Don't Wake the Runt. He Is the Dragon King

Aiden was the Silver Dragon King who sealed the world's doom and died for it. Reborn as the weakest runt of the Greystone clan—a tiny white dragon who can barely breathe fire—he hides his power and plays the lazy youngest son. When enemies storm the castle and threaten his family, the 'useless' cub shows them why a dragon king never truly falls.