I think that booze Kobayashi drank way back when "dragon Slayer" was misnamed. It ought to be named "Dragon Tamer" because Kobayashi has a way with dragons.
Then again, Fafnir has takiya, kanna has saikawa, and Quetzalcoatl has Shota, so maybe humans in this world (or maybe just in general) are good at persuading (seducing?) dragons, and due to the relative peace and order of their world, coexistence is possible there.