My dragons resemble the ones in Last Airbender serpentine but with 4 legs and huge wings. They can breath fire and are capable of speech. Generally they are wild and almost never seen. The older they get the more power they aquire (there is one who is a thousand years old who can change colors like a cuddle fish, and manipulate water but can't breath fire) the most common are fire breathing dragons but you have a few elemental dragons such as the one above which is a water dragon.
Roc have a bigger size than dragons are resilient against flames and can manipulate wind to incredible degrees usually (so no oxygen no fire)