The Eternal Kingdom is unlike the other kingdom. They could survive through the passage of time just by relying on their vast and deep foundation. It is also why they dare antagonize everyone without fear of repercussion.
Still, this deep heritage and foundation have limits. Fortunately, Mira is waking up from slumber now. Otherwise, their kingdom will crumble in less than a hundred years.
This is something that neither Vlad nor Darren want to see. The Eternal Kingdom is not only their home but also their master castle and palace. Unfortunately, Vlad and Darren have their lives bound to Mira.
When Mira goes into a deep slumber Vlad and Darren also slowly weaken. In the end, they are also forced to make a deep slumber like Mira.
Therefore, they couldn't pay attention to the Eternal kingdom all the time. They must leave this job to their descendant or the next Vampire King.