Many creatures, including wyverns and pseudodragons, have draconic blood. However, the true dragons are only those creatures falling into the two broad categories of chromatic and metallic dragons.
The chromatic dragons—black, blue, green, red, and white—represent the evil side of dragonkind. Aggressive, gluttonous, and vain, chromatic dragons are dark sages and powerful tyrants feared by all creatures—including each other. Tiamat the Dragon Queen is the chief deity of evil dragonkind.
Chromatic dragons lust after treasure, and this greed colors their every scheme and plot. They believe that the world’s wealth belongs to them by right, and a chromatic dragon seizes that wealth without regard for the humanoids and other creatures that have “stolen” it. With its piles of coins, gleaming gems, and magic items, a dragon’s hoard is the stuff of legend.
The metallic dragons—brass, bronze, copper, gold, and silver—epitomize the good side of dragonkind. Metallic dragons preserve and protect, seeing themselves as one powerful race among the many races that have a place in the world. The chief deity of the metallic dragons is Bahamut, the Platinum Dragon.
At some point in their long lives, metallic dragons gain the magical ability to assume the forms of humanoids and beasts. When a dragon learns how to disguise itself, it inevitably obeys the urge to immerse itself in other cultures for a time. Some dragons are too shy or paranoid to stray far from their lairs and their treasure hoards, but bolder dragons love to wander city streets in humanoid form, taking in the local culture and cuisine, and amusing themselves by observing how the smaller races live.