Official text extracted from Panzer Dragoon Orta.
Some of the rare sightings of dragons tell of humans who ride atop their backs, despite their innate aggressive nature. A normal human is little equipped to withstand the sheer force involved in dragon combat or flight, so it seems safe to assume that the dragon creates some sort of barrier to protect the rider from impacts and enemy attacks.
From this, it is hypothesized that dragons were originally designed as manned weapons, controlled perhaps by drones. It appears that dragons require the sharing of thought and senses with a rider to realize their full potential as a combat organism.
Why they are incomplete by design remains a mystery, but some speculate that this is a safeguard on an otherwise perfect and all-powerful being. Also, while the rider is in contact with the dragon, the rider’s physical abilities and senses are heightened. Furthermore, even after the direct contact ends, strong residual influence to personality and intelligence have also been reported.
Some old texts tell of riders who felt no fear or compassion while riding dragons. While the details are unknown, it seems clear that once a human comes into contact with these godly creatures and gets a glimpse of their extraordinary world, it is difficult to return to the world of the normal and mundane. For their riders as well, dragons can be the bringers of happiness or despair.