Separate the stardust from the dirt
He watches the moon sometimes. It's big and silvery and the shadows it casts are beautiful, and he likes to watch the pretty light dance across his pale skin. The moonlight makes him glow.
Sometimes he really needs to shine, in a world tainted by blood and dirt, and he comes out under the moon's light and he glimmers like a diamond in the dirt.
When he's not bathing in the moonlight, he blends in with the greygrey world; he himself is so dirty and foul that he is camouflaged amongst the filth and his broken pieces mingle with the shattered world. But at night he comes alive and he shines the way he was born to.
But then the grey world turns black around him, and the moon is not so bright and the stars all supernova and he is far to broken to shine any more and his light is hidden by layers of dirt and blood and pain.
He gets through it in the end and the world heals itself around him but he bears his scars and is (not really) proud of them (Astoria thinks he should be).
He has a son who shines the way he does. He is a radiant shard of silver in this not so grey world, and no amount of dirt will lessen that.
But sometimes he still goes and stands in the moonlight and it flickers off his scars and he glows, just the way he was born to.