When a rider-to-be impresses a dragon, the two link minds. They can speak to each other anywhere anytime. Generally, riders can only hear their own dragons but there are some exceptions though very few. When a dragon absolutely has to speak to a common person directly, they can make it so. Dragons can also teleport. They go between (read dragondex)for a few seconds and reappear where they want to be. They MUST imagine the place in their mind and concentrate otherwise they can get stuck in between.

for the book series readers, remember, this is before Aivas