[The scales come and go with his emotions; when he's really angry, or otherwise feeling strong emotions, his magic can't be held back and changes his features - and, conversely, makes them disappear when he regains control over himself.]
Not all of us want to kill every human being they see. [They're as much individuals as humans are-- not that the hunters would care, have ever cared about that. For them, all they are is prey, creatures to be slain, either for the danger, for the glory or the price of their scales.
Not that he wasn't always considered to be an oddity amongst the other dragons, too. Why would you care about the humans, they told him, why care when the only thing they want is to kill you? When they would run from you the moment they realise what you are?]