...and they say you're a dragon rider
and they say you skim through the clouds in a dream
of better days
and mist covering your ghosts.
... and I say you're a dragon rider
and I see you fly towards me,
golden eyes and scorching breath,
and we know the mist covers the ghosts of your past
they're left far behind in the distance...
A dragon rider is somebody who rides a dragon, and can speak to them verbally and often telepathically. Often, they can converse with any winged creature, especially birds. Dragon riders are sometimes used in fantasy novels, but they are not found in mythology.
stupot adds that: "There are dragon riders in The Lure of the Wyrm which is a story in the second discworld book, I believe. (Imaginary dragons, but they definitely ride them!)"
wertperch corrects: The dragons in The Colour of Magic (I think) were not imaginary, but magical. They were summoned by the telepathic power of the Rider...