Whatever a dragon actually is in that particular character's universe is the only real rule, as to what a "dragon" character is, as depictions of dragons vary a lot between character universes. Example: If dragons were purely mechanical beings in one person's universe, any dragon characters would still be considered dragons, despite also fitting into the Robot Archetype.
Common features between many dragons include:
- Reptilian nature
- Breath weapons (Usually elemental)
- Lust for gold/wealth
- Anger issues