Rafadel

Lore:
"...Solar eaters are the dragons, who spend a lot of time in caves, beneath the ground. They don't care much about gold, gems and other treasures, their only desire is a mineral called solarite, or solar ore. This mineral is extremely rare. Millions of years ago, it formed on the world's surface and ore samples absorbed the sunlight, but because of disasters, earth movement, and time they are now hidden underground.
Eaters need this ore in order to live. Solarite is the only thing they can properly feed on. Physical food like meat or seafood only saves their bodies from starving, but only solar ore can save their minds and souls. Their glowing belly indicates their condition, when well-fed with solar energy the eater has a bright, shiny belly, while hungry eaters are much more pale. The hungrier the eater is - the less sane it becomes.

Purely insane (or, as it's a more common belief, soulless) solar eaters don't seek solarite any more. They are afraid of staying in caves and spend all their time in the sunlight. Cloudy weather makes them panic, and long cloudy seasons can even kill them. Insane solar eaters are desperate, the only helpful thing for them is a piece of solar ore, but they only can be saved by friends or families because in their state they can't get solarite by themselves."