She did not actively hunt for food, instead, food was delivered to her by other dragons in the nest, acting similarly to a queen bee or a cuckoo chick. She ate any dragon that did not bring sufficient food as seen when a Gronckle brought her only a single small fish coated in saliva, which offended the Red Death and subsequently led to it being devoured moments later.
True to their reputation as the "queen of the dragons", the only grown specimen seen in the franchise demonstrated a savage, menacing and controlling nature that even a Night Fury was fearful of (at this point it is unclear whether other individuals in the species share this personality). Also, according to Valka, every nest has its queens, indicating that there could be numerous Red Deaths in the world.
Hundreds of years before the events of the film, the Red Death took over Dragon Island and thus took control of the thousands of dragons nesting there. She went into the center of the island's volcano to hibernate and had her smaller dragon subordinates bring her food. This would continue for hundreds of years.
When Berkians came to Berk, the Red Death saw them as a good source of food and ordered her dragons to raid Berk constantly for food and livestock. This prompted a generations-long war between dragons and Vikings, without the Vikings truly knowing the cause. Eventually, the Berkians used a captured Toothless to lead them to the Red Death. They drove off her slaves and caused her to come out and do battle herself. She destroyed the Berkian fleet and tried to kill as many Vikings as she could before Hiccup and the Dragon Riders showed up. Astrid and the other teens distracted the Red Death long enough for Hiccup to free Toothless and rode him into battle. Hiccup and Toothless then managed to aggravate the Red Death to fly and give chase to them. They then lured her into a cloud bank where she couldn't see them and began relentlessly bombarding her wings. She then tried to fill the entire cloud bank with fire, which set Toothless's prosthetic tail fin on fire. She then dove after them and tried to light them on fire while they were falling. However, Hiccup and Toothless ignited her flames while they were still in her mouth, causing an explosion in her mouth. Upon noticing the ground rapidly approaching, the Red Death tried to slow her descent by spreading her wings, but they were rendered useless after being torn apart by Toothless' plasma blasts. She then smashed into the ground at full-speed, triggering a massive explosion. However, as her body sank into the flames, her clubbed tail knocked Hiccup into the inferno, causing him to lose his leg.
The Red Death was a gigantic, gray dragon with red spots all over her. She also was covered in coral-like spikes and frills. She had six blue eyes and a massive club on the end of her tail. She had ragged-looking (but functional) wings and huge nostrils, leading Fishlegs to believe that she relies on them more than eyesight. Like most dragon species, she had a noticeable underbite with long, jagged teeth. She had four, broad, flat feet armed with claws.
The Red Death was an ancient Titan Wing dragon, using her imposing size to terrorize other dragons into catching her prey and to destroy her enemies. However, when she felt directly threatened, she was more than willing to fight her own battles. While chasing Hiccup and Toothless through the skies, she was seen becoming increasingly agitated after being unable to catch the smaller, faster dragon and his rider. During her final moments, while plummeting to the ground, she was visibly frightened as she was unable to slow her descent.
Abilities, Talents, and Skills
Firepower: The Red Death had huge amounts of firepower, as she was able to burn an entire fleet of boats in seconds, and fill a huge cloudbank with flames in even less time. Ironically, her own firepower would lead to her downfall.
Lava-proof Skin: The Red Death was able to hibernate in lava for most of her life.
Speed and Agility: The Red Death was shown to be quite fast when she needed to be, even fast enough to keep up with Toothless, a Night Fury. However, she was not an agile dragon, as her large size led to her crashing through obstacles rather than being able to maneuver around them.
Strength: The Red Death was a very strong dragon, able to crash through sea stacks without even slowing down, and able to take the attacks of several other dragons and many Vikings, including a Night Fury, without seeming to take any damage. Her two massive, powerful wings could keep her in flight for several minutes despite her size and weight.
Mind-Control: Like a Bewilderbeast, the Red Death was able to control the minds of other dragons to serve her and be her slaves.
The Red Death perceived Hiccup and Toothless as dangerous threats and attempted to kill them every time she saw them. Eventually, Hiccup and Toothless outsmarted the Red Death by igniting the gas in her mouth, killing her.
Thousands of Enslaved Dragons
Although the Red Death was the Alpha of her flock, she did not care for the well-being of her subordinates. If any of the dragons failed to bring a sufficient amount of food, she would eat them instead. This behavior made every dragon that served her fearful of her, and they only served her because she mind-controlled them.