The green dragon clan was considered as the police of the empire while the red clan represented the red dragons throughout the universe and gave them a voice against the other three royal clans.
As for the black clan? They were responsible for approving any of the decisions taken by other three clans that could affect the empire as a whole.
In other sense, they were the head of the snake since the current Elder Dragon was from their clan.
The white clan's responsibilities were truly unworthy of the tyranny and authoritative that dragons should own.
Dragons were born to rule, dominate, eat, f*ck, and sleep, just like kings...Not manage the economy and businesses.
"Well, all I can promise is that I will do my best as the captain." Anastasia smiled wryly, "But, don't put your hopes too much. I am not confident in being able to take down Prince Domino and Prince Arentis."