and purring.

While over long distances, roars or shrieks will be used, Thunder-Furies will usually communicate with allies through warbles, growls, chirps and body language, eg:

Wings spread out to sides, tail lashing the air, ears bent back, teeth and fangs bared, pupils are slits: I am angry, and inferior, at risk of harm.

Reared up on back legs, wings spread out, flaring underwing colours, mouth open, showing teeth and tongue, ears back: I am angry, and I am in charge / ready to fight / Warning.

Ears up, tail flicking slowly, round pupils, head cocked, paw raised: I am curious.

Ears up, tail swishing madly, tongue out, energetic movement, happy squeaks or chirps: I want to play!

Snap of jaws, quick movement of head and tail, eyes narrowed, low growl: Behave yourself.

Wings spread, mouth open, a roar, ears up, straight tail, in defensive stance: I will attack or defend if you provoke me - so don't.

Whimpering, ears back, low to the ground, wide pupils: I'm scared!

Wings and ears drooping, downturned head, low posture, whimpering or moaning: I'm sad/lonely/hurt.


{ From 'The Secret Of Thunder-Fang Island' Fanfiction}

In Viking times, before the rise of Toothless as Alpha, an island (ThunderFang) was discovered by Berk's DragonRiders which homed about five Thunder-Furies, four of which were breeding pairs, (three females, two males) although this was not known at the time - Thunder-Furies are exceptionally good at hiding. It otherwise only had SniffleHunches and one or two slow Hotburples - which was odd, because the only large prey on the island was deer and SniffleHunches are not fast enough to hunt deer. Because of an apparent absence of aggressive dragons, a Berkian outpost was set up there. It wasn't much - a watchtower, a boat, four guards, Terrormail, and a small farm with some animals. Thunder-Furies are rather territorial, have good memories, and most dislike humans. However, ThunderFang's Strike Class Dragons noted that there was a new food source avaliable. Within a week, half the livestock had mysteriously vanished during the night. The Vikings at ThunderFang outpost then kept a close watch. One watchman swore he saw a cow get grasped by something and levitate off the ground. (We now realise that once the stock was being guarded, the Furies cloaked themselves to avoid detection.) After this, reinforcements were sent from Berk in the form of the Dragon Riders. (This included the Twins, Fishlegs, Hiccup and their Dragons.)

Later, Toothless managed to find a Thunder-Fury via his echolocation, and he and Hiccup were able to follow her, although she was invisible half the time and nearly outflew them. She led them away from the nest, on a wild goose chase across the island. Eventually, the Night Fury and Hiccup pinned her into a ravine, and managed to get a closer look at this new species. Hiccup named this indivdual 'Blue Tiger' because of the stripes on her hide. However, Blue Tiger caused an avalanche with a plasma blast, and escaped. By this point, Toothless was too tired to keep up, and they had to abandon the chase.

Ruffnut and Tuffnut and their Zippleback managed to find a Thunder-Fury nest-cave. (The two breeding pairs were taking turns to babysit each other's young, while the other pair were hunting.) Ruff managed to steal a Thunder-Fury egg. Two screaming, protective Thunder-Furies drove them away, and left Tuffnut in a tree just to drive the point home. When the Twins arrived back at the outpost with the egg, they found that a TitanWing female Thunder-Fury (not the nesting mother, and not Blue Tiger) had ambushed Fishlegs, Meatlug and the other Viking guards. Somehow, the dragons in the cave had let another of their kind know about the stolen egg (we now know that Thunder-Furies can communicate with other members of their species in times of crisis via telepathy, allowing them to plan and think together even though they are not close enough to hear each other's roars.)

Meanwhile, Toothless and Hiccup accidentally bumped into Blue Tiger and her mate driving deer into a ravine. It later turned out that the Thunder-Furies were aiding the Snifflehunches in hunting. The Snifflehunches could sniff out prey that was hiding in dense forest, and drive them out towards the Thunder-Furies know, who would in turn shepherd a portion of the herd into a confined space where they could be killed by the Snifflehunches (the Thunder-Furies' wingspans were too wide to hover in the ravine) and then the dragons would take their prey and go their seperate ways. Hiccup realised that the Snifflehunches would not be able to live on ThunderFang Island without this symbiotic relationship. The Thunder-Furies might be able to survive, but they would not be able to catch enough prey to flourish. Shortly after this, Blue Tiger's mate spotted them and drove them off, causing them to fly back to the outpost, where the other Riders had been holed up. Toothless got knocked out of the sky by the Titanwing on his approach, so they joined the others inside the tower, while an angry Thunder-Fury tried to dig it's way into outpost through the roof. While the Vikings were discussing what to do, Blue Tiger and her mate joined the effort to break inside the tower. At first they tried to get in without danger to the egg, before pummeling the outpost with high-speed plasma blasts, and removing most of the wall with a Ray-Burn attack. When they were out in the open, the Twins revealed the egg that they had stolen. The three Thunder-Furies chased off the Viking guards, and drove Meatlug and Barf'n'Belch away. While Hiccup and Fishlegs tried to convince the Twins to return the egg to the Thunder-Furies, Toothless took the egg from Ruffnut's hands and offered it gently to Blue Tiger. She took it from the Night Fury, checked it and then picked up her egg in her talons and flew off with it, her mate following close behind with a sneakily stolen sheep. The Titanwing spread it's wings and screamed at them, before it, too, left the outpost, but not before grabbing a paticularly good cow.

Hiccup decided that the best course of action would be to leave the Thunder-Furies alone, despite their resemblance to Toothless. The farm animals were released as prey, ThunderFang Island was declared off-limits to all Berkians, and Hiccup wrote a warning in the Book Of Dragons, saying that Thunder-Furies were immortal, and impossible to trap or kill, so everyone would leave them alone. Despite extensive searching, ThunderFang Island was the only Thunder-Fury population the Riders ever encountered, although it is thought that more may have been hiding in the Hidden World. This was the only time when a confirmed sighting of these dragons was recorded for the next 300 years.


Cloaking, Electricity & 'Ice-Glass' spines

One reason this legendary Fury dragon is so good at hiding is because it does not need to heat up it’s reflective scales to ‘cloak’ itself- it can do so at will, vanishing from sight in a moment, going from visible to undetectable within the matter of a few seconds. Similar to a Night Fury Alpha, the Thunder-Fury also has the remarkable ability to channel electrical power from a lightning storm through its special 'ice-glass' spines and use to its own advantage, such as a delivering electric shocks or something called a 'StrikeWave', a formidable, but seriously draining form of defence. (Star lost conciousness soon after she first demonstrated it.)

The genetically altered Thunder-Fury known as ‘Black Magic’ is particularly adept at the 'StrikeWave', being able to electrocute up to eight opponents within a twenty-metre radius.

Thunder-Furies can also pass off as regular Night-Furies at a distance by 'dulling' their colouration, and flattening their fur, giving them an all-black hue, except for their eyes, which will remain a bright, glowing blue, partly due to their electrical conductivity, but mostly due to their reflective retina, which, similar to a cat's, reflects light, allowing them to see in even the darkest caves.


Similar to a pit-viper or an owl, Thunder-Furies can switch their sight to 'see' in thermal or night vision, which, when combined with their advanced echolocation, formidable hearing and good sense of smell allows it to track almost anything it wishes, even if the target has been submerged in water. Like all Furies, Thunder-Furies have excellent vision, being able to spot prey from 1000 metres up.

Other adaptions

The reason that we note RazorWhip traits is because from the first wing-fins to the tail fins at the end of the Dragon's tail, it is lined with shiny, mildly poisonous, razor-sharp, throw-able barbs that can be flung from its tail with unerring speed, accuracy and precision. Like the Night Fury, it sports the classic Fury tail-fins, and if it is damaged, or a fin is cut off, the dragon will be rendered flightless for a while - but the Thunder-Fury, unlike every other Fury species known, can regenerate a damaged or missing fin, growing it back over time a little like a gecko when it drops its tail.

Star, a Thunder-Fury.

Star, a Thunder-Fury.

Fire, Combat & Attack


Thunder-Furies have three known fire types: Plasma, Flammable Gel and Ray-Burn. The classic plasma blast, which detonates on impact, can be powerful enough to knock down a sea-stack or knock over a truck in a single blow. These can also be electrically charged to do further damage to technological targets if necessary. A Thunder-Fury's flammable 'spit' is similar to a Monstrous Nightmare's gel-fire. Thunder-Furies can also spread this gel through their skin via special glands, and can light certain parts of themselves on fire, usually the wing and tail struts, the spines, claws and sometimes the ears or head. Ray-Burn fire is apparently unique to Thunder-Furies - although Hell-Furies exhibit something similar. It looks rather like a Skrill's electrically charged blast but is more akin to a laser than a lightning bolt. A Ray-Burn attack will melt just about everything it comes into contact with, including Dragon Copper. It is the only dragon-fire on record which can damage this otherwise dragon-proof metal. However, this firing method uses up lots of gas and energy, so it seldom seen.


Thunder-Furies would normally never dream of attacking another of their kind, mostly because they are usually fairly passive, and partly because this could easily result in death for both fighters. However, in the instances that have been recorded (Star challenging Black Magic for the Alpha position and safety of her comrades), it shows that they are lethal opponents. After Star challenged Black Magic, each did an intimidation display, trying to make their opponent back down, before they attacked each other, wrestling with talons and teeth, and locking jaws. (It appears that Thunder-Furies have some kind of ettiquette for duels or challenges - not enough is known.)They can fight equally well on the ground and in the air. In airborne combat or defence, we see that a Thunder-Fury is an extremely agile opponent able to outmanouvere and take down helicopters and Deadly Nadders, and is even able to keep pace with a F-11 fighter jet.


Thunder-Furies are well equipped fighters, but they usually prefer to drive enemies away rather than kill. However, if provoked, and made angry (killing a member of their family or flock is an excellent way to do this) they will band together to completely annihilate the target from existence. Thunder-Furies, if attacking a target from the sky, will usually go with a dive-bomb, coming in steep and fast, firing off a series of rapid plasma shots on their approach. When they are at close range, they will spread their wings, pull up sharply and spray the target with burning gel. They will then reach a safe height to look at the damage, and position themselves for another attack run if the target is not as dead as they would like. Thunder-Furies can also wait for their revenge, as seen when DragonHunters were returning to their boats with the corpse of a young Thunder-Fury male, not being very observant. This is a record of the event:

"We didn't see 'em coming. We'd just winched the body onto one of the decks - a' dead Thunder-Fury was practically worth it's weight in gold, and it would fetch an 'normous price on the market, so we were pretty chuffed - and everything was fairly quiet as we prepared to spend the night off shore. Hendisson, the captain, said he'd seen a black shape in the clouds, and he reckoned that there were more of these solid-gold dragon treasures to be found. Then we heard this whistling noise, and three of the ten ships exploded into flames. We knew these dragons were dangerous - that's why we'd brought ten of our finest boats. They came out of nowhere, sending ship after ship sinking to the seabed, and then vanishing like phantoms into the smoke and darkness. They attacked from all direction, when you least expected it and they never, ever missed. It was impossible to tell how many there were as we fired arrows at anythin' that moved. I 'eard their calls as they communicated with each other, flapping over the mess, but never managed to hit one, even when I was sure I had a Thunder-Fury in my sights. One speedy shadow sprayed flaming purple gel over the sails of the ship me and the prize was on - they seemed determined to destroy every last one of our boats. Captain Hendriksson gave the order to 'Abandon ship!' once six o' them had sunk. Everyone started leapin' off the sides, as the dragons continued bombardin' the boats. Except for Hendriksson and me. I suppose it's true what they say - the captain goes down with the ship. Me? I was too scared to move, as I watched us become the last ship stil' afloat. In the light of the eerie purple fire that was spreadin' across the sails, I saw the flappin' shapes of the circling dragons, as they flew around our solitary ship. And then, one by one, they landed. There were five in total. A particularly large, old one, possibly a Titanwing, perched on the mast, apparently unbothered by the fire. Two more of the black dragons landed on the stern, growling softly in tandem when Hendriksson pulled out his crossbow. He pointed it at the fourth dragon, which had landed on the side. It was male, I noted, and had faint emerald-green patterning on it's scales. One of the pair fired, and the crossbow turned to ash and nothingness in a second. The fifth Thunder-Fury landed on the bow of the ship. This one, going by the ear nubs, was female, with blue irridescent tiger stripes, and rather young at that. The captain got down on his knees and started praying to Woden. I glanced at a spear, and then the Titan, hanging by its tail, dropped it's head down and growled in my ear. I didn't move, as I felt its breath on my shoulder. The striped female approached the corpse, with an expression I could only describe as heartbroken. She sniffed the dead Thunder-Fury, and put an ear over where it's heart was, listening intently for abou' a minute. I was surprised - was it checking for a' pulse? The female found nuffink, and while she stayed standin' up, her ears and wings flopped to the deck. The male, with the green patternin' nudged 'er side like a' fireside cat and purred gently in 'er ear. The other three made some low noises, and then the two black dragons at the bow picked up the body, and flew away, carrying it off back to the shore. The Titanwing perch'd on the mast gave a' loud roar, and then sprang off into the night. The female and the male nuzzled each other comfortingly for a moment, and then, they too, took off, following the shapes of the others. Hendriksson stopped praying, and started making the ship ready to leave as soon as possible. I started hauling up survivors over the side. We left with a verra full ship, and I watc'ed ThunderFang Island fade from sight..."


Thunder-Furies are powerful, but can be taken down with regular means, (usually nets or poisons. )The following is a list of weaknesses:

-Dragon Root

-'BewilderBeast's Gaze' Thunder-Furies can be hypnotised, although it is hard to do and they have been known to break free with the correct motivation.

-Sleeping gas

-Loss of energy/exhaustion or collapse from using Ray-Burn or StrikeWave.

-Tranquiliser darts

-The usual poisons (arsenic, cyanide, etc) although Thunder-Furies have a good resistance to these.

-Deathgripper venom

Dragon Codex(what to do if it tries to eat you)

Thunder-Fury: (poss. non-existent?)

Speed: Unknown

Size: Thought to look like a small Night Fury - but unconfirmed.

Firepower: Unknown, potentially limitless. Has several different fire types, all of which are deadly.

Attack Methods: Unknown. Lethal anyway.

Intelligence: Very clever. Bar the door against it, and you'll find it coming up through your floorboards.

Location: Only ever found on Thunder-Fang Island, which is now declared off-limits.

How Not To Get Eaten:

For Thor’s sake do not engage this dragon if you wish to live. Only one Viking has survived a Thunder-Fury encounter, (apparently they tried to raid a Thunder-Fury nest, by Woden’s beard!), and they were found halfway up a tree (although otherwise unharmed).The only thing to do is run like the blazes and hope your death will be short. The Thunder-Fury is an apparently immortal, supernatural beast which neither needs to sleep, eat or drink. Archers who have sighted the appartion say it's armoured scales are bigger than shields and are two feet thick! It wields the unholy power of Freya-knows-what. Extremely, extremely, gods-awfully dangerous. DO NOT attempt to kill on sight, because it will have already done this to you.

Terthian Dragon-Training Society's added notes: Thunder-Furies are certainly not immortal, and require water, protein, and rest in order to survive. It is thought that the reason archers said 'it's armoured scales are two feet thick' is because A: Thunder-Furies are small, agile, and hard to hit in the dark, and B: It is hard to shoot something when you are terrified and trembling with fear. Thunder-Furies are very clever, and certainly earn the title 'dangerous.' Star is thought to be an adolescent, and she is three meters from nose to tail. On speed, we are less certain - last time we tried to measure her flying speed the speedometer broke - however she is capable of breaking the sound barrier, and is fast and agile enough to outfly a modern day fighter jet.

Other Notes on Thunder-Furies:

The only known living example of a 'true' Thunder-Fury is the individual known as 'Star', who is currently owned by Lucy Itoro Marksmith, in the little town of Terthia-On-Sea

Read more about Star : Thunder-Fury

Read more about Black Magic : Thunder-Fury

Read about Rapido Class Dragons

Thunder-Furies appear In: ThunderWing: The Arrival and The Secret Of ThunderFang Island

Thanks for reading :)