Headcanon Information
Toothless was born in the mountains over looking the ocean in a clutch of three. Her mother and father were killed trying to protect their nest from Vikings that came through to claim territory. Toothless was the only survivor considering that she fell out of the nest and into the water during the fray and left for dead.
Tired, cold, alone and scared, Toothless eventually came to a village and raided for food during the night since the daytime she would have been spotted and captured. Even at a young age for a dragon and no bigger than a medium sized dog, she was able to fly and hide far better than any dragon her age. Eventually, Red Death collected her into his massive swarm and forced her into service, knowing that she was one of the rarest of all the dragons.
Toothless was not only intelligent, she's very cunning and adapts well to her surroundings. She figured out very quickly that being captured meant death and being a slave was death. She needed to break free but didn't have the means to do it.
When she came to Berk to raid the village a few years later among a horde of lesser dragons, she was now grown to the point that she was deemed threatening with a breath weapon to use. The night fury was definitely formidable and highly prized by Vikings as a mark of greatness.
Scales of the Night Fury were prized as not only currency but as armor for the one that kills it. The wings were used as sails since they were strong and could tame the wind far better than canvas. The claws were used for hooks for climbing gear. To catch and kill a Night Fury and by eating its heart, according to legend, made a Viking immortal.
Toothless comes from a very noble and intelligent species of dragon that is unmatched. She'll reach maturity at 120 years of age and she's only 3. She'll reach her full height and weight by the time she's 55. Her current weight is at 190 pounds and can stand on her hind legs and walk much like a frilled lizard would. She's 10 feet tall currently from nose to butt and has a 15 foot long tail making her 25 feet total. By the time she stops growing, she'll be at 85 feet total length and weighing close to 380 pounds. Her bones are hollow but strong allowing her fast flight and her nearly flat body allows her easy maneuvering through the skies.
She's semi aquatic making her an excellent fisher. She feeds primarily off of fish and never steals from camps now that she's old enough to hunt on her own. Her eyes are made for night vision and can see long distances. Her hearing is highly acute and pick up on pitches that are inaudible to human ears. And yes, she can hear dog whistles.
Being a cross between a cat, bat and dog, she has the personality and traits of all three which includes hanging upside down, attracted to shiny things and chases anything that moves. She's loyal, affectionate and easy to train once trust is established.
Toothless can sense confrontation and tension in a given situation and will show her discomfort with grunts, growls and snarls. She can smell metal which is a strong dislike to her because of how her nest was attacked and she had never forgotten what blades did to her family. The smell of blood and battle irritates her and she shows this irritation by forcing the one that committed such acts by placing her body in a menacing way with her wings spread slightly to let the attacker know that she's not to be messed with along with a glare that chills to the bone.
She can sense a person's heart and knows through instinct who she can and cannot trust. Despite being unable to fly, she has learned that there are some things that can be done differently and running is not beyond her. She's still able to fight and can attack with great force but pinning, clawing, biting and using her breath weapon which is a combination of lightning and fire that looks like a blue and brilliant nova blast at night.