Book 3, Chapter 36
Much like birds and bats, dragons have an aggressively active immune system in comparison to humans, and for much the same reasons. Simply put, for a flying animal, an inflammatory response in the face of an infection is often a death sentence, so there is significant selective pressure for immune systems which can deal with an infectious agent quickly. In the case of draconic immune systems, this goes one step further, as an unchecked infection of the dragon's hydrocarbon organ system can have literally explosive results.
As such, while there are diseases that can affect dragons—especially ones that target the dragon's symbiotic bacteria—on the whole, a typical dragon's immune system resembles a military base swarming with constant armed patrols and barriers of razor-tipped wire. A disease attempting to stage an infection of such a system needs to be extremely effective at intrusion, starting with thwarting the symbiotic bacteria in the salivary glands that are the immune system's first line of defense. These bacteria not only help dragons create the biofilm mucuses that aid with fire resistance in the otherwise vulnerable soft tissues of their mouths and throats, they are primed to help their host with fighting off any microscopic invaders who attempt to get a toehold in the tissues of the mouth and gut, as the bacteria secrete a variety of antibiotics, antivirals and antitoxins—this last being significantly important in breeds whose breath can have toxic byproducts—all of which are refined by selective pressures on the symbiotic bacteria for maximum efficaciousness.
That being said, there is still a range within the greater dragon species in terms of immunological effectiveness. If a typical dragon's immunological response is akin to a military base on high alert, then those dragons whose diets expose them to biological hazards up the ante, to being more akin to a forward artillery base with active minefields and with gunnery crews in possession of itchy trigger fingers. The saliva of many Boulder-class dragons are rich in antitoxins, including ones that can encapsulate elements such as arsenic, rendering them relatively harmless and ready for expulsion in the dragon's fecal waste (although this is not a universal defense, as the radiological poisonings from the ingestions of radioactive materials and the cancers caused by the ingestion of asbestos both demonstrate). Meanwhile, Buffalords, the premier example of a draconic immune system taken to extremes, consider botulism to be a spice in the vein of how humans consider mint or caffeine, raw pufferfish is seen as a tasty snack, and cyanide is a treat.
—An Introduction To Dragon Biology, 17th Edition, Oxford University Press, 1793
Tropes that appear in this chapter:
- Content Warnings:Chapter Trigger Warnings: Explicit Discussion of Infectious Disease, Explicit Mention of Infant Illness
- Delicate and Sickly: Valka is diagnosed with a potentially fatal illness when she's barely a few months old.
- Foregone Conclusion: With textbook sections in previous chapters detailing Valka's accomplishments in history, we know Valka will power through her illness just fine.
- Internal Reveal: Ruffnut eventually reveals the healing properties of dragons to Hiccup.
- Mythology Gag: Referencing the end of How to Train Your Dragon; during a conversation with Hiccup, Gobber admits that what Berk always needed was "A little more of this," to which Hiccup answers, "You just gestured to all of me."
- One-Steve Limit: In addition to the Kingdom of Berk, a major character, the Khagan of the Pechenegs, is also named Berk. And both have dragon armies without knowing about each other. Both think the only other major power with Dragon Riders is the Roman Byzantine Empire.
- O.O.C. Is Serious Business: When Ruffnut tells Hiccup about the healing properties of Buffalord spit, Hiccup says that he's not used to seeing her this serious. Ruffnut admits, "It's weird for me too."
- The Reveal: The Khagan's name is finally revealed in this chapter. His name is Berk Olcayto-oğlu.
- Smart People Play Chess: Invoked. Drago teaches the Kagan how to play Go, known as Hwigi at the time, because the Han considered the ancient game to be one of the four arts of gentlemanly scholars. Drago believes that if the Kagan can demonstrate that he is a good player, the Han will be more likely to accept his rule.
- Villainous Friendship: The Kagan values Drago as a friend. When most others wish to see him, it's to petition him and he has to deal with all the downsides of being a ruler. When Drago wishes to see him, it's to play a game and the Kagan gets to enjoy being a ruler.
- What the Hell, Hero?: Ruffnut delivers a variation of this to Gothi when she learns that the tribal healers have knowledge of the healing properties of the Buffalord dragon and haven't shared this knowledge with anyone out of fear of it being abused like other healing secrets, Ruffnut countering that suppressing such knowledge is just as bad as killing potential patients themselves.
