The Dragon Kings had long sensed during Ian's transportation that a 'phase' of their life span limit had been unlocked, and one phase equated to five hundred years. This was precisely the authority Ian unlocked for them with his remaining Star God power after his Ascension stagnated.
Although the Dragon Kings did not fear death, living another lifetime was undeniably a grace and virtue. Ian also proved that as long as one is a Star God, there is a method to resolve the True Dragon's lifespan issue. The infinite potential of Flesh and Blood True Dragons is one matter, but their willingness to continue living is another.
In the eyes of the Dragon Kings, Ian was already synonymous with the Star God; Ian was the Star God, the heir of The Creator—those who troubled Ian would find trouble with Dragon Island!
