Do you want a Deep Dragon of your own? I sure hope you can hatch one; there's no hope of ever capturing one in the wild. Deep Dragons dwell in unfathomable depths, down past even the bottom of the ocean floor, in trenches that seem to dip into the very center of the Earth.
How do Deep Dragons survive high-pressure subseafloor environments of deep ocean trenches? And if they're so used to those environments, how can they live comfortably on your Dragon Isle? These adaptable creatures have an internal air regulatory system that adjusts their bodies to suit the pressure around them.
Deep Dragon's large round eyes allow them to pick up trace amounts of light, giving them a sort of 'night vision' to safely swim or fly in dark areas. This is especially helpful for Deep Dragons, as they chiefly reside in scarcely lit oceanic trenches. They could probably fly in the vast vacuum of space! ...if they could get up there.
Don't worry about your Epic Deep Dragon's social skills; they get along fine with other dragons! In the wild though, Epic Deep Dragons are isolated from other dragons and animals alike. Few animals can sustain the harsh aquatic terrains of the Epic Deep Dragons, and those who can are terrified of the astronomical albatross.