There are two species of dragons, I know that L.J. hasn't said there are but due to my long involvment in a game that is no longer running and My Friend Andie's imagination, I believe it only makes sense. They are decended from The first rainbow and the first dark dragon, who were brothers, created by long lost magic, before time was even a thought. Both of these magic beings have left this world, but their lines live on.
Dragons in General
In the dawn of the dragons their natural shape was that of what we would call dragons today, and they can still take on that powerful form. Over time though they have evolved to become a human shape, though their coloring is different. They have normal pigmentation of skin though it tends to twinkle in the light, and their hair colors tend to range through the rainblow with other colored highlights. Being dragons though the usually adopt a more average appearance and use that as their NORMAL SHIFT. As we all know from the Nightworld Stories (witchlight) the witches put the Dragons to sleep thousands of years ago. Well they only put the Dark dragons to sleep and they missed a few on an enclave in the Caribbean. During this time the ones not sleeping continued to evolved and no longer have horns. Those that slept it turns out loose their horns as they age and grow in power. The substances lethal to dragons are obsidion and gold. As discussed in the books dragons are the forefathers of shifters and can shift into any living being. If your character is a dragon you must list his/her origional appearance and their normal shift appearance.
Rainbow Dragons
The Rainbow Dragon was the first born of the two brothers. He had Blue scales and indigo wings with a violet crest. His decendents try to stay hidden from all, as their blood can heal any wound, and as such tend to be hunted. They are sympathetic to daybreak, though if you work for anyone in the nightworld you must try to keep your true heritage from them, just in case. As the Dragons have often taken other nightworlders as lovers there tends to be more mixed blood dragons then pure. Which is helpful in hiding. Their skin sparkles blue and their eyes are rainbow flecks in their true from and when they take true dragon form they have blue scales. Their dragon fire is red and not black like the dark dragons discussed in the books.
Dark Dragons
The Dark Dragon was the second born of the brothers and was for all purposes accidently abandoned. He had sleek black scales with white wings and crest. His decendents have healing powers as well in their blood, though not as great as the rainbow dragons. They are sympathetic to the Nightworld, and are making plans to join with Hunter Redern in a New council. Dark Dragons answer to their King Blaine Moreno, who is a long time friend of Hunter and they now share blood. Dark dragons skin tends to sparkle silver, and their eyes are normal colors. Their fire is black and is more destructive then their conterparts.
Note: there are very few if any pure rainbow or pure dark dragons. Due to the witches putting most to sleep all those centuries ago those left decided to unite the species, so almost all are mixed families. While they have different leanings a dragon will not kill another unless there is no alternative.
Disclaimer:A few years back I rpged with a girl named Andie that I became friends with. She started her own game and I was on the council to help, and she is the only person I have seen try and give the dragons their own history. I have lost contact with her and all attempts to find her have failed. The different species was her idea and the history is hers, I use it because a) its the only one and b) because it is what helped me make my characters who they are in my minds eye.. To understand her vision you should check out her old site. The Forgotten Dragon Adventures. the story has long died but I still count her a friend,and teacher. To the dragon child!