Based on the art created by Omniluci.estumbra (On Instagram/Twitter)

Within his constellated form, which can be perceived by humans, is a blue colored Draco, with horns, ranging in height of eight feet naturally, while in human form it ranges to only 6'0ft. (for his truest evolute form becoming a whopping 12ft.)
Coming with his name sake, he likes to hoard a range of anything he can get his hands on. If its your own or not, he will snatch it to become a piece of treasure in his hoard.
During the day since he's only supposed to be awake during the night with the rest of the stars. Any excess use of his powers during the day can drain hm of energy. Within the form of his human self, his constellations become light moles across his skin.
He only has 3 toes, alike the rest of his Celestial family (Coming from the Black Bloodline, being close to his uncle Sirius Black. Who taught him as much as he possibly could.) (Within his Celestial form, he has a long tail, sharp teeth and horns. Horns he shrinks down in his human form to hide)
When Jealous his blue celeste skin creeps up like blush.