Some dragons are just aggressive. No rhyme or reason to it. They like basking, eating, watching out from inside their cage, and that's about it.
I have found a couple tricks though. Dragons respond to eye contact like many other animals. Try closing your eyes and offer foods by hand. Once he begins hand feeding your at a great adcantage. Move slowly, always. Fast rapid movements seem to give dragons panic attacks. Approach him slow and low. Never over the head, and immediately give his 4 feet and tail something to stabilize on.