In the film
In the film, a Deadly Nadder is shown to be kept locked up for Dragon Training . Later in the movie, while battling the Red Death, Astrid Hofferson has chosen the same Deadly Nadder to ride and join the fight. At the end of the film, we see Astrid riding on the Nadder, along with the other young Vikings and their dragons.
Gift of the Night Fury
In Gift of the Night Fury, this Nadder's name is revealed to be Stormfly, and Astrid is very close to her. In the short film, Stormfly and the rest of Berk's dragons leave suddenly, and Astrid was sad that her dragon is gone.
It is revealed Stormfly and the dragons left to lay their eggs and hatch them. Stormfly herself becomes a mother of three Nadder hatchlings. Thanks to Hiccup Horrendous Haddock III and his efforts, the dragons all return to Berk, and Astrid is reunited with Stormfly and overjoyed to see Stormfly's new babies.
Legend of the Boneknapper Dragon
Stormfly makes a very short appearance in Legend of the Boneknapper Dragon. She is seen along with Astrid, dumping water over the Belch House in an effort to put out the fire, that Gobber claims to have been caused by the Boneknapper dragon.
Riders of Berk
In the TV series, Astrid still has Stormfly. Stormfly is the most beautiful dragon in the Dragon Training Academy. Astrid wakes up every morning and Stormfly is the first thing she sees. In the preview episode of the show, Astrid is heartbroken at the thought of having Stormfly being taken away, saying that she was used to having the dragon around. It should also be noted that Astrid is very excited in getting her dragon back when Hiccup announces that they can keep their dragons. In episode 3 "Animal House ", where dragons were revealed to have protective instincts, Stormfly is seen protecting sheep with her wings gently and in a comforting way at the end of the episode. Stormfly also appears to be rather intelligent, caring and protective of Astrid. The pair seem to have a strong bond, though not quite as strong as the bond between Hiccup and Toothless. In episode 7, 9 & 11, it was revealed that Stormfly will shoot her tail spines if someone touches her on her blind spot, when she is ill, or when she is startled while sleeping.
In episode 10-"Heather Report Part 1", it is shown that Stormfly is beginning to rival Toothless in speed, as Astrid was experimenting with her diet, and apparently, it was working (though Toothless may also not be as fast as he once was due to the weight of his prosthetic tail fin). Later in the same episode, it was revealed that Stormfly was able to fly faster because Astrid gives her a basketful of chicken everyday, rather than fish. She was also ridden by Heather, in episodes 10 & 11, although Hiccup noted that Heather was not capable of riding Stormfly at the same speed as Astrid could push her at. Astrid still continues to give her chicken, as it was shown in episode 13 "When Lightning Strikes". This indicates that chicken gives more stamina to a dragon, and it increases a dragon's speed, or maybe this indicates that dragons are faster and have more stamina when fed their natural diet.
In the sequel
- In the movie, Stormfly's wings are mainly yellow with some blue, but in the series they are mostly blue with some red and no yellow. This could be a mistake or it could be the fact that dragons' colors change as they age.
- Stormfly and Astrid must have some type of sync as Astrid could do handsprings and cartwheels while Stormfly flew in the air during the Thawfest Games.
- Stormfly seems to rely more on her tail spines than her fire.