Saix is a Trel, which is basically the lava equivalent of the shaz. There are Trel'lock, Trel'Dolai, and Trel'rae, just like with the shaz, they just thrive in SUPER hot water and magma and will actually freeze up if they get too cold. They eat gemstones which super heat in their bloodstream and turn it radiant colors. All the cracks on his flesh show through to his core, which is the vibrant color of whatever gemstones he ate recently.
Their ears are used to absorb heat, if they're out in the sunlight, they'll fan out their ears to take in all the heat they can, but if they're in the cold, they'll fold their ears down to preserve what warmth they have. Generally Trel live in the caverns beneath the demon capital as this is the most abundant source of magma pools and has a large quantity of hidden gem veins beneath the surface.