Dragons were the soul protector of what we now call earth. They protected the planet from external forces and creatures that attempted to nest and destroy the planet after the food source was gone. However, the Dragons stopped that from occurring through brutal fire-spitting battles. When Humans started to occupy the planet (Earth) they deemed the Dragons to be dangerous and a threat to their way of life.
After, several decades of humans hunting the Dragons a small group of Humans formed an alliance with the few remaining Dragons to keep them alive and most importantly, safe. After a several years of protecting the Dragons, the dragons population grew but a low number of off-springs survived and the Dragons were still on the verge of extinction.
The Dragons are unique as to their innate bonding concepts of only bonding with one Human for each Dragon which means the Dragons and Humans when bonded, it is for life. A bonding concept the Dragons called their soulmate and named their Humans "Knights" If, the human is hurt the Dragon feels the pain as well as, loose some of their life-force as to keep their soulmate alive by healing their injuries. Should, their soulmate die their Dragon goes off to solitude in caverns deep inside mountains to live in solitude and die alone.
Dragons do exists today, they live off the coast of Hawaii in the deep caverns of volcanos. The volcanos are the home of the remaining Dragons that still protect the earth from external evil forces and that the lava is the Dragons internal flame. There are a few Humans that visit the Dragons to ensure their safety.