The Dragon War
The most important question to ask yourself if you happen upon a dragon is whether it is a chromatic or metallic dragon. The chromatic dragons are servants of Skadi and sworn enemies of civilization itself. The metallic dragons serve Heimdall and defends the sentient races in a secret but ever active war. The Dragon War is mostly fought on remote mountains and deep in swamps and mortal accounts of it are rare.
# Dragon names and society
Male dragon names usually end with -es, and female names end with -ia. Depending on type, some dragons are solitary, others live in societies of varying order. For example, Black dragons are almost always solitary, while Silver dragons form complex societies, living almost like mortals. Some dragons even live in mixed roosts with multiple types of dragons. Dragons are deferential to age, and to the inherent ordering of their types.
Dragons of both sexes can reproduce without a mate, but the process is far slower and carries more risk. The chromatic dragons usually spawns a clutch of 3-5 eggs, but it is rare that more than two hatchlings survive infancy. The metallic dragons only spawn a single egg, which takes longer to hatch, but their hatchlings are not as helpless. If dragons of different types inter-breed they become the type of their mother.
# The Primordial Dragons
When Skadi, the goddess of Nature, saw the other gods giving the mortal races the tools and knowledge to build civilization, encroaching on her domain and ravaging her lands, she travelled to the outer planes and birthed a primordial dragon of each color, each stronger than the last. The first to be born from the goddess' womb was Ixes the Freezing, the ancient fore-bear of the white dragons who was imbued with the power of the freezing plane of Helheim. After Ixes came Regia the Devourer, whose black acid comes from the Swamps of Oblivion in the Elemental Plane of Earth. Next, Skadi joined her body with the River Styx, which flows through the nine Hells. The result was the green dragon Arcotoxes the Foul, who could make an entire city uninhabitable with a single breath. The blue dragon-mother Operia the Arcing was birthed in the great thunderstorms at the center of the Elemental Plane of Air. Finally, Skadi gave birth to Igrites the Ever-burning in the Fountains of Creation, volcanoes deep in the Elemental Plane of Fire.
Once all five primordial chromatic dragons had been spawned, she set them loose on the civilizations of the material plane. They were the mightiest force that young world had seen, and what remained of the mortal races went into hiding to avoid their air-borne foes.
# Forging an Opposition
Upon seeing the destruction wrought by the chromatic dragons, the other gods decided that they needed to be reigned in. Heimdall took it upon himself to make an equally powerful force and set out to forge the metallic dragons. He forged one great dragon each from brass, copper, bronze, silver, and gold and imbued them with the magic of the gods. When he was finished, he personally carried them down to the Material Plane and set them their task: protect civilization from the Chromatic Dragons.
The battles that followed brought further destruction to the world, but after almost a thousand years of war, all primordial dragons were defeated, at the cost of the lives of all the first metallic dragons, except for the Aurelia the Golden One, who was carried off to Valhalla and became the Prime Valkyrie. All that remained on the material plane were the children of these first dragons, who carry on the fight until this day. Sometimes the war flares up, leading to grand battles with hundreds of dragons when two roosts clash, but it is usually fought in the shadows with a great deal of subterfuge and proxy warfare.
# Conflict Flares
The last time the Dragon War flared was 800 years ago, when the Empire ruled most of the known lands. The metallics were on the back foot until they made an alliance with the Teccans, who sent many legions to aid against the chromatics. One of the final battles stood on Iacaris, where a massive roost of white dragons atop the Rhimer Peaks were defeated by the Ninth Legion, led by the Bladesinger Guards.
Since that time, the conflict has been quiet, with only scattered skirmishes whenever opposing dragons met by chance. Recently however, chromatic dragon activity has increased. If this is another flare-up in the making is hard to tell with the long-lived beasts.